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WPO201000010 Plan - Stormwater Stormwater Management Plan 2009-10-01
CHARLOTTESVILLE- -Th ALBEAIARLE AIRPoRT r Stormwater Management Report CONSTRUCT RUNWAY 3 TEMPORARY OFFSET LOCALIZER/DME AIP PROJECT NO. NON-AIP DELTA PROJECT NO. VA 08107 For The C HARLOTTESVI LLE-ALBEMARLE AIRPORT AUTHORITY vis SUSAN E.WINSLOW LIC.NO.026212 OCTOBER 2009 ° ww ria 4S6'IONAL ci1 441% ,e'*:._,..!%. DELTA AIRPORT ----- CONSULTANTS, INC. 9711 Farrar Court, Suite 100 • Richmond, Virginia 23236 phone: (804) 275-8301 • fax: (804) 275-8371 • www.deltaairport.com STORMWATER MANAGEMENT PLAN CONSTRUCT RUNWAY 3 OFFSET LOCALIZERIDME CHARLOTTESVILLE-ALBEMARLE AIRPORT CHARLOTTESVILLE, VIRGINIA DELTA PROJECT NO. VA 08107 October 2009 TABLE OF CONTENTS Introduction 2 Project Scope 2 Erosion and Sediment Control 3 Stormwater Management Approach 3 Water Quality 4 APPENDICES: APPENDIX 1 Drainage Area Maps APPENDIX 2 Channel Calculations APPENDIX 3 Erosion & Sediment Control Calculations APPENDIX 4 Stormwater ManagementCalculations APPENDIX 5 Water Quality Calculations APPENDIX 6 Project Bid Tabulations APPENDIX 7 Completed County Review Checklist APPENDIX 8 County Applications APPENDIX 9 County Backup Data for Project Site 1 VA 08107 CO23.SWMP STORMWATER MANAGEMENT PLAN DESIGN NARRATIVE CONSTRUCT RUNWAY 3 OFFSET LOCALIZER/DME CHARLOTTESVILLE-ALBEMARLE AIRPORT CHARLOTTESVILLE, VIRGINIA DELTA PROJECT NO. VA 08107 October 2009 Introduction Charlottesville-Albemarle Airport is located within Albemarle County,Virginia approximately seven miles north of the City of Charlottesville. The Airport is bounded on the south and east by State Route 606 and on the west by Route 743 and residential areas. The site of construction is within the borders of the Airport property. The project site is located just outside of the Runway Safety Area(RSA), an area of minimal slope located adjacent to the runway, and between two water protection ordinance stream buffers. The project will not impact either of these stream buffer areas. The existing topography of the project site is steeply sloped grass. Slopes range from as steep as 33% (3:1) to as shallow as 3% (33:1). No critical slopes will be disturbed by this project. All existing slopes greater than 25% (4:1)were constructed under previously approved site plans. All proposed grades will be 25% (4:1) or flatter. Project Scope The project Scope of Work includes the following items: A. Grade platform for Navigational Aids (NAVAIDS) B. Install temporary NAVAIDS. a a a 2 VA 08107 CO23.SWMP a The goal of the project is to install temporary NAVAIDs including both a Localizer (LOC) and Distance Measuring Equipment(DME)at a temporary offset location. The existing LOC is located approximately 300' from the current runway 21 end. As a result,it is within the grading limits of the runway extension project,and must be relocated in order to permit the grading required to construct the 800' Runway extension and associated RSA. This equipment is required to maintain an operational Instrument Landing System(ILS). This system allows aircraft to operate during periods of low visibility. Without it, the Charlottesville-Albemarle Airport (CHO) would not be able to remain open during these conditions. This would result in an interruption of service as well as a safety hazard. CHO is served by only one ground based ILS system. During low visibility conditions, CHO serves as an alternate landing site for many of the Virginia's Airports in the event that conditions enroute deteriorate or worst, an emergency occurs. The temporary NAVAID facilities associated with this project will be installed only for the period required to complete the full Runway extension. Once the extension is complete, new NAVAIDs will be installed at their final location just outside of the RSA on the proposed embankment. LOCs are sophisticated radio antennas. In order for an aircraft to properly receive the LOC radio signal,the LOC must be placed so that it has adequate line of sight to approaching aircraft. Also, it must be placed as close to the runway centerline as possible. As the equipment moves away from the centerline it becomes less precise,until it no longer provides an ILS approach. As a result,an earth platform is required to raise the antenna to the grade along the runway. This platform will be approximately 150' by 75' in size with slopes no greater than 25% (4:1) tying into existing grade. This proposed embankment will require a slight realignment of the airport perimeter road. Erosion and Sediment Control Erosion and sediment control measures will be provided as required by the Virginia Erosion and Sediment Control Handbook(VESCH). Silt Fence,sediment traps,channel linings,and construction entrances are designed to protect the entire limits of disturbance for this project in accordance with VESCH. The majority of the site,including the LOC platform and relocated access road,drains to sediment traps at each outfall. These calculations are provided in Appendix "3" in this report. Stormwater Management Approach An analysis of the pre-developed and developed project site was completed to ensure downstream facilities are protected from increased flow rate and volume. In accordance with the Albemarle County Design Standards Manual dated August 18,2008 and the Virginia Stormwater Management Handbook(VSMH), First Edition,dated 1999,the 2 and 10 year storm occurrences were examined using the rational method. Developed runoff was reduced to pre-developed conditions for the 2 and 10 year storms as required by minimum standard 19. Two biofilters are designed to detain volumes in excess of the pre-developed volumes. By detaining this additional volume, developed runoff is reduced to satisfy the pre-developed runoff conditions. The results of the project site analysis are presented below. 3 VA 08107 CO23.SWMP w Stormwater Management Analysis Summary Qpre Qpost Area 1, 2 Year 0.58 CFS 0.00 CFS Area 1, 10 Year 0.78 CFS 0.56CFS Area 2, 2 Year 1.22 CFS 0.89 CFS Area 2, 10 Year 1.66 CFS 1.65 CFS Because of the reduction of peak flow rates from pre-developed conditions for each project outfall for the 2 and 10 year storm occurrences, downstream channels and facilities are protected from additional volume and peak flow,as is required by minimum standard 19. For this reason,there are no proposed adjustments, improvements, or additional construction of downstream stormwater management facilities. The stormwater management analysis report is enclosed in Appendix "4" of this report. In accordance with FAA regulations and the Albemarle County Design Manual all ditch capacities were designed on the 10-year storm, ditch lining has been designed on the 2-year storm. Channel calculations for this project are located in Appendix "2". 1 Water Quality Water Quality Control has been designed to satisfy the requirements outlined in the Albemarle County Design Standards Manual and VSHM. Based upon guidance in these publications, the applicable area for the removal rate calculations was defined as the contributing area to the outfall points of the project limits. The two proposed sedimentation traps required by the erosion and sediment control plan will be retrofitted to biofilters for water quality upon project completion. Biofilters are designed to treat all proposed impervious area for this project. 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H a a a . n II a C y y N N n n y o I I ar 0 O II O n 0 0 ri, T > O o p N p N N N J N w O N _ *L y, W O J W an ii7 QT T T d T J T J ^ N y y 1 Q , ti a _ l d N y y C y C O O +n ,Fa. In io m - (n Vo u a 3 m o m j o o n 0 0 N D _ W O n 9 E o p 401. O O o 2, J �' n 0 0 o u O 0 E O o n ''a ck D o m O R_ 3 3 3 an 5 5 5 o v 'c p ,I. s, m IIS co O N O O O n W N m .04 vIQ D O N All D 'o d p Oin O J N0 O V , n D ri 0 o D n N A MON O V D < N I-- n N r n N I•' F (D II II II I II II II II II = N T N O F; 5 .t. an n O O OI ii 3 NN > O J O O G N Millw o a J o '(Nn O - o o w x w 01 wi > O (D W V J N J of T T T T T n T T n N T T C T C ? -, O 0 'i N -i N m ip N a N N D W W 3 (D 0 .tai J m m o n n is p m 01 n C E -n N O O O ,T pO J J g_ o ITi co 9 m O o m (n N • 3 3 3 J m > > 3 d m n MS ' w 0 J II J D m o v PI > > N O n m + — v F2 s o o n o 0 0 I- IVU - ' D d J S N 2.n O 0 J OI' d N O ' • 0 m N N - N N n a N C OT 3 \ C 'a1f � n + + ?m 0 m a a 43 W w .- 5) d =++ o N > 0 N N N N O N N d y T 3 O O O O D m .0 un, a n < 0 -r m 0 n n 3 N N 94 "-`1, O co was DITCH CALCULATOR Charlottesville-Albemarle Airport - Charlottesville,Virginia Delta Project No.VA 08107 Date: OCTOBER 12,2009 AREA#1 AREA#2 Storm (Year) 2 10 2 10 Actual Q(cfs) 0.93 1.28 1.83 2.52 VELOCITIES 0...Calculated Flow(Q=vA)(cfs) Q= 0.97 1.32 1.88 2.52 Y YE!"OLI�E� .•- ARE W 1i1-II 4 , Velocity(fps) v= 1.51 1.63 1.31 1.40 t LLoWABLE Hydraulic Radius R= 0.19 0.22 0.29 0.32 VELOCITY OF kk Wetted Perimeter(ft) P= 3.30 3.71 4.95 5.52 2S GFS `" Cross-Sectional Area(sf) A= 0.64 0.81 1.44 1.80 Channel Width(Top)(ft) W= 3.20 3.60 4.80 5.36 Manning Coefficient n= 0.05 0.05 0.05 0.05 Side slope(H:1) S(s)= 4 4 4 4 Flow Depth(ft) D= 0.40 0. 5 6 0.60 7 9 are Longitudinal Slope(ft/ft) S(I)= 0.123 0.023 0.01 0.01 Mk Q(Manning)= 0.97 1.32 1.88 2.52 um (7 / ipik DEPTH OF ID rem DEPTHS CHANNEL To ARE LESS TH*N 6E LU4€D WITt-I TWE C NANNEL WKS E 7.4—Design Concepts intended to be used as a protective ditch lining material to be applied when the design velocity exceeds the allowable velocity for Standard EC-2, Jute Mesh. When the design velocity exceeds the allowable velocity for Standard EC-3, a paved (or riprap) lining is required. The Standard EC-3 (Type C) Soil Stabilization Mat may be used as a protective slope lining for dry cut or fill slopes and wet cut slopes to stabilize the slope on which vegetation is being established. (See VDOT Road and Bridge Standards) 7.4.6.3.1 Design Criteria, Geotextile Linings Standard EC-3 Type A is to be employed where the design velocity in the ditch is within the range of 4 to 7 feet per second (fps). Standard EC-3 Type B is to be employed where the design velocity is within the range of7to10fps. A Manning's n-value of 0.05 should be used with Standard EC-3. Typically, the us- o S -ndard EC-3 T •- A should begin at the point we - - i •w velocity exceed. 4 f•s (velo ity is assumed to .e for ow in an C-2 lined channel) -nd change to EC-3, ype c a e appropna e poen until t e design ve ocity excee•s 0 fps or until the velocity decreases so that the use of a ditch lining can be discontinued. Experience has shown that the installation of this material is particularly critical. The design drawings should stress that the material must be installed in strict accordance with the standard drawings and manufacturer's specifications. 7.4.6.4 Riprap Riprap is defined as a blanket of well-graded stone used to counteract the effects of erosion or scouring on channels, ditches, embankments, jetties, shorelines, and bridge substructure members such as abutments and piers. Riprap is usually described in terms of the size and/or weight of the stone whose volume makes up approximately 50 percent of the total mass. The size of the 50 percent stone is measured in terms of its equivalent mean spherical diameter (MSD) and is referred to as the stone's D50. The weight of the 50 percent stone is referred to by its W50. The Department has six standard riprap classifications whose 50 percent stone size and weights and recommended blanket thickness (T) are tabulated in Appendix 7D-3. Additional information on VDOT standard riprap may be found in the Department's Road and Bridge Specifications. The designer shall specify on the plans the type of Riprap and the dimensions (length, width and depth) for placement. The quantity shall be computed using two (2) tons per cubic yard (148 lbs. per cu. ft.) for plan estimating purposes, unless otherwise specified by the District Administrator. Chapter 7—Ditches 8 Channels VDOT Drainage Manual 7-28 of 53 1992 3.17 �` STD & SPEC3.17 STORMWATER CONVEYANCE CHANNEL • ., „„.1.,. .._,..., ... .. Definition A permanent, designed waterway, shaped, sized, and lined with appropriate vegetation or structural material used to safely convey stormwater runoff within or away from a developing area. "` Purpose To provide for the conveyance of concentrated surface runoff water to a receiving channel or system without damage from erosion. cr - 9t a�ti 3 $2f r-3..77: 4...•�sr3 }t T 2.5 r' :' t. '¢ i ' sW 7.--_,-„,til k ��: ' 4,.,r 3"'a , ,... ��,„0„,:4,,,-. COY r a j t l 4 w`� .moi '` n.,,� om x` ,0' : Mat 3 ., -s,,---",--.... h Y W. • - v moi ,,1 -,-:,;,:f,;;,,,,,,,,,,4 �".:; ". ' s `, �. �x s w� ;`.`a- � 4.'",''.."C.;‘' } " M"` 4T�� r, + . hs{ ♦ ` as ''. �. f"Sa .;.S " .,t�^.-7NilY'"'r�r^F' +A 3"'PS.., ,» ro4S F W" 4i-IS...;!, ;1-,,, ` ,;' *+6. ,' x 13 h'" +mad - .4,-,..'`� ° '-, , - r 5} S - c "/*A... � -tea" "'' g,.. r a ' ,.- ,,w' + x t , P 'r` `,c„ f - : . ,-- :.,,,,,...•,-:„!,,, ,,..;,,::--,,e--:„ . ,:,. ,...:4'.4:47,...-?"/;-:;,,, ,s-,-,-,f,2.....*:,,,-.11;:,--;,f--::Iss,..--=4;:,4,7:::;:::y,,,t7-. , . u,.. r. .a ,n,A." 9J"3�' '' , a. � _s-: C ? }7 * '..°lc`� ..sr m.t' 3 „ ¢. 1 ,'' om'" 4r ;' r .4n' crxis � —• '' ,, gYs <,,,..%-....—,- so+f 7 ,,F,,, ars-" -, ,,gip`'` ° 'a. '• 7 t , d �. ,, . wxo�-``n «.r.� + c a ,i F"a , M'* + ..a" " .y' 4 ww t5 .. ? ... :vm _ glia I" I III - 130 1992 3.17 Conditions Where Practice Applies Generally applicable to man-made channels, including roadside ditches and intermittent natural channels, that are constructed or are modified to accommodate flows generated by land development. The implementation of this control should come only after a channel adequacy analysis for capacity and velocity has been performed as per methods noted in Chapter 5, Engineering Calculations. The measure should be installed and stabilized prior to the introduction of post-development flows. This practice is not generally applicable to continuous flowing natural streams. Major streams need full design considerations and calculations. Provisions for protecting the banks of such streams are described in VEGETATIVE STREAMBANK STABILIZATION,Std.&Spec.3.22 and STRUCTURAL STREAMBANK STABILIZATION, Std. & Spec. 3.23. Planning Considerations The design of a channel cross-section and lining is based primarily upon the volume and velocity of flow expected in the channel. If conditions are appropriate, grass or riprap channels are preferred over concrete. While concrete channels are efficient and easy to .. maintain, they remove runoff so quickly that channel erosion and flooding often result downstream. Grass or riprap channels reduce this problem by more closely duplicating a natural system. Besides the primary design considerations of capacity and velocity, a number of other .,ff important factors should be taken into account when selecting a cross-section and lining. These factors include land availability, compatibility with land use and surrounding environment,safety,maintenance requirements, outlet conditions, and soil erodibility factor. If the riprap design is chosen, filter fabric must be used to act as a separator and stabilizer between the stone and the earth. Cross-section design: Vee-shaped ditches are generally used where the quantity of water to be handled is relatively small, such as roadside ditches. A grass or sod lining will suffice where velocities in the ditch are low. For steeper slopes where high velocities are encountered, a riprap, concrete or bituminous concrete lining may be appropriate. Parabolic channels are often used where the quantity of water to be handled is larger and where space is available for a wide, shallow channel with low velocity flow. Riprap should be used where higher velocities are expected and where some dissipation of energy_ (velocity) is desired. Combinations of grass and riprap are also useful where there is a continuous low flow in the channel. Trapezoidal channels are often used where the quantity of water to be carried is large and conditions require that it be carried at a relatively high velocity. Trapezoidal ditches are generally lined with concrete or riprap. III - 131 1992 Plates 3.17-1 and 3.17-2 illustrate the various types of cross-sections and channel linings. Outlet design: Outlet conditions for all channels must be considered. This is particularly important for the transition from a man-made lining, such as concrete and riprap, to a vegetated or non- vegetated lining. Appropriate measures must be taken to dissipate the energy of the flow • prevent scour of the receiving channel. (See OUTLET PRO I'RCTION, Std. & Spec. 3.18). Capacity All channels shall be designed in a manner which satisfies MS #19 of the Virginia Erosion and Sediment Control Regulations. If channel modifications are necessary, the capacity of the channel must be sufficient to cone the 10- ear fre uen d si n storm 24-hour uration wit out overtopping the banks. If pre-development flooding problems exist, the consequences of flooding are severe, or drainage systems which convey larger storms converge with the channel in question, consideration should be given to increasing the capacity beyond the 10-year frequency storm capacity. Velocity �. Channels should be desi•ned so that the velocity of flow expected from a 2-year fre Bec s • •• iP1I • • -. ' • - .s ermissible veloci or t e ji e of hnm_used: While concrete-lined channels can usually be smaller than grass-lined channels, the increased velocity will produce more erosion and flooding downstream. Chapter 5 contains information on engineering calculations for channel design. The VDOT Drainage Manual .k may be referenced for additional information on channel and culvert design. Grass-lined channels provide good protection against erosion, while they provide an aesthetic setting for conveyance of runoff. However, the velocities that grass linings can handle are much lower than those which can be withstood by riprap or concrete-lined channels. For grass linings, the type of vegetation chosen shall be appropriate for the site conditions: i.e., drainage tolerance, shade tolerance, maintenance requirements, etc. (See PERMANENT SEEDING, Std. & Spec. 3.32 and SODDING, Std. & Spec. 3.33). Where �.. there will be a base flow in grass-lined channels, a stone center, a subsurface drain, or other suitable means to handle the base flow shall be provided. Plate 3.17-2 shows typical cross- sections for stone center channels. Refer to RIPRAP, Std. & Spec. 3.19 to choose the ••• correct stone size and for filter fabric specifications. Permissible velocities for •rass-lined channels are shown in Table 3.17-A. III - 132 1992 "`` 3.17 t,-,--._;:, ..% .1" S ,-•.,,. k.f.-1w? vs-':'._A.4*:r .'*.<:.1 ,u..+ lmf:,..Atr5“', ,.,Ko's :,`1-,14 'IC gra 5 :I4-W h iY �+W.��.rt x,. _,.r;� o.`^nom+_ �,.'z''�F h NW TABLE 3.17-A PERMISSIBLE VELOCITIES FOR GRASS-LINED CHANNELS j CHANNEL LINING PERMISSIBLE SLOPE VELOCITYa Bermudagrass 6 ft./second k„ -;lM Reed canarygrass y! 0 - 5% Tall fescue 5 ft./second Kentucky bluegrass Grass-legume mixture 4 ft./second ' Red fescue Redtop Sericea lespedeza 2.5 ft./second Annual lespedeza `' f Small grains (temporary) Bermudagrass 5 ft./second ,); . • 5 - 10% Reed canarygrass ,.:• Tall fescue 4 ft./second Kentucky bluegrass Grass-legume mixture 3 ft./second Bermudagrass 4 ft./second == Greater than 10% Reed canarygrass Tall fescue 3 ft./second Kentucky bluegrass s a For highly erodible soils, permissible velocities should be decreased by 25%. An erodibility factor (K) greater than 35 would indicate a highly erodible soil. Erodibility factors (K-factors) for many Virginia soils are listed in Chapter 6. =-ti Source: Soil and Water Conservation Engineering, Schwab, et.al. III - 135 APPENDIX"3" EROSION & SEDIMENT CONTROL CALCULATIONS 10/19/2009 10:13 AM TEMPORARY SEDIMENT TRAP CALCULATIONS SEDIMENT TRAP # ST1 Charlottesville-Albemarle Airport Charlottesville, Virginia Delta Project No. VA 07024 DRAINAGE AREA= 0.64 AC E&SC DRAINAGE AREA MAP-AREA#1 TOTAL STORAGE= 0.64 AC x 134 CY/AC= 85.8 CY WET/DRY STORAGE REQ'D = 43 CY (EACH) WIDTH = 15 FT LENGTH = 40 FT LENGTH TO WIDTH RATIO=OK SIDE SLOPES = 2 :1 EMBANKMENT TOP WIDTH = 2.5 FT CHECK PLATE 3.13-1 BOTTOM ELEV = 584.0 ' WET STORAGE ELEV= 585.8 ELEV.AT BASE OF STONE FILTER DRY STORAGE ELEV= 587.0 ELEV.AT TOP OF STONE FILTER TOP ELEV= 588.0 LENGTH OF STONE FILTER = 0.64 AC x 6 FT/AC = 4 ft WET VOLUME PROVIDED = 54.9 CY OK DRY VOLUME PROVIDED = 54.5 CY OK TOTAL VOLUME PROVIDED = 109.4 CY OK J:\PROJECT\2008proj\08107 CHO Offset LOC\Design\08107 Sediment Traps_02 1 /2 10/19/2009 10:13 AM TEMPORARY SEDIMENT TRAP CALCULATIONS SEDIMENT TRAP # ST2 Charlottesville-Albemarle Airport Charlottesville, Virginia Delta Project No. VA 07024 DRAINAGE AREA= 0.98 AC E&SC DRAINAGE AREA MAP-AREA#2 TOTAL STORAGE= 0.98 AC x 134 CY/AC= 131.3 CY WET/ DRY STORAGE REQ'D = 66 CY (EACH) WIDTH = 15 FT LENGTH = 30 FT LENGTH TO WIDTH RATIO=OK SIDE SLOPES = 2 :1 EMBANKMENT TOP WIDTH = 2.5 FT CHECK PLATE 3.13-1 BOTTOM ELEV = 585.0 WET STORAGE ELEV = 587.5 ELEV.AT BASE OF STONE FILTER DRY STORAGE ELEV = 589.0 ELEV.AT TOP OF STONE FILTER TOP ELEV = 590.0 LENGTH OF STONE FILTER = 0.98 AC x 6 FT/AC = 6 ft WET VOLUME PROVIDED = 67.1 CY OK DRY VOLUME PROVIDED = 67.4 CY OK TOTAL VOLUME PROVIDED = 134.5 CY OK J:\PROJECT\2008proj\08107 CHO Offset LOC\Design\08107 Sediment Traps_02 2/2 1992 3.13 STD & SPEC 3.13 TEMPORARY SEDIMENT TRAPco Definition A temporary ponding area formed by constructing an earthen embankment with a stone outlet. S Purpose To detain sediment-laden runoff from small disturbed areas long enough to allow the majority of the sediment to settle out. Conditions Where Practice Applies 1. Below disturbed areas where the total contributing drainage area is less than 3 acres. ,h 1 . . a psis. f .' µ..... '4 ,fin' .- F fast_. , rY t., • NO per - n • I It-,-.A'am l ''..""...71$xw+t 1 � .'x �T`� i ‘-. te ,.k.11-4T!'4',"", r � 41 ow . �.•`r. 'n` "..f jY ate' r "" ' ' "'V �r Yr a,. i .;1. �` a�. J ^`..t'' wM F-:"4,' moi,ar, ^� � 'qy+yam. -- s 1 111 7:.' .`°i:�?n * , 7 1a },mn'y 4.4 , § . mos S 70 III - 1992 3.13 2. Where the sediment trap will be used no longer than 18 months (the maximum useful life is 18 months). 3. The sediment trap may be constructed either independently or in conjunction with a TEMPORARY DIVERSION DIKE (Std. & Spec. 3.09). Planning Considerations Sediment traps should be used only for small drainage areas. If the contributing drainage area is 3 acres or greater, refer to SEDIMENT BASIN (Std. & Spec. 3.14). Sediment traps, along with other perimeter controls intended to trap sediment, shall be constructed as a first step in any land-disturbing activity and shall be made functional before upslope land disturbance takes place. Recent studies have been conducted on the performance of sediment traps (and basins) which were constructed using the design criteria found in previous editions of this handbook. The studies indicate that the control measures only achieved a 46% removal of sediment which flowed into them during storm events which caused measurable outflow. To achieve a more acceptable removal rate (60%), it was necessary to revise the design of these measures in this handbook. The total initial storage volume for both the sediment trap andthe TEMPORARY SEDIMENT BASIN (Std. & Spec. 3.14) has been doubled. There are both a "wet" storage volume and a drawdown or"dry" storage volume which help to enhance sediment fall-out and prevent excessive sediment losses during large storm events which occur during the advanced stages of land disturbance (28). In most cases excavation will be required to attain the necessary storage volume. Also, sediment must be periodically removed from the trap to maintain the required volume. Plans should detail how excavated sediment is to be disposed of, such as by use in fill areas on site or removal to an approved off-site location. As noted previously in this handbook, there are numerous other acceptable ways to design many of the erosion control practices within. This is certainly true in the case of the sediment trap. However, variations in its design should be considered judiciously by plan reviewers to ensure that the minimum storage requirements and structural integrity noted in this specification are maintained. ti. Design Criteria Trap Capacity The sediment trap must have an initial storage volume of 134 cubic yards per acre of draina!- ._ - . half of which shall e m t e orm of a •ermanen ••• • • - • prove•e a stable settling me•ium. s e remaining a s a .e in the form of a drawdown III - 71 max: .,� 1992 �_. --- � ,� __; ..�... - 3.13 or dry storage which will provide extended settling time during less frequent, larger storm events. The volume of the wet storage shall be measured from the low point of the excavated area to the base of the stone outlet structure. The volume of the dry storage shall be measured from the base of the stone outlet to the crest of the stone outlet (overflow . mechanism). Sediment should be removed from the basin when the volume of the wet storage.is reduced by one-half. For a sediment trap, the wet storage volume may be approximated as follows: Vi = 0.85 x A, x D, where, V1 = the wet storage volume in cubic feet Al = the surface area of the flooded area at the base of the stone outlet in square feet D1 = the maximum depth in feet, measured from the low point in the trap to the base of the stone outlet The dry storage volume may be approximated as follows: VZ = Al + A2 x D2 where, V2 = the dry storage volume in cubic feet Al = the surface area of the flooded area at the base of the stone outlet in square feet A2 = the surface area of the flooded area at the crest of the stone outlet (overflow mechanism), in square feet D2 = the depth in feet, measured from the base of the stone outlet to the crest of the stone outlet The designer should seek to provide a storage area which has a 2:1 length to width ratio (measured from point of maximum runoff introduction to out et). III - 72 1992 3.13 Note: Conversion between cubic feet and cubic yards is as follows: number of cubic feet x 0.037 = number of cubic yards Excavation Side slopes of excavated areas should be no steeper than 1:1. The maximum depth of excavation within the wet storage area should be 4 feet to facilitate clean-out and for site safety considerations. Outlet The outlet for the sediment trap shall consist of a stone section of the embankment located at the low point in the basin. A combination of coarse aggregate and riprap shall be used to provide for filtering/detention as well as outlet stability. The smaller stone shall be VDOT#3, #357, or#5 Coarse Aggregate (smaller stone sizes will enhance filter efficiency) and riprap shall be "Class I." Filter cloth which meets the physical requirements noted in Std. & Spec. 3.19, RIPRAP shall be placed at the stone-soil interface to act as a"separator." The minimum len_ h of the outlet shall be 6 fe- times the number of acre c nsm the total area •raiiun: ��� - - .:.__ , :. . ..:.��."' `. ��,� . e crest`.f e stone outlet must b= t least 1.0 foot be iw i r •. e em`ban. ent to ensure t at t.e ow travel over the stone and not the embankment. e out et shall be configured as noted in Plate 3.13-2 Embankment Cross-Section The maximum hei ht of the sediment tra embankment shall be 5 feet as measured from the base o e s one of e ' " iriimum`top widths(W)and outlet heights (Ho) for various embankment heights (H) are shown in Plate 3.13-1. Side slopes of the embankment shall be 2:1 or flatter. 5- Removal _ :.,#.�.. . _:.:� Sediment traps must be removed after the contributing drainage area is stabilized. Plans should show how the site of the sediment trap is to be graded and stabilized after removal. Construction Specifications 1. The area under the embankment shall be cleared, grubbed, and stripped of any vegetation and root mat. 2. Fill material for the embankment shall be free of roots or other woody vegetation, organic material, large stones, and other objectionable material. The embankment should be compacted in 6-inch layers by traversing with construction equipment. III - 73 1992 3.13 MINIMUM TOP WIDTH (TIT) REQUIRED FOR SEDIMENT TRAP EMBANKMENTS ACCORDING TO HEIGHT OF EMBANKMENT (FRET) W .. H HO W 1.5 0.5 2.0 2.0 1.0 2.0 2.5 1.5 2.5 .r 3.0 2.0 2.5 3.5 2.5 3.0 `1, H H 4.0 3.0 3.0 4.5 3.5 4.0 V 5.0 4.0 4.5 I 1=1 I EXCAVATED AREA ' - 11iMI MAX. DEPTH = 4' ORIGINAL GROUND ELEV. =Ar Source: Va. DSWC Plate 3.13-1 artrimemems 3. The earthen embankment shall be seeded with temporary or permanent vegetation (see Std. & Spec.'s 3.31 and 3.32) immediately after installation. 4. Construction operations shall be carried out in such a manner that erosion and water pollution are minimized. 5. The structure shall be removed and the area stabilized when the upslope drainage area has been stabilized. 6. All cut and fill slopes shall be 2:1 or flatter (except for excavated, wet storage area which may be at a maximum 1:1 grade). III - 74 .. 1992 3.13 TEMPORARY SEDIMENT TRAP 1' VARIABLE +r. ORIGINAL VARIABLE* GROUND ELEV. 4� iii�d 'rw ;s r:ir•Oftlt�� � 1.0dq l liar* 67 CU. YD./ACRE �� a� r ar N i•?� t. ilMIliwitif ..- VARIABLE* 67 CU. YD./ACRE irr 4 MAX. (EXCAVATED) 'Fir FILTER CLOTH ORIGINAL GROUND ELEV. mito ** *SEE PLATE 3.13-1 COARSE AGGREGATE CLASS I RIPRAP .r CROSS SECTION OF OUTLET CLASS I RIPRAP _ LENGTH (IN FEET) = 4`_ (IINXAC.)AINAGE AREA sow _ � DIVERSION meq\+ �`'�- - { A DIKE <7.," \- \ s ;a'.41r s''' ue \�_ \ MO :c-''. •-••._____.. .__ _/_. .Q z/ • -.--- ,-___- -,-___- ) fc 1 ) COARSE AGGREGATE / / � �� .r �/� EXCAVATED /FILTER CLOTH '�_/ —'� AREA / -�� MS i * COARSE AGGREGATE SHALL BE VDOT #3, #357 OR #5 OMOUTLET (PERSPECTIVE VIEW) a Source: Va. DSWC Plate 3.13-2 a III - 76 a Project No. %.4110 vp w ,.. __ Date 10/Z3 /2.o69 By 3P8 CHANNEL OQTLE.T PRoTEcTioN ? SOLVE FOR THE OPTLET PRoTEcT IoM 10 M ENS IoN 5 FDA THE' PRO CHANNrL IMO TVSEDIMENTTRAP / (3 IOFILTERS, II 1 I 1 1 I II I 1 i , 1 IVS I RAS c'ANNEL (E -z10EbI f. 4:1 EO'8076,010.101104`, 4L_ 1 -1 1 . ;JAI! Ii ' --- � I j I ' • A FIND I� �tiMUM, oAPt.IT_'L T , CHgNNEL� ,Q'tvt,�c moo DIMIEN510NS r ►P- �� — I— I 46. 5OWil ON : . 1 i c P4\01/4X = (I'DEPTH) = I'. 113 .FS (SEE DITGI CA[t.OLATOR SHEET;) • , : p2 -INt U VALENT AREA A O 1FLow FogQkwc , , p 4' -Pc - � %' 0C 2 V l -, 1 ' aQ i + �_ y IAEA zi 4.0 S F CO 1% DEPTH ; , W Z j Ov FMD PIP; 'FOR 4,0 5Fi ; I /10 opo Itig 1• IZ $F ' ; , -i--- ; ____ _ „)/ 1 .l_ SEE R •R,AtPSHEET 7=oR-CALCVSATioNS - 1-, f , OW, WL, $`,; 14_ WI . 1 , ; ; � - -- S� d (:> ` ) A i Zo sY : - Ij 1 , i i— . ! ' , , +rr 1 atiw i DITCH CALCULATOR Charlottesville-Albemarle Airport Charlottesville,Virginia Delta Project No.VA 08107 Date:OCTOBER 12,2009 "-. AREA#1 AREA#2 Storm (Year) 2 10 2 10 Actual Q(cfs) 0.93 1.28 1.83 2.52 Calculated Flow(Q=vA)(cfs) 0= 11.13 11.13 7.34 7.34 Velocity(fps) v= 2.78 2.78 1.83 1.83 Hydraulic Radius R= 0.49 0.49 0.49 0.49 $" Wetted Perimeter(ft) P= 8.25 8.25 8.25 8.25 Cross-Sectional Area(sf) A= 4.00 4.00 4.00 4.00 Channel Width(Top)(ft) W= 8.00 8.00 8.00 8.00 Manning Coefficient n= 0.05 0.05 0.05 0.05 Side slope(H:1) S(s)= 4 4 4 4 Flow Depth(ft) D= 1.00 1.00 12 1.00 1.00 12 Longitudinal Slope(ft/ft) S(I)= 0.023 0.023 0.01 0.01 Q(Manning)= 11.13 11.13 7.34 7.34 1992 CNAcNNEL OUT FALLS 3.18 ASSUME M11•11K M TAILWATER DOE To TME CREST aF THE SED TRAP > 1' QEt.oW c.HANNEL EXIT. ft 4aa. `azis d2-id! 0Sp I-77qq n Og '6 . F.-Mme_-_E.. da-E _ - 4D �.. ` ,`.MCC -:��� _� -..'"a -_ - 'i '-;SST „� , r.���-�r_� _ � ••- •m� JMENEME -___. -�--. .-,---_-__;1....— _..*�1S z?-c'l- s _ 9 4= F M o - -.-- 1111 cx)- — s� 13 .E• E!€ •�.m .. ._ V - G 7�► o ' Z O 7\hII■Il■■■■- ME ._t-4-,-: 011.11111110.11.011.11111110.11. - 2 dJo , ' - , t L 101\■\■�M■■■■ ii■ Oct, • ___. v ■NGA . ' o _I ' 1 1 ��\\11►11111■11npvn2■ IL o = _ = ez •� - 1 o w dr ai40 r _f_ J _ _ ,�F-- ., = _ inyp :� .� � mW 44 Lj z ..- c,_=_-- msE --zot.mr-.,--_ ---.,..:-_-..._f.-.ET= ------E-- 1,k6. Zdm cu Q -Vialg&INXI e‘ > � I --'_ ..07.,.. ..--''...".- 0 11=1 Mgr \ 1. '� a - ...,- . _ .. . . 6' .......8.� • 't i\W•••7. iii.N {� ea) LEL-1 1-12-jN o `n_ sp �� �� ��a�a .�/� V �i \I\\A EEI♦tEE� N Li. ■■■■■o■■■■■ uILI■■■ ■■ate■■ v o 11 +e ■■■■■II■■■■■■6'S\M■■■■■N®■■p 1i1 z o i Cl.' ■■■■■■■■■■•inhim■■i►i■■■■■■■■■■■ ■■ __ ril 2 -) ■"uu■n ■Oa■■n■lorimmnallala Ma - '0 ‹C VI m2; i V I iii im■_■■n1■mn1111MUMMIIMMEMI Ma -- • _ - z z 99• j f l HhI I `■■!i r l Aiili 0 0 3r' ►, tilti ii 2 2 I F ■IBiiiiuuiiiiii■mmusi_e� 0 o N��� ► . 2i ' INIp1►111l�II mluJl �, _ b - ; m �� n����nin z_ ■ ES Emmons'J¢ ch o , I ti l II '- MooG pF- +4 +�Eaiv 1 CD M cnz oao� o .�� M /1 it -o AillO / , ....t.. .. 0 to _ k--'03.-->) % 410 Source: USDA-SCS Plate 3.18-3 III - 164 APPENDIX"4" STORMWATER MANAGEMENT CALCULATIONS Table of Contents i Table of Contents STORM WATER MANAC-SENT ANALYSIS CHO 08107 AREA 1 ********************** MASTER SUMMARY ********************** Watershed Mod. Rational Grand Summary 1.01 Master Network Summary 1.02 ********************** TC CALCULATIONS ********************* Y AREA 1 PRE Tc Calcs 2.01 AREA 1 POST 011 Tc Calcs 2.02 *********************** POND VOLUMES *********************** 4 BIOFILTER 1 Vol: Elev-Area 3.01 ******************** OUTLET STRUCTURES ********************* Outlet 1 Outlet Input Data 4.01 ****************** RATIONAL METHOD CALCS ******************* oo AREA 1 PRE wr C and Area 5.01 AREA 1 POST C and Area 5.02 Nr AREA 1 Dev 2 Rational Predev. Peak Q 5.03 ifr air S/N: 07YXYWJN4T12 Bentley Systems, Inc. PondPack (10.00.016.00) 4:36 PM 10/22/2009 r Table of Contents ii 4.. Mod. Rational Graph 5.04 Mod. Rational Storm Calcs 5.05 AREA 1 Dev 10 .0 Rational Predev. Peak Q 5.06 Mod. Rational Graph 5.07 Mod. Rational Storm Calcs 5.08 AGM ,1111 .00 .01 .00 a a. yr AK 41110 S/N: 07YXYWJN4T12 Bentley Systems, Inc. PondPack (10.00.016.00) 4:36 PM 10/22/2009 Type. . . . Mod. Rational Grand Summary Page 1.01 Name. . . . Watershed File. . . . J:\PROJECT\2008proj\08107 CHO Offset LOC\Design\08107 Area l.ppw 00 wr ************************************************************************ ************************************************************************ * * * * ..r * MODIFIED RATIONAL METHOD * ---- Grand Summary For All Storm Frequencies ---- * ************************************************************************ ************************************************************************ ■r. Q = CiA * Units Conversion; Where Conversion = 43560 / (12 * 3600) Area = .750 acres Tc = .2367 hrs VOLUMES Freq. Adjusted Duration I Qpeak Allowable Inflow Storage ,, years 'C' hrs in/hr cfs cfs ac-ft ac-ft 2 .356 .4000 2.6834 .72 .58 .024 .009 10 .356 .4500 3.5338 .95 .78 .035 .013 100 .356 .5000 5.0892 1.37 1.15 .057 .022 J) STORAGE VOLUME RE.Qt REp To R5DucE PEAK FLOW RATE PRE-DEVELoPED DEvEp PEAK RaJ RASE Fok DEeLOPEb PEPK FLo) RA1E 1U TWE PEAK►=low RATE CoINZT DNS INTO OF ARE-DEVELOPED ammo i tk iS StN. HYDROLIC. VOLUME FOR. DEvEL Ec (ON'D1TioNS. S/N: 07YXYWJN4T12 Bentley Systems, Inc. PondPack (10.00.016.00) 4:36 PM 10/22/2009 r ANL Type. . . . Master Network Summary Page 1.02 Name. . . . Watershed File. . . . J:\PROJECT\2008proj\08107 CHO Offset LOC\Design\08107 Area l.ppw a.. mw MASTER DESIGN STORM SUMMARY Default Network Design Storm File, ID Albemarle County m. AM i = b / HT + d)**e) Where: i = rainfall intensity (in/hr) T = rainfall duration (min) MI e, b, d = rainfall equation coefficients mm Return Event Rainfall Type e coeff b coeff d coeff 2 e, b, d Coeff. 1.0000 106.0200 15.5100 10 e, b, d Coeff. 1.0000 161.6000 18.7300 v+ 100 e, b, d Coeff. 1.0000 265.2000 22.1100 r MASTER NETWORK SUMMARY Modified Rational Method Network (*Node=Outfall; +Node=Diversion;) mm (Trun= HYG Truncation: Blank=None; L=Left; R=Rt; LR=Left&Rt) ■r Max Return HYG Vol Qpeak Qpeak Max WSEL Pond Storage Node ID Type Event ac-ft Trun hrs cfs ft ac-ft mm AREA 1 AREA 2 .024 .2367 .72 3 AREA 1 AREA 10 .035 .2367 •95 PEAK FLA ) RATE AREA 1 AREA 100 .057 .2367 1.37 minik OF DEVELOPED ,SITE BIOFILTER 1 IN POND 2 .024 .2367 .72 BIOFILTER 1 IN POND 10 .035 .2367 .95 *� r� TWE RQ. BIOFILTER 1 IN POND 100 .057 .2367 1.37 �V c mm Air ""' S/N: 07YXYWJN4T12 Bentley Systems, Inc. PondPack (10.00.016.00) 4:36 PM 10/22/2009 Aa 0.0k Type. . . . Master Network Summary Page 1.03 Name. . . . Watershed File. . . . J:\PROJECT\2008proj\08107 CHO Offset LOC\Design\08107 Area 1.ppw MASTER NETWORK SUMMARY w Modified Rational Method Network (*Node=Outfall; +Node=Diversion; ) .r. (Trun= HYG Truncation: Blank=None; L=Left; R=Rt; LR=Left&Rt) .1r Max Return HYG Vol Qpeak Qpeak Max WSEL Pond Storage Node ID Type Event ac-ft Trun hrs cfs ft ac-ft BIOFILTER 1 OUT POND 2 .000 .0237 .00 586.97 .024 BIOFILTER 1 OUT POND 10 .011 .5444 .56 587.13 .029 BIOFILTER 1 OUT POND 100 .032 .5207 1.30 587.23 .032 ... *OUT 10 JCT 2 .000 .0237 .00 *OUT 10 JCT 10 .011 .5444 .56 *OUT 10 JCT 100 .032 .5207 1.3 PEAK FLOW RATE OUT OF THE PROPOSED BASIN. Qi ( os-c) = D.co CFS ctZ (FRE)= 0.5$ CFS Q to (POST) = 6.S() CFS am (9RE) =- 0.1$ CFS a ` S/N: 07YXYWJN4T12 Bentley Systems, Inc. PondPack (10.00.016.00) 4:36 PM 10/22/2009 00 Type. . . . Tc Calcs Page 2.01 Name. . . . AREA 1 Tag: PRE +� File. . . . J:\PROJECT\2008proj\08107 CHO Offset LOC\Design\08107 Area l.ppw . PRE—DEvELD D TIME OF CONCENTRATION CALCULATOR SEE PRE-Dem.0PED DR M (4E ARES MAKE/Weir) FOR ►=L.oW Patel. Segment #1: Tc: TR-55 Sheet Mannings n .2400 Hydraulic Length 100.00 ft 2yr, 24hr P 3.7000 in Slope .040000 ft/ft Avg.Velocity .17 ft/sec Segment #1 Time: .1676 hrs wr Segment #2: Tc: TR-55 Channel Flow Area 2.0000 sq.ft Wetted Perimeter 8.12 ft Hydraulic Radius .25 ft Slope .070000 ft/ft Mannings n .0300 40. Hydraulic Length 200.00 ft Avg.Velocity 5.16 ft/sec .. Segment #2 Time: .0108 hrs Total Tc: .1784 hrs .s 1 ARO w "r" S/N: 07YXYWJN4T12 Bentley Systems, Inc. PondPack (10.00.016.00) 4:36 PM 10/22/2009 00 Type. . . . Tc Calcs Page 2.02 Name. . . . AREA 1 Tag: POST File. . . . J:\PROJECT\2008proj\08107 CHO Offset LOC\Design\08107 Area l.ppw POST DaEIOPENIENT TIME OF CONCENTRATION CALCULATOR SEE. F43ST DEALOPED DRAINAGE AREA MAP(Ety Err 3) FbQ. Raz PAIN WI Segment #1: Tc: TR-55 Sheet Mannings n .2400 AWNHydraulic Length 65.00 ft 2yr, 24hr P 3.7000 in Slope .020000 ft/ft Avg.Velocity .12 ft/sec Segment #1 Time: .1567 hrs Segment #2: Tc: TR-55 Sheet Mannings n .2400 Hydraulic Length 85.00 ft 2yr, 24hr P 3.7000 in Slope .250000 ft/ft Avg.Velocity .33 ft/sec Segment #2 Time: .0707 hrs Segment #3: Tc: Length & Vel. Hydraulic Length 50.00 ft Avg.Velocity 1.49 ft/sec Segment #3 Time: .0093 hrs w Total Tc: .2367 hrs S/N: 07YXYWJN4T12 Bentley Systems, Inc. PondPack (10.00.016.00) 4:36 PM 10/22/2009 Type. . . . Vol: Elev-Area Page 3.01 Name. . . . BIOFILTER 1 File. . . . J:\PROJECT\2008proj\08107 CHO Offset LOC\Design\08107 Area l.ppw Elevation Planimeter Area Al+A2+sqr(Al*A2) Volume Volume Sum (ft) (sq.in) (acres) (acres) (ac-ft) (ac-ft) mop 586.00 .0200 .0000 .000 .000 587.00 .0300 .0745 .025 .025 588.00 .0400 .1046 .035 .060 NOTE: THESE CALCULATIONS Do NOT CAA 510ER i NFILTRPTION THROUC•H THE 1310F«TEi.. a WNW WW WW WW 4W AW " S/N: 07YXYWJN4T12 Bentley Systems, Inc. PondPack (10.00.016.00) 4:36 PM 10/22/2009 Type. . . . Outlet Input Data Page 4.01 Name. . . . Outlet 1 File. . . . J:\PROJECT\2008proj\08107 CHO Offset LOC\Design\08107 Area l.ppw REQUESTED POND WS ELEVATIONS: Min. Elev.= 586.00 ft Increment = .10 ft Max. Elev.= 588.00 ft 11111 ********************************************** OUTLET CONNECTIVITY ********************************************** ---> Forward Flow Only (UpStream to DnStream) <--- Reverse Flow Only (DnStream to UpStream) <---> Forward and Reverse Both Allowed Structure No. Outfall El, ft E2, ft Weir-Rectangular WO ---> TW 587.000 588.000 TW SETUP, DS Channel Ad 60 14 Ott OS Oo i` S/N: 07YXYWJN4T12 Bentley Systems, Inc. PondPack (10.00.016.00) 4:36 PM 10/22/2009 at Type. . . . Outlet Input Data Page 4.02 Name. . . . Outlet 1 File. . . . J:\PROJECT\2008proj\08107 CHO Offset LOC\Design\08107 Area l.ppw OUTLET STRUCTURE INPUT DATA Structure ID = WO Structure Type = Weir-Rectangular rw # of Openings = 1 Crest Elev. = 587.00 ft Weir Length = 4.00 ft Weir Coeff. = 3.000000 Aft Weir TW effects (Use adjustment equation) Structure ID = TW Structure Type = TW SETUP, DS Channel wo FREE OUTFALL CONDITIONS SPECIFIED CONVERGENCE TOLERANCES. . . WISM Maximum Iterations= 40 Min. TW tolerance = .01 ft Max. TW tolerance = .01 ft .r Min. HW tolerance = .01 ft Max. HW tolerance = .01 ft Min. Q tolerance = .00 cfs Max. Q tolerance = .00 cfs rr a a Aro .w Ar S/N: 07YXYWJN4T12 Bentley Systems, Inc. PondPack (10.00.016.00) 4:36 PM 10/22/2009 a Type. . . . C and Area Page 5.01 Name. . . . AREA 1 Tag: PRE File. . . . J:\PROJECT\2008proj\08107 CHO Offset LOC\Design\08107 Area 1.ppw RATIONAL C COEFFICIENT DATA PRE- DEVELoPED ANN set PRE-osvELCPEo DRA►NA`E AREA MAP (ExHIBIT z) 5-DR CAOM OWER rr Area C x Area Soil/Surface Description C acres acres Grass .3000 .320 .096 Impervious .9000 .050 .045 WEIGHTED C & TOTAL AREA ---> .3811 .370 .141 rr arr ++r A* arr 8.r a .111 S/N: 07YXYWJN4T12 Bentley Systems, Inc. PondPack (10.00.016.00) 4:36 PM 10/22/2009 a Type. . . . C and Area Page 5.02 Name. . . . AREA 1 Tag: POST File. . . . J:\PROJECT\2008proj\08107 CHO Offset LOC\Design\08107 Area l.ppw RATIONAL C COEFFICIENT DATA POST OEv Et.ottMeNT SEE POT DE'at oPED 6,RA1NAtrE AREA MAP(EXrUBiT 3) FoR Gr;NNO[NEP,. a Area C x Area Soil/Surface Description C acres acres Grass .3000 .680 .204 Impervious .9000 .070 .063 WEIGHTED C & TOTAL AREA ---> .3560 .750 .267 as as ar ■aa aaa ++r a.. a as air as �. S/N: 07YXYWJN4T12 Bentley Systems, Inc. PondPack (10.00.016.00) 4:36 PM 10/22/2009 - Type. . . . C and Area Page 5.02 Name. . . . AREA 1 Tag: POST AI"' File. . . . J:\PROJECT\2008proj\08107 CHO Offset LOC\Design\08107 Area l.ppw 0 Type. . . . Rational Predev. Peak Q Page 5.03 Name. . . . AREA 1 Event: 2 yr File. . . . J:\PROJECT\2008proj\08107 CHO Offset LOC\Design\08107 AREA 1.PPW Storm. . . e, b, d Tag: Dev 2 SUMMARY OF RATIONAL METHOD PEAK DISCHARGES dm PREDEVELOPED CONDITIONS --- Q = CiA * Units Conversion; Where Conversion = 43560 / (12 * 3600) Tag Freq File IDF Curve 00 Dev 2 2 e = 1.0000 b = 106.0200 d = 15.5100 Tc = .1784 hrs Tag Freq C C adj C I Area I Peak Q (years) factor I final in/hr acres I cfs Dev 2 2 .381 1.000 I .381 4.0445 .370 I 58 Ar. (///) w PEAK FLG ) RATE OF PRE-DEvEltP¢D AMP 100 41111 0 S/N: 07YXYWJN4T12 Bentley Systems, Inc. PondPack (10.00.016.00) 4:36 PM 10/22/2009 ar 01u Type. . . . C and Area Page 5.02 Name. . . . AREA 1 Tag: POST File. . . . J:\PROJECT\2008proj\08107 CHO Offset LOC\Design\08107 Area l.ppw m. U Type. . . . Mod. Rational Graph Page 5.04 Name. . . . AREA 1 Tag: Dev 2 Event: 2 yr File. . . . J:\PROJECT\2008proj\08107 CHO Offset LOC\Design\08107 AREA 1.PPW Storm. . . e, b, d Tag: Dev 2 MODIFIED RATIONAL METHOD 40 ---- Graphical Summary for Maximum Required Storage ---- Method I mmQ = CiA * Units Conversion; Where Conversion = 43560 / (12 * 3600) ****************************************************************��*pp***** fs rlr 410 * RETURN FREQUENCY: 2 yr I Allowable Outflow: .58 ct * * 'C' Adjustment: 1.000 1 Required Storage: .0099 ac-ft * * * Peak Inflow: .72 cfs „r, * .HYG File: Dev 2 ********************************************************************** s QI Td = .4000 hrs Return Freq: 2 yr / Approx. Duration for Max. Storage / C adj .factor:1.000 ,.r Tc= .2367 hrs I = 3.5679 in/hr Area = .750 acres . Q = .96 cfs Weighted C = .356 • 1 . Adjusted C = .356 . Required Storage Td= .4000 hrs am • 1 1 I = 2.6834 in/hr xxxxxxxixxxxxxxxxxx Q = .72 cfs P°ST IN +n o Q = .58 cfs PRE . x o x (Allow.Outflow) . x o . x o NOT TO SCALE x . x o o x .4483 hrs T err mop S/N: 07YXYWJN4T12 Bentley Systems, Inc. PondPack (10.00.016.00) 4:36 PM 10/22/2009 Type. . . . Mod. Rational Storm Calcs Page 5.05 Name. . . . AREA 1 Tag: Dev 2 Event: 2 yr File. . . . J:\PROJECT\2008proj\08107 CHO Offset LOC\Design\08107 Area l.ppw a" Storm. . . e, b, d Tag: Dev 2 rr MODIFIED RATIONAL METHOD ---- Summary for Single Storm Frequency ---- 41111 Q = CiA * Units Conversion; Where Conversion = 43560 / (12 * 3600) RETURN FREQUENCY: 2 yr 'C' Adjustment = 1.000Allowable Q = .58 cfs T A E MO Hydrograph Storm Duration, Td = .4000 hrs Tc = .2367 hrs Hydrograph File: Dev 2 air VOLUMES Wtd. Adjusted Duration Intens. Area Qpeak Inflow Storage 'C' 'C' hrs in/hr acres cfs ac-ft ac-ft mo .356 .356 .2367 3.5679 .750 .96 .019 .008 .356 .356 .2500 3.4749 .750 .94 .019 .008 .356 .356 .3333 2.9856 .750 .80 .022 .009 ************************************************************ Storage Maximum .356 .356 .4000 2.6834 .750 .72 1 .024 .009 ************************************************** ************************ MION .356 .356 .5000 2.3296 .750 .63 1 .026 .008 .356 .356 .6667 1.9099 .750 .51 1 Qpeak < Qallow Po5TIN am aw me ars MN ®r S/N: 07YXYWJN4T12 Bentley Systems, Inc. PondPack (10.00.016.00) 4:36 PM 10/22/2009 w■ Type. . . . Rational Predev. Peak Q Page 5.06 Name. . . . AREA 1 Event: 10 yr File. . . . J:\PROJECT\2008proj\08107 CHO Offset LOC\Design\08107 Area l.ppw wo` Storm. . . e, b, d Tag: Dev 10 SUMMARY OF RATIONAL METHOD PEAK DISCHARGES PREDEVELOPED CONDITIONS Q = CiA * Units Conversion; Where Conversion = 43560 / (12 * 3600) MO Tag Freq File IDF Curve Dev 10 10 e = 1.0000 b = 161.6000 d = 18.7300 Tc = .1784 hrs Tag Freq C C adj I C I Area I Peak Q (years) factor I final in/hr acres I cfs I I Dev 10 10 .381 1.000 I .381 5.4904 .370 I .78 P VAK Fut4 RATE 0X PRE-avvL 'E D CMbiTioNS. OW MO MO OW MO VW S/N: 07YXYWJN4T12 Bentley Systems, Inc. PondPack (10.00.016.00) 4:36 PM 10/22/2009 Type. . . . Rational Predev. Peak Q Page 5.06 Name. . . . AREA 1 Event: 10 yr File. . . . J:\PROJECT\2008proj\08107 CHO Offset LOC\Design\08107 Area l.ppw &'° Storm. . . e, b, d Tag: Dev 10 0 dip Type. . . . Mod. Rational Graph Page 5.07 Name. . . . AREA 1 Tag: Dev 10 Event: 10 yr File. . . . J:\PROJECT\2008proj\08107 CHO Offset LOC\Design\08107 AREA 1.PPW Storm. . . e, b, d Tag: Dev 10 MODIFIED RATIONAL METHOD ---- Graphical Summary for Maximum Required Storage ---- Method I Q = CiA * Units Conversion; Where Conversion = 43560 / (12 * 3600) **************************************************************t*�******* * RETURN FREQUENCY: 10 yr I Allowable Outflow: .78 cfs PRE * * 'C' Adjustment: 1.000 Ie'�'t'quii'ea 5turage: .013 ac-ft * * * Peak Inflow: .95 cfs * * .HYG File: Dev 10mw * ********************************************************************** Q I Td = .4500 hrs I Return Freq: 10 yr / Approx. Duration for Max. Storage / C adj .factor:1.000 Tc= .2367 hrs I = 4.9067 in/hr Area = .750 acres . Q = 1.32 cfs Weighted C = .356 es • I • Adjusted C = .356 • I • • I • Required Storage .013 ac_}L Td= .4500 hrs or • I • I I = 3.5338 in/hr xxxxxxxlxxxxxxxxxxx Q = .95 cfs poST �N • X x OW o Q = .78 cfs PPE • x o x (Allow.Outrrow) . x o . x o NOT TO SCALE x . x 0 o x .4925 hrs T ars a.. S/N: 07YXYWJN4T12 Bentley Systems, Inc. PondPack (10.00.016.00) 4:36 PM 10/22/2009 .r, Type. . . . Mod. Rational Storm Calcs Page 5.08 Name. . . . AREA 1 Tag: Dev 10 Event: 10 yr File. . . . J:\PROJECT\2008proj\08107 CHO Offset LOC\Design\08107 Area l.ppw MO MO MODIFIED RATIONAL METHOD ---- Summary for Single Storm Frequency ---- "1O Q = CiA * Units Conversion; Where Conversion = 43560 / (12 * 3600) RETURN FREQUENCY: 10 yr 'C' Adjustment = 1.000Allowable Q = .78 cfs PRE .r Hydrograph Storm Duration, Td = .4500 hrs Tc = .2367 hrs Hydrograph File: Dev 10 mar VOLUMES Wtd. Adjusted Duration Intens. Area Qpeak Inflow Storage 'C' 'C' hrs in/hr acres cfs ac-ft ac-ft mi` .356 .356 .2367 4.9067 .750 1.32 .026 .011 .356 .356 .2500 4.7910 .750 1.29 .027 .011 .356 .356 .3333 4.1725 .750 1.12 .031 .013 MO ************************************************************ Storage Maximum .356 .356 .4500 3.5338 .750 .95 1 .035 .013 ************************************************** *****************OM • .356 .356 .5000 3.3162 .750 .89 I .037 .013 .356 .356 .6667 2.7516 .750 .74 1 Qpeak < Qallow .. 05 1. .r MB *r MO MO OM MIS rr S/N: 07YXYWJN4T12 Bentley Systems, Inc. PondPack (10.00.016.00) 4:36 PM 10/22/2009 NN Table of Contents i NM Table of Contents S7tRMwATE MANAGEMENT ANALYSIS CI-t) x9101 AREis ********************** MASTER SUMMARY ********************** an Watershed Mod. Rational Grand Summary 1.01 Master Network Summary 1.02 ********************** TC CALCULATIONS ********************* AREA 2 PRE Tc Calcs 2.01 AREA 2 POST Tc Calcs 2.02 *********************** POND VOLUMES *********************** BIOFILTER 2 Vol: Elev-Area 3.01 10 ******************** OUTLET STRUCTURES ********************* Outlet 1 Outlet Input Data 4.01 ire ****************** RATIONAL METHOD CALCS ******************* AREA 2 PRE or C and Area 5.01 AREA 2 POST C and Area 5.02 ow AREA 2 Dev 2 Rational Predev. Peak Q 5.03 IN ON S/N: 07YXYWJN4T12 Bentley Systems, Inc. PondPack (10.00.016.00) 4:34 PM 10/22/2009 Ito 4011 Table of Contents ii mo mom Mod. Rational Graph 5.04 Mod. Rational Storm Calcs 5.05 AREA 2 Dev 10 Rational Predev. Peak Q 5.06 Mod. Rational Graph 5.07 Mod. Rational Storm Calcs 5.08 WO .r MW MO MO MO MA VIA a a ' S/N: 07YXYWJN4T12 Bentley Systems, Inc. PondPack (10.00.016.00) 4:34 PM 10/22/2009 ."" Type. . . . Mod. Rational Grand Summary Page 1.01 Name. . . . Watershed File. . . . J:\PROJECT\2008proj\08107 CHO Offset LOC\Design\08107 Area 2.ppw am am ************************************************************************ ************************************************************************ * * * * MN * MODIFIED RATIONAL METHOD * * ---- Grand Summary For All Storm Frequencies ---- * * * * * .01 ************************************************************************ ************************************************************************ Q = CiA * Units Conversion; Where Conversion = 43560 / (12 * 3600) ,i,. Area = 1.400 acres Tc = .2766 hrs VOLUMES Freq. Adjusted Duration I Qpeak Allowable Inflow Storage em years 'C' hrs in/hr cfs cfs ac-ft ac-ft 2 .364 .3667 2.8264 1.45 1.22 .044 .012 10 .364 .4167 3.6954 1.90 1.66 .065 .018 4,.r 100 .364 .4667 5.2924 2.72 2.44 .105 .030 4°.'. .. "............ .....) If VI p Eq'( FLOW RITE PRE-DEVE IQPED Sit RAGE V LOM E FOR DEVEI�p�E1� PEAK f-tAWRA� I�EQUIREt� 'I'D REDuC.E CmDm ot.15 INTO D LOPED PEAK F-1.04)RATE 'Tl-IE 61oFIL1EfZ 0,1)61NTO E BEAK FI,DW RATE NYDr"".""....) op PRE-DEvEtoP U (Lt 1 GNS, zotoct►L \OLUKIE FOR DEVELOPED CoNDITIoNS, QM MON O s S/N: 07YXYWJN4T12 Bentley Systems, Inc. PondPack (10.00.016.00) 4:34 PM 10/22/2009 "' Type. . . . Master Network Summary Page 1.02 Name. . . . Watershed File. . . . J:\PROJECT\2008proj\08107 CHO Offset LOC\Design\08107 Area 2.ppw AW •r MASTER DESIGN STORM SUMMARY Default Network Design Storm File, ID Albemarle County om i = b / ( (T + d)**e) Where: i = rainfall intensity (in/hr) _. T = rainfall duration (min) e, b, d = rainfall equation coefficients mm Return Event Rainfall Type e coeff b coeff d coeff 2 e, b, d Coeff. 1.0000 106.0200 15.5100 9.. 10 e, b, d Coeff. 1.0000 161.6000 18.7300 100 e, b, d Coeff. 1.0000 265.2000 22.1100 mm MASTER NETWORK SUMMARY Modified Rational Method Network ■r (*Node=Outfall; +Node=Diversion;) (Trun= HYG Truncation: Blank=None; L=Left; R=Rt; LR=Left&Rt) mm Max Return HYG Vol Qpeak Qpeak Max WSEL Pond Storage Node ID Type Event ac-ft Trun hrs cfs ft ac-ft AREA 2 AREA 2 .044 .2766 1.45 AREA 2 AREA 10 .065 .2766 1.90 PEAK RN) RATE AREA 2 AREA 100 .105 .2766 2.72 oF Q�1/EIOP�.D `'� V J BIOFILTER 2 IN POND 2 .044 .2766 1.45 ^'T G Q���w1 BIOFILTER 2 IN POND 10 .065 .2766 1.90 INTO THE s.7� `-+i'�1 BIOFILTER 2 IN POND 100 .105 .2766 2.72 MA AW AM air 4.0 S/N: 07YXYWJN4T12 Bentley Systems, Inc. PondPack (10.00.016.00) 4:34 PM 10/22/2009 Type. . . . Master Network Summary Page 1.03 Name. . . . Watershed File. . . . J:\PROJECT\2008proj\08107 CHO Offset LOC\Design\08107 Area 2.ppw w. MASTER NETWORK SUMMARY Modified Rational Method Network (*Node=Outfall; +Node=Diversion;) rr (Trun= HYG Truncation: Blank=None; L=Left; R=Rt; LR=Left&Rt) •" Max Return HYG Vol Qpeak Qpeak Max WSEL Pond Storage Node ID Type Event ac-ft Trun hrs cfs ft ac-ft 00 BIOFILTER 2 OUT POND 2 .019 .4702 .89 589.22 .032 BIOFILTER 2 OUT POND 10 .041 .4426 1.65 589.34 .035 BIOFILTER 2 OUT POND 100 .080 .4702 2.67 589.46 .040 AW *OUT 10 JCT 2 .019 .4702 .89 *OUT 10 JCT 10 .041 .4426 1.65 *OUT 10 JCT 100 .080 .4702 2.67 .. PEAK FLOW RATE OUT of DROWSED BASIN. ANII QZ C aoST1= 0.89 CFS Qz ( ) .7. 1. 22 CFS Q►o (t sT) = L S CFS aio (FRE)r- I . yv FS Alik AIO S/N: 07YXYWJN4T12 Bentley Systems, Inc. PondPack (10.00.016.00) 5:02 PM 10/22/2009 .. Type. . . . Tc Calcs Page 2.01 Name. . . . AREA 2 Tag: PRE goo File. . . . J:\PROJECT\2008proj\08107 CHO Offset LOC\Design\08107 Area 2.ppw 4010 PRE-DEvELOPED TIME OF CONCENTRATION CALCULATOR SEE PRE-DEVELbPE© DRAINAGE AREA MAP (EXHIBIT z) FOR Ft.&)PATH'. Segment #1: Tc: TR-55 Sheet Mannings n .2400 W Hydraulic Length 92.00 ft 2yr, 24hr P 3.7000 in Slope .040000 ft/ft Avg.Velocity .16 ft/sec Segment #1 Time: .1568 hrs Segment #2: Tc: TR-55 Channel Flow Area 2.0000 sq.ft Wetted Perimeter 8.12 ft Hydraulic Radius .25 ft Slope .040000 ft/ft Mannings n .0300 ,, Hydraulic Length 247.00 ft Avg.Velocity 3.90 ft/sec ,,,. Segment #2 Time: .0176 hrs Air Total Tc: .1744 hrs NW ar. +rn ..r S/N: 07YXYWJN4T12 Bentley Systems, Inc. PondPack (10.00.016.00) 4:34 PM 10/22/2009 .r Type. . . . Tc Calcs Page 2.02 Name. . . . AREA 2 Tag: POST .` File. . . . J:\PROJECT\2008proj\08107 CHO Offset LOC\Design\08107 Area 2.ppw POST DEVELOPMENT TIME OF CONCENTRATION CALCULATOR «.r SEE POST DEVELOPMENT DRAMNA&E AREA MA? FM ROW PATH. Segment #1: Tc: TR-55 Sheet Mannings n .2400 0 Hydraulic Length 63.00 ft 2yr, 24hr P 3.7000 in Slope .020000 ft/ft ,,. Avg.Velocity .11 ft/sec Segment #1 Time: .1528 hrs .0 Segment #2: Tc: TR-55 Sheet Mannings n .2400 .., Hydraulic Length 87.00 ft 2yr, 24hr P 3.7000 in Slope .250000 ft/ft „• Avg.Velocity .34 ft/sec Segment #2 Time: .0720 hrs Segment #3: Tc: Length & Vel. Hydraulic Length 240.00 ft ar Avg.Velocity 1.29 ft/sec Segment #3 Time: .0517 hrs Total Tc: .2766 hrs wr ,wr IWO S/N: 07YXYWJN4T12 Bentley Systems, Inc. PondPack (10.00.016.00) 4:34 PM 10/22/2009 Type. . . . Vol: Elev-Area Page 3.01 Name. . . . BIOFILTER 2 Ad File. . . . J:\PROJECT\2008proj\08107 CHO Offset LOC\Design\08107 Area 2.ppw Elevation Planimeter Area Al+A2+sqr(Al*A2) Volume Volume Sum (ft) (sq.in) (acres) (acres) (ac-ft) (ac-ft) r 588.00 .0200 .0000 .000 .000 589.00 .0300 .0745 .025 .025 590.00 .0400 .1046 .035 .060 NOTE: THESE c-ALCULATVAIS DO NOT CONS I OEIR INFILTRATION 1K006-1-1 THE Q►oFIL1€R . a INN Aim S/N: 07YXYWJN4T12 Bentley Systems, Inc. PondPack (10.00.016.00) 4:34 PM 10/22/2009 Type. . . . Outlet Input Data Page 4.01 Name. . . . Outlet 1 Atal File. . . . J:\PROJECT\2008proj\08107 CHO Offset LOC\Design\08107 Area 2.ppw REQUESTED POND WS ELEVATIONS: ,011 Min. Elev.= 588.00 ft Increment = .10 ft Max. Elev.= 590.00 ft awr ********************************************** OUTLET CONNECTIVITY ********************************************** ---> Forward Flow Only (UpStream to DnStream) <--- Reverse Flow Only (DnStream to UpStream) <---> Forward and Reverse Both Allowed Structure No. Outfall El, ft E2, ft Weir-Rectangular WO ---> TW 589.000 590.000 rr TW SETUP, DS Channel ■rr rwr gra 414 AIM a A. S/N: 07YXYWJN4T12 Bentley Systems, Inc. PondPack (10.00.016.00) 9:57 AM 10/22/2009 a AW Type. . . . Outlet Input Data Page 4.02 Name. . . . Outlet 1 .. File. . . . J:\PROJECT\2008proj\08107 CHO Offset LOC\Design\08107 Area 2.ppw w OUTLET STRUCTURE INPUT DATA Structure ID = WO Structure Type = Weir-Rectangular # of Openings = 1 Crest Elev. = 589.00 ft Weir Length = 6.00 ft ... Weir Coeff. = 3.000000 Weir TW effects (Use adjustment equation) Structure ID = TW Structure Type = TW SETUP, DS Channel FREE OUTFALL CONDITIONS SPECIFIED err CONVERGENCE TOLERANCES. . . Maximum Iterations= 40 Min. TW tolerance = .01 ft Max. TW tolerance = .01 ft 0. Min. HW tolerance = .01 ft Max. HW tolerance = .01 ft Min. Q tolerance = .00 cfs Max. Q tolerance = .00 cfs +.t owl USW AW AW MW S/N: 07YXYWJN4T12 Bentley Systems, Inc. PondPack (10.00.016.00) 9:57 AM 10/22/2009 Type. . . . C and Area Page 5.01 Name. . . . AREA 2 Tag: PRE mom File. . . . J:\PROJECT\2008proj\08107 CHO Offset LOC\Design\08107 Area 2.ppw API RATIONAL C COEFFICIENT DATA pKG-DtVE E �- SEE PRE-DEVELOPED DRAINAGE AREA MAP (LEXN1811 4 FOR GR0uND coV6 Area C x Area Soil/Surface Description C acres acres Grass .3000 .810 .243 Impervious .9000 .060 .054 WEIGHTED C & TOTAL AREA ---> .3414 .870 .297 a AW Aft MA r a A a A. S/N: 07YXYWJN4T12 Bentley Systems, Inc. PondPack (10.00.016.00) 4:34 PM 10/22/2009 a Type. . . . C and Area Page 5.02 Name. . . . AREA 2 Tag: POST File. . . . J:\PROJECT\2008proj\08107 CHO Offset LOC\Design\08107 Area 2.ppw Ale RATIONAL C COEFFICIENT DATA POST DEVLOPEMENT 'SEE QST D&"'VELoPEMEN'[ DRAINR(3•E AREA 11APLE4415113)_ FoR frROND COVER. air Area C x Area Soil/Surface Description C acres acres Grass .3000 1.250 .375 11101 Impervious .9000 .150 .135 WEIGHTED C & TOTAL AREA ---> .3643 1.400 .510 Mr ARV AUM r.r Ada +.r err rr S/N: 07YXYWJN4T12 Bentley Systems, Inc. PondPack (10.00.016.00) 4:34 PM 10/22/2009 Type. . . . C and Area Page 5.02 Name. . . . AREA 2 Tag: POST File. . . . J:\PROJECT\2008proj\08107 CHO Offset LOC\Design\08107 Area 2.ppw LI Type. . . . Rational Predev. Peak Q Page 5.03 Name. . . . AREA 2 Event: 2 yr File. . . . J:\PROJECT\2008proj\08107 CHO Offset LOC\Design\08107 AREA 2.PPW ;,,. Storm. . . e, b, d Tag: Dev 2 SUMMARY OF RATIONAL METHOD PEAK DISCHARGES m. - PREDEVELOPED CONDITIONS --- Q = CiA * Units Conversion; Where Conversion = 43560 / (12 * 3600) rr Tag Freq File IDF Curve ,., Dev 2 2 e = 1.0000 b = 106.0200 d = 15.5100 Tc = .1744 hrs Tag Freq C C adj I C I Area I Peak Q (years) factor I final in/hr acres I cfs Dev 2 2 .341 1.000 I .341 4.0819 .870 I 1 1.22 1 .r 410 re) - PEAK FL.J RATE OF PRE-bEVeLOPE) m. GONDITIc 4S. a S/N: 07YXYWJN4T12 Bentley Systems, Inc. PondPack (10.00.016.00) 4:34 PM 10/22/2009 a ` Type. . . . C and Area Page 5.02 Name. . . . AREA 2 Tag: POST File. . . . J:\PROJECT\2008proj\08107 CHO Offset LOC\Design\08107 Area 2.ppw aar 0 Type. . . . Mod. Rational Graph Page 5.04 Name. . . . AREA 2 Tag: Dev 2 Event: 2 yr File. . . . J:\PROJECT\2008proj\08107 CHO Offset LOC\Design\08107 AREA 2.PPW Asa Storm. . . e, b, d Tag: Dev 2 MODIFIED RATIONAL METHOD ar ---- Graphical Summary for Maximum Required Storage ---- Method I „r Q = CiA * Units Conversion; Where Conversion = 43560 / (12 * 3600) ********************************************************************** ., * RETURN FREQUENCY: 2 yr I Allowable Outflow- 1.22 cfs , * 'C' Adjustment: 1.000 I Required o Strage .012 ac-ft * * * Peak Inflow: 1.45 cfs a * .HYG File: Dev 2 ********************************************************************** Q1 Td = .3667 hrs ( Return Freq: 2 yr / Approx. Duration for Max. Storage / C adj .factor:1.000 air Tc= .2766 hrs I = 3.3024 in/hr Area = 1.400 acres . Q = 1.70 cfs Weighted C = .364 ✓r . I . Adjusted C = .364 . Required Storage 6012 a -ftt Td= .3667 hrs • 1 1 I = 2.8264 in/hr xxxxxxxlxxxxxxxxxxx Q = 1.45 cfs • x x ..a o Q = 1.22 cfs . x o x (Allow.Outflow) . x o . x o NOT TO SCALE x ,rr . x o o x .4106 hrs T Wr OWN S/N: 07YXYWJN4T12 Bentley Systems, Inc. PondPack (10.00.016.00) 4:34 PM 10/22/2009 M" Type. . . . Mod. Rational Storm Calcs Page 5.05 Name. . . . AREA 2 Tag: Dev 2 Event: 2 yr File. . . . J:\PROJECT\2008proj\08107 CHO Offset LOC\Design\08107 Area 2.ppw Storm. . . e, b, d Tag: Dev 2 met MODIFIED RATIONAL METHOD ---- Summary for Single Storm Frequency ---- a Q = CiA * Units Conversion; Where Conversion = 43560 / (12 * 3600) RETURN FREQUENCY: 2 yr 'C' Adjustment = 1.000Allowable Q = 1.22 cfs mo Hydrograph Storm Duration, Td = .3667 hrs Tc = .2766 hrs Hydrograph File: Dev 2 aM VOLUMES Wtd. Adjusted Duration Intens. Area Qpeak I Inflow Storage 'C' 'C' hrs in/hr acres cfs 1 ac-ft ac-ft Sib .364 .364 .2766 3.3024 1.400 1.70 1 .039 .011 .364 .364 .3333 2.9856 1.400 1.54 1 .042 .011 ************************************************************ Storage Maxim .364 .364 .3667 2.8264 1.400 1.45 1 .044 .01 **************************************************************************** .364 .364 .5000 2.3296 1.400 1.20 1 Qpeak < Qallow 41111 a AIMS a a a S/N: 07YXYWJN4T12 Bentley Systems, Inc. PondPack (10.00.016.00) 4:34 PM 10/22/2009 a AO Type. . . . Rational Predev. Peak Q Page 5.06 Name. . . . AREA 2 Event: 10 yr File. . . . J:\PROJECT\2008proj\08107 CHO Offset LOC\Design\08107 Area 2.ppw aim Storm. . . e, b, d Tag: Dev 10 ANS SUMMARY OF RATIONAL METHOD PEAK DISCHARGES --- PREDEVELOPED CONDITIONS --- am Q = CiA * Units Conversion; Where Conversion = 43560 / (12 * 3600) a,. Tag Freq File IDF Curve Dev 10 10 e = 1.0000 b = 161.6000 d = 18.7300 Tc = .1744 hrs Tag Freq C C adj I C I Area I Peak Q ,.. (years) factor I final in/hr acres I cfs I Dev 10 10 .341 1.000 I .341 5.5355 .870 I 1.66 so (///) PEAK FLOW RATE a PRE- DEVELOPED CONDITIONS . MA NINI aor S/N: 07YXYWJN4T12 Bentley Systems, Inc. PondPack (10.00.016.00) 4:34 PM 10/22/2009 Type. . . . Rational Predev. Peak Q Page 5.06 Name. . . . AREA 2 Event: 10 yr File. . . . J:\PROJECT\2008proj\08107 CHO Offset LOC\Design\08107 Area 2.ppw Storm. . . e, b, d Tag: Dev 10 .. ❑ Type. . . . Mod. Rational Graph Page 5.07 Name. . . . AREA 2 Tag: Dev 10 Event: 10 yr File. . . . J:\PROJECT\2008proj\08107 CHO Offset LOC\Design\08107 AREA 2.PPW Storm. . . e, b, d Tag: Dev 10 MODIFIED RATIONAL METHOD ---- Graphical Summary for Maximum Required Storage ---- Method I ar. Q = CiA * Units Conversion; Where Conversion = 43560 / (12 * 3600) ********************************************************************** ee� .0 * RETURN FREQUENCY: 10 yr I Allowable Outflow: 1.66 cfs ----;-PRE * 'C' Adjustment: 1.000 1 .Reaued Storage: 018 ac-ft _r . * Peak Inflow: 1.90 cfs * w * .HYG File: Dev 10 * ********************************************************************** ar Q 1 Td = .4167 hrs I Return Freq: 10 yr / Approx. Duration for Max. Storage / C adj.factor:1.000 ,.r Tc= .2766 hrs I = 4.5748 in/hr Area = 1.400 acres . Q = 2.35 cfs Weighted C = .364 a.. • 1 • Adjusted C = .364 . I • Required Storage .-- .018 ac-ft Td= .4167 hrs • 1 I I = 3.6954 in/hr • xxxxxxxlxxxxxxxxxxx Q = 1.90 cfs 6""" POSTUN • x x vow Q = 1.66 cfs PRE • x o x (Allow.Outflow) 1` . x o . x o NOT TO SCALE x min . x o 0 x .4520 hrs T min Ar. S/N: 07YXYWJN4T12 Bentley Systems, Inc. PondPack (10.00.016.00) 4:34 PM 10/22/2009 .r Type. . . . Mod. Rational Storm Calcs Page 5.08 Name. . . . AREA 2 Tag: Dev 10 Event: 10 yr File. . . . J:\PROJECT\2008proj\08107 CHO Offset LOC\Design\08107 Area 2.ppw mr MODIFIED RATIONAL METHOD ---- Summary for Single Storm Frequency ---- mil Q = CiA * Units Conversion; Where Conversion = 43560 / (12 * 3600) RETURN FREQUENCY: 10 yr 'C' Adjustment = 1.000Allowable Q = 1.66 cfs t""--* ARE ar Hydrograph Storm Duration, Td = .4167 hrs Tc = .2766 hrs Hydrograph File: Dev 10 am VOLUMES Wtd. Adjusted Duration Intens. Area Qpeak I Inflow Storage 'C' 'C' hrs in/hr acres cfs ac-ft ac-ft rr .364 .364 .2766 4.5748 1.400 2.35 .054 .016 .364 .364 .3333 4.1725 1.400 2.15 .059 .017 ************************************************ ********* Storage Maximum .364 .364 .4167 3.6954 1.400 1.90 .065 .018 ***************************************************** ********************* .364 .364 .5000 3.3162 1.400 1.71 .070 .017 .364 .364 .6667 2.7516 1.400 1.42 Qpeak < Qallow POST iN aw *4111 AO MO` S/N: 07YXYWJN4T12 Bentley Systems, Inc. PondPack (10.00.016.00) 4:34 PM 10/22/2009 ar VIRGINIA EROSION AND SEDIMENT CONTROL REGULATONS CHAPTER 1 15. The bed and banks of a watercourse shall be stabilized immediately after work in the watercourse is completed. 16. Underground utility lines shall be installed in accordance with the following standards in addition to other applicable criteria: a. No more than 500 linear feet of trench may be opened at one time. b. Excavated material shall be placed on the uphill side of trenches. c. Effluent from dewatering operations shall be filtered or passed through an approved sediment trapping device, or both, and discharged in a manner that does not adversely affect flowing streams or off-site property. d. Material used for backfilling trenches shall be properly compacted in order to minimize erosion and promote stabilization. e. Restabilization shall be accomplished in accordance with these regulations. f. Applicable safety regulations shall be complied with. 17. Where construction vehicle access routes intersect paved or public roads,provisions shall be made to minimize the transport of sediment by vehicular tracking onto the paved surface. Where sediment is transported onto a paved or public road surface, the road surface shall be cleaned thoroughly at the end of each day. Sediment shall be removed from the roads by shoveling or sweeping and transported to a sediment control disposal area. Street washing shall be allowed only after sediment is removed in this manner. This provision shall apply to individual development lots as well as to larger land-disturbing activities. 18. All temporary erosion and sediment control measures shall be removed within 30 days after final site stabilization or after the temporary measures are no longer needed,unless otherwise authorized by the local program authority.Trapped sediment and the disturbed soil areas resulting from the disposition of temporary measures shall be permanently stabilized to prevent further erosion and sedimentation. MS- V) V\REM ENT5 * 19. Properties and waterways downstream from development sites shall be protected from sediment deposition, erosion and damage due to increases in volume,velocity and peak flow rate of stoiniwater runoff for the stated frequency storm of 24-hour duration in accordance with the following standards and criteria: a. Concentrated stormwater runoff leaving a development site shall be discharged directly into an adequate natural or man-made receiving channel,pipe or storm sewer system. For those sites where runoff is discharged into a pipe or pipe system, 1-39 VJRGINIA:EROSION AND SEDIMENT CONTROL REGULATONS CHAPTER 1 downstream stability analyses at the outfall of the pipe or pipe system shall be performed. b. Adequacy of all channels and pipes shall be verified in the following manner: (1) The applicant shall demonstrate that the total drainage area to the point of analysis within the channel is one hundred times greater than the contributing drainage area of the project in question; or (2) (a) Natural channels shall be analyzed by the use of a two-year storm to verify that stou�iwater will not overtop channel bs n ankor cause erosion of channel bed or banks; and (b) All previously constructed man-made channels shall be analyzed by the use of a ten-year storm to verify that stormwater wilLnot overtop i banks and by the use of a two-year storm to demonstrate that stormwater will not cause erosion of channel bed or banks; and (c) Pipes and storm sewer systems shall be analyzed by the use of a ten-year stothat stormwater will be contained wh ithin te p' or system. c. If existing natural receiving channels or previously constructed man-made channels or pipes are not adequate, the applicant shall: (1) Improve the channel to a condition where a ten-year storm will not overtop the banks and a two-year storm will not cause erosion to the channel bed or banks; or (2) Improve the pipe or pipe system to a condition where the ten-year storm is contained within the appurtenances; or (3) Develop a site design that will not cause the pre-development peak runoff rate from a two-year storm to increase when runoff outfalls into a natural channel or will not cause the pre-development peak runoff rate from a ten-year storm to increase when runoff outfalls into a man-made channel; or (4) Provide a combination of channel improvement, stormwater detention or other measures which is satisfactory to the plan-approving authority to prevent downstream erosion. d. The applicant shall provide evidence of permission to make the improvements. e. All hydrologic analyses shall be based on the existing watershed characteristics and the ultimate development of the subject project. a 1-40 VIRGINIA EROSION AND SEDIMENT CONTROL REGULATONS:` CHAPTER 1 _... Of$.4L9 1,KMA4AS4 ,t 1.4.YbC ,3,,,,:'Nbi3; N NM I f. If the applicant chooses an option that includes stormwater detention he shall obtain approval from the locality of a plan for maintenance of the detention facilities. The plan shall set forth the maintenance requirements of the facility and the person responsible for performing the maintenance. g. Outfall from a detention facility shall be discharged to a receiving channel, and energy dissipators shall be placed at the outfall of all detention facilities as necessary to provide a stabilized transition from the facility to the receiving channel. h. All on-site channels must be verified to be adequate. I. Increased volumes of sheet flows that may cause erosion or sedimentation on adjacent property shall be diverted to a stable outlet, adequate channel,pipe or pipe system, or to a detention facility. j. In applying these stormwater runoff criteria,individual lots or parcels in a residential, commercial or industrial development shall not be considered to be separate development projects. Instead,the development, as a whole, shall be considered to be a single development project. Hydrologic parameters that reflect the ultimate development condition shall be used in all engineering calculations. VOW k. All measures used to protect properties and waterways shall be employed in a manner which minimizes impacts on the physical,chemical and biological integrity of rivers, streams and other waters of the state. §4VAC50-30-50 Variances. The plan-approving authority may waive or modify any of the regulations that are deemed inappropriate or too restrictive for site conditions,by granting a variance. A variance may be granted under these conditions: .,.. 1. At the time of plan submission, an applicant may request a variance to become part of the approved erosion and sediment control plan. The applicant shall explain the reasons for requesting variances in writing. Specific variances which are allowed by the plan-approving authority shall be documented in the plan. 2. During construction, the person responsible for implementing the approved plan may request a variance in writing from the plan-approving authority. The plan-approving authority shall respond in writing either approving or disapproving such a request. If the plan-approving authority does not approve a variance within 10 days of receipt of the request, the request shall be considered to be disapproved. Following disapproval, the applicant may resubmit a variance request with additional documentation. a 3. The plan-approving authority shall consider variance requests judiciously, keeping in a 1-41 a mai stall APPENDIX"5" WATER QUALITY CALCULATIONS a 10/22/2009 4:28 PM WATER QUALITY CALCULATIONS REMOVAL RATE CALCULATIONS Charlottesville-Albemarle Airport Charlottesville,Virginia Delta Project No.VA 08107 Date:OCTOBER 12,2009 DEVELOPMENT AREA#1 Lpre=8.77`(.05+.9'Ipre)Cw*A +sirs Lpost=8.77'(.05+.9*Ipost)*Cw*A RR=(Lpost-Lpre)`100/Lpost Cw(Drinking Watershed)=0.35 Impervious Cover:Pre-development Land Use Equivalent%Impervious Cover Contributing Area,A(ac) Impervious Area,Ipre(ac) Grass 8 0.32 0.03 Gravel 100 0.05 0.05 Pavement 100 0.00 0.00 Total= 0.37 0.08 aaw Lpre=0.13 a Impervious Cover:Post-development Land Use Equivalent%Impervious Cover Contributing Area,A(ac) Impervious Area,(post(ac) Grass 8 0.68 0.05 Gravel 100 0.07 0.07 Pavement 100 0.00 0.00 rr Total= 0.75 0.12 Lpost=0.37 a RR=64.0% DEVELOPMENT AREA#2 err Impervious Cover:Pre-development Land Use Equivalent%Impervious Cover Contributing Area,A(ac) Impervious Area,Ipre(ac) Grass 8 0.81 0.06 aire Gravel 100 0.06 0.06 Pavement 100 0.00 0.00 Total= 0.87 0.12 Lpre=0.79 a Impervious Cover:Post-development Land Use Equivalent%Impervious Cover Contributing Area,A(ac) Impervious Area,Ipost(ac) Grass 8 1.25 0.10 Gravel 100 0.15 0.15 Pavement 100 0.00 0.00 a Total= 1.40 0.25 Lpost=2.16 ANS RR=63.3% aaa J:\PROJEC112008pro1108107 CHO Offset LOC\Design\08107 Removal Rates_02 Page 1 rare jdb Page 1 10/21/2009 BIOFILTER BASIN DESIGN Charlottesville-Albemarle Airport Charlottesville,Virginia Delta Project No.VA 08107 Biofilter#1 Target Phosphorus Removal Efficiency=65% Treatment Volume=1"per contributing impervious acre Basin Surface Area=5.0%(min)of contributing impervious area Ponding Depth=1'(max) Biofilter Dimensions aie Area of Contributing Impervious Area= 0.12 ACRES *See Water Quality Calculations Basin Surface Area Required= 0.01 ACRES Basin Surface Area Provided= 0.01 ACRES eor Basin Volume Required= 0.01 AC-FT Basin Volume Provided= 0.03 AC-FT *Volume includes all storage volume up to stone weir Final Biofilter Dimensions= 17 x 15'x 1' mss Planting Design Planting Density= 400 stems/acre Plants Required at 400 stems/acre= 4 Recommended Tree to Shrub Ratio= 3:1 Shrubs Required with Ratio= 3 Trees Required with Ratio= 1 err Due to FAA restrictions on planting trees in airside development,required trees will be replaced with 2 shrubs each. Final Number of Shrubs Required= 5 Plants Provided= 5 4ee FINAL PLANTING SCHEDULE COMMON NAME SCIENTIFIC NAME NUMBER PLANTING HIEGHT(FT) MATURE HEIGHT(ft) SYMBOL HORIZONTAL JUNIPER Juniperus spp 2 3-4 OR 18"-24"SPREAD 1-2 HJ SWEET FERN Comptonia peregrina 2 3-4 OR 18"-24"SPREAD 2-4 SF COMMON JUNIPER Juniperus communis"compressa" 1 3-4 OR 18"-24"SPREAD 3-6 CJ Note: Shrubs shall be planted at a maximum of 12'apart. vr+ Ground cover shall be planted approximately 2'apart and away from shrubs. ar moo a ar a J:\PROJECT\2008proj\08107 CHO Offset LOC\Design\08107 Biofilters jdb Page 2 10/21/2009 BIOFILTER BASIN DESIGN Charlottesville-Albemarle Airport Charlottesville,Virginia Delta Project No.VA 08107 Biofilter#2 Target Phosphorus Removal Efficiency=65% Treatment Volume=1"per contributing impervious acre "" Basin Surface Area=5.0%(min)of contributing impervious area Ponding Depth=1'(max) Biofilter Dimensions war Area of Contributing Impervious Area= 0.25 ACRES 'See Water Quality Calculations Basin Surface Area Required= 0.01 ACRES Basin Surface Area Provided= 0.03 ACRES AIN Basin Volume Required= 0.01 AC-FT Basin Volume Provided= 0.03 AC-FT 'Volume includes all storage volume up to stone weir Final Biofilter Dimensions= 35'x 15'x 1' wM Planting Design Planting Density= 400 stems/acre 41111.1 Plants Required at 400 stems/acre= 4 Recommended Tree to Shrub Ratio= 3:1 Shrubs Required with Ratio= 3 Trees Required with Ratio= 1 r Due to FAA restrictions on planting trees in airside development,required trees will be replaced with 2 shrubs each. Final Number of Shrubs Required= 5 Plants Provided= 5 ram FINAL PLANTING SCHEDULE COMMON NAME SCIENTIFIC NAME NUMBER PLANTING HIEGHT(FT) MATURE HEIGHT(ft) SYMBOL HORIZONTAL JUNIPER Juniperus spp 2 3-4 OR 18"-24"SPREAD 1-2 HJ SWEET FERN Comptonia peregrina 2 3-4 OR 18"-24"SPREAD 2-4 SF COMMON JUNIPER Juniperus communis"compressa" 1 3-4 OR 18"-24"SPREAD 3-6 CJ Note: Shrubs shall be planted at a maximum of 12'apart. sr Ground cover shall be planted approximately 2'apart and away from shrubs. aar ram S ram 4- arm J:\PROJECT\2008proj\08107 CHO Offset LOC\Design\08107 Biofilters awa MINIMUM STANDARD 311 CHAPTER 3 Stt1lgf MD PLANTfllG CrtiMANCE The grass buffer strip filters particles from the runoff and reduces its velocity. The sand bed further slows the velocity of the runoff, spreads the runoff over the basin, filters part of the water, provides for positive drainage to prevent anaerobic conditions in the planting soil and enhances exfiltration from the basin. The ponding area functions as storage of runoff awaiting treatment and as a presettling basin for particulates that have not been filtered out by the grass buffer. The organic or mulch layer acts as a filter for pollutants in the runoff, protects the soil from eroding , and provides an environment for microorganisms to degrade petroleum-based solvents and other pollutants. The planting soil layer nurtures the plants with stored water and nutrients. Clay particles in the soil adsorb heavy metals,nutrients,hydrocarbons, and other pollutants. The plant species are selected based on their documented ability to cycle and assimilate nutrients,pollutants, and metals through the interactions among plants, soil, and the organic layer(ibid). By providing a variety of plants, monoculture susceptibilities to insect and disease infestation are avoided, and evapotranspiration is enhanced. The vented infiltration chambers provide unobstructed exfiltration through the open-bottomed cavities,decrease the ponding time above the basin,and aerate the filter media between storms through the open chamber cavities and vents to grade, preventing the development of anaerobic conditions. By providing a valve equipped drawdown drain to daylight, the basin can be converted into a soil media filter should exfiltration surface failures occur. Perforated underdrain systems are recommended for facilities placed in residential areas and in all areas where the in-situ soils are questionable. Refer to 3.11A-Bioretention Filter. The minimum width for a bioretention area is usually 10 feet, although widths as narrow as 4 feet may be used if the runoff arrives as dispersed sheet flow along the length of the facility from a properly sized vegetated strip. The minimum length should be 15 feet(for lengths greater than 20 feet,the length should be at least twice the width to allow dispersed sheet flow). As an infiltration BMP,the maximum ponding depth is restricted to six inches to restrict maximum ponding time to preclude development of anaerobic conditions in the planting soil(which will kill the plants)and to prevent the breeding of mosquitoes and other undesirable insects in the ponded water. The planting soil must have sufficient depth to provide appropriate moisture capacity, create space for the root systems, and provide resistance from windthrow (Minimum depth equal to the diameter of the largest plant root ball plus 4 inches). Table 3.11-1 contains the target removal efficiencies once a mature plant community is created in the bioretention . eas based on the volume of runoff to be captured and infiltered. Flood Control and Channel Erosion D TER INS �F1t Nc ' The amount of flood and channel erosion dl proTi BdSy Mi tendo ibginsc p`nd"s o i' e"K N S local rainfall frequency spectrum, the amount of pre-development (or pre-redevelopment) impervious cover, the amount of post-development impervious cover, and the volume of runoff captured and infiltered by the basin(s). The effect of the BMPs on peak flow rates from the drainage shed must be examined. As with other infiltration practices,bioretention basins tend to reverse the consequences of urban development by reducing peak flow rates and providing groundwater discharge. 3.11-3 MINIMUM STANDARD 3.11 CHAPTER 3 TABLE 3.11-1 Pollutant Removal Efficiencies for Bioretention Basins Target Phosphorus BMP Description Removal Efficiency Bioretention basin with capture and treatment volume equal to 0.5 inches of runoff from the im ervious area. 0% Bioretention basin with capture and treatment volume equal to 1.0 inches of runoff from the impervious area. 65% Alrimetv- '111111110.-- (, % > %.O % >63. Conditions Where Practice Applies Bioretention basins are suitable for use on any project where the subsoil is sufficiently permeable to provide a reasonable rate of infiltration and where the water table is sufficiently lower than the design depth of the facility to prevent pollution of the groundwater. Bioretention basins are generally suited for almost all types of development, from single-family residential to fairly high density commercial projects. They are attractive for higher density projects because of their relatively high removal efficiency. Figures 3.11-2 through 3.11- 5 illustrate several applications. Bioretention basins may also be installed in off-line pockets along the drainage swales adjacent to highways or other linear projects, as illustrated in Figure 3.11-6. For large applications, several bioretention basins connected by an underground infiltration trench("Green Alleys")are preferable to a single, massive basin. Such a system is especially desirable along the landward boundary of reduced Chesapeake Bay Resource Protection Areas. Minimum Standard 3.11B discusses this system. Considering the character of bioretention basins, some jurisdictions may qualify them as buffer restoration. 3.11-4 MINIMUM STANDARD 3.11 CHAPTER 3 General Design Criteria The purpose of this section is to provide minimum criteria for the design of bioretention basin BMPs intended to comply with the Virginia Stormwater Management program's runoff quality requirements. Bioretention basins which capture and infilter the first 1 inch of runoff from impervious surfaces may also provide streambank erosion protection. General The design of bioretention basins should be in accordance with the following Minimum Standards where applicable: 3.1: Earthen Embankments, 3.2: Principal Spillways, 3.3: Vegetated Emergency Spillways,3.4:Sediment Forebay,3.10:General Infiltration Practices,and 3.10A: Infiltration Basin, as well as the additional criteria set forth below. The designer is not only responsible for selecting the appropriate components for the particular design but also for ensuring long-term operation. Soils Investigation Refer to the Planning Considerations and Design Criteria of General Infiltration Practices,MS- - - 3.10,and to local jurisdiction soil study requirements such as Chapter 5,Section V.of the Northern Virginia BMP Handbook. As with infiltration basins(MS3.10A), a minimum of one soil boring log should be required for each 5,000 square feet of bioretention basin area(plan view area)and in no case less than three soil boring logs per basin. Topographic Conditions a Like other infiltration facilities,bioretention basins should be a minimum of 50 feet from any slope greater than 15 percent. A geotechnical report should address the impact of the basin upon the steep slope(especially in marine clay areas). Also,bioretention basins should be a minimum of 100 feet up-slope and 20 feet downslope from any buildings. :asin izing Methodology In Virginia,bioretention basins are designed to exfilter the treatment quantity into the underlying soil strata, or into an underlying perforated underdrain system connected to a storm drain system or other outfall when the underlying soils,proximity to building foundation,or other such restrictions preclude the use of infiltration. When such an underdrain system is used, the facility is referred to as a Bioretention Filter- Minimum Standard 3.11A. Recent research at the University of Maryland has supported a reduction in overall d2th of the soil to 2.5 feet. Generally,the soil depth can be designed to a minimum depth equal to the diameter of the largest plant root ball plus 4 inches.The recommended soil composition was revised to reduce the clay and increase the sand content (Refer to Soil Texture and Structure later in this 3.11-13 Aim MINIMUM STANDARD 3.11 CHAPTER 3 standard). This revised soil composition also eliminated the 12" sand layer at the bottom of the facility. The researchers concluded that significant pollutant reductions are achieved in the mulch layer and the first 2 to 2.5 feet of soil. The elevation of the overflow structure should be 0.5 feet above the mulch layer of the bioretention bed. When an underdrain system is used ' . Std.3.11A the overflow can be as much as 1.0 feet above e vrie The size of the bioretention facility is dictated by the amount of impervious surface in the contributing drainage area. For facilities capturing the first 0.5 inches ofrunoff from the impervious areas in the drainage shed,the surface area of the bioretention bed should be a minimum of 2.5%of } the impervious area, or 1,090 square feet per impervious acre. For facilities ca turin the s • of runoff,the bioretention bed shotaldhe a minimum of 5. o o unbervious area or 2,180 sauzrc ee per nnpervious act (\ The minimum width and length is recommended at 10 feet and 15 feet respectively. (Widths as narrow as 4 feet may be used if the runoff arrives as dispersed sheet flow along the length of the facility from a properly sized vegetated strip). t, The elevation of the overflow structure should be 0.5 feet above the mulch elevation of the bioretention bed. Note that small projects such as single family residences may default to the minimum 10'X 15') 150 square foot area. FOR 'SIZING U Se* TABLE 3.11-4 AREA. ENURE VoLVME Basin Sizing Summary $ FILTEA IS SUFFIC' rQ oto" Treatment Volume Basin Surface Area PeR (Expressed as percentage of impervious area) MtEgalltAl 0.5"per impervious acre 2.5% 1.0 per impervious acre 5.0% o Runoff Pretreatment Like other infiltration basins,bioretention basins must always be preceded by a pretreatment facility to remove grease,oil,floatable organic material, and settleable solids (see Urban Runoff section of Sediment Control under Planning Considerations above). Where space constraints allow,runoff should be filtered by a grass buffer strip and sand bed. The buffer strip and sand bed will reduce the amount of fine material entering the bioretention area and minimize the potential for clogging of the planting soil. The sand bed also increases the infiltration capacity and provides aeration for the plant roots in the bioretention area. For basins for which high sediment loadings are expected (treating 3.11-14 4 MINIMUM STANDARD"3.11 CHAPTER 3 4. Number of Species A minimum of three species of trees and three species of shrubs should be selected to insure diversity. In addition to reducing the potential for monoculture mortality concerns, a diversity of trees and shrubs with differing rates of transpiration may ensure a more constant rate of evapotranspiration and nutrient and pollutant uptake throughout the growing season. Herbaceous ground covers are important to prevent erosion of the mulch and the soil layers. Suitable herbaceous ground covers are identified in Table 3.11-7C. 5. Number and Size of Plants The requisite number of plantings varies, and should be determined on an individual site basis. On average, 1000 trees and shrubs should be planted per acre. For example, a bioretention area measuring 15'x 40'would contain a combination of trees and shrubs totaling 14 individuals. The Prince Georges County recommended minimum and maximum number of individual plants and spacing are given in Table 3.11-4. Virginia jurisdictions with significant experience with bioretention prefer the simpler specification of 10 trees and shrubs per 1,000 square feet of basin area, with placement specified by a landscape professional to simulate natural conditions. Two to three shrubs should be specified for each tree (2:1 to 3:1 ratio of shrubs to trees). At installation,trees should be 1.0 inches minimum in caliper,and shrubs 3 to 4 feet in 1 24 to inches in spread per AS Z6n_ Ground cover ma be as see or re era l lu s. The relatively mature size requirements for trees an s s are important to ensurer that the installation of plants are readily contributing to the bioretention process (i.e., evapotranspiration, pollutant uptake). T _r Recommended Tree and Shrub S acin Tree Spacing(feet) Shrub Spacing(feet) Total Density (sSems/acre) Maximum 19 12 400 Average 12 8 1000 Minimum 11 7 1250 OSE 400 ITEMS /Ptc. E , REWM ENOE1 6. Plant Layout TRS ARE TO B REPLICID 10'( NAUSS oe€ To The layout of plant material can be a flexible process; however, the designer should follow some FAA basic guidelines. As discussed above,the designer should first review the Plant Checklist(Appendix D). The checklist table can help expose any constraints that may limit the use of a particular specie $$ja and/or where a species can be installed. There are two guidelines that should apply to all bioretention areas. First, woody plant material 3.11-20 From A 1 be.wtar Ie Co Lott/ ..s1:,14 Manta / iOUTLET 6 NON-PERFORATED PROTECTION PVC PIPE TO +yte OVERFLOW DAYLIGHT— :• PROTECTION �,, I# STONE WEIR REBUILD AS NECESSARY irr I 71 0. i f it ) 3:1 SIDE t I1 I4 SLOPES i I 1 I I 1 (MAX) r j I 11 i 1 4"-6'PERFORATED PVC PIPE SCHEDULE 40 OR APPROVED I I i i EQUIVALENT PLACED 20 R,O.C. II 11 I, � 11 I 4 { ' l II 1 I II II II I1 OUTI ET 1 e ti if *) PROTECTION! II ri f � � ENERGY 0 I I t y�i DISSIPATER p lip . i t i 1 1, STORM I r I I I •..1; WATER CHANNEL ;,<• d d �;,;._s.. CLEAN-OUT 111 (TYP) PLAN TOP OF WEIR SIDE SLOPE REGRADED BERM TO 3;1(MAX) 7 l _______ f 1 1 6.,t01' BIOFILTER MIX PER 2 �. r STATE STANDARDS (MIN) E. ;MIN) ...,. 1 ..•+:..r%..�.,- :a .•a* .. f UNDERURAIN GRAVEL (PASHTO M43, ORIGINAL SILT 1/2"-1")WRAPPED TRAP SIDESLOPE IN FILTER FABRIC PROVIDE PIPES REMOVE SILT AND ACROSS ENTIRE WIDTH SEDIMENT AFTER FINAL AT 20 FT O.C. STABILIZATION.REPLACE WITH LOAM OR GRANULAR NOTE: PROFILE STH FILL. THE DISTANCE BETWEEN CLEAN-OUTS WILL NOT EXCEED TOP OF BERM SD ttt I CLEAN-OUT 6"to 1' W/WATERTIGHT 6" CAP WEIR ---N 1 i\lif ---N7 gu ys,:r1,Lt� � `rte 6"NON-PERFORATED AIMIIIIIIIIIIPW PVC PIPE @ I%MIN,SLOPE 20 It.O.C. � . LOAM OR GRANULAR EARTHFILL 6"a 1 MIN SLOPE PIPE CROSS SECTION SILT TRAP RETROFIT TO BIO-FILTER NO SCALE ON sea APPENDIX"6" PROJECT BID TABULATIONS a a • 88888888888888888888 8 i 2'"'8 44agi 442a814una of _. 8 O U g $$”$4i888�888888in8888i- ? f J N i /uF i 888888888888888888888 F§§§§§31gs$go s g § ifigaa w p1w N w N F ix w w z 888888888888888888888 »N» -ggg .A Haw» �" ,sui 15 O 0 m U Z p L a Y ? m U W (a'J q o� Oa wz u55 B4 2Uw U p H Z Z O L.'1-''' a 6 8 U 4 1111 o �W Ja zz� m� 4.4 0 0 'rix J o03 J 0 0 < ¢ gUwm z ��� ¢07y W E 2 ¢ @ O A o¢ 6 w w o FZ uj c f r f ,1yLLUOmNzF naUtilii m o 8 z o¢LL Zw t]U� N mwUUQ `m m .> .< Z R O y 4�'o? y y g wg Wgg i c7 z w 0 W o d -,ow 55u' _ 8 _c>c�]]_zx�0a= u F NwN ww iE W W Ummm Omf 3Ntiv c�a 3 ;i F g i wp ?m5yRm0000n80.2.2P� i ¢r O <aQ a Nz ddddE.666 66 SSS,,¢ o it ag za2 0 WO _a.oaaarmm -amaNNrmmo- t� gp h4 m U< V U 2 0 0 5 Yr +rw ar rr APPENDIX"7" COMPLETED COUNTY REVIEW CHECKLIST lie w+ +ir ALBEMARLE COUNTY COMMUNITY DEVELOPMENT ENGINEERING REVIEW FINAL PLANS CHECKLIST 4411 11 Aug 2008 (Use the latest checklist at the time of submittal from www.albemarle.org) e E' "1 New plans or resubmittals-application information: (applicable to any type of plan) M A N � _o' Completed applications(SDP,WPO,etc)[18-32.4.3.2,18-32.3.9,17-203,17-303] � l tG d t r 04 application fee or resubmittal fee � O,�? "� /�1�✓� copies of federal and state permits(Army Corps,VDEQ,etc)[Policy] 1' A completed copy of the standard stormwater maintenance agreement and fee for recordation for any stormwater management facilities[17-304E] /JA copies of manufacturer's approval of the plan for any manufactured stormwater management facilities(filterra,stormfilter,sandfilter,etc.)[Policy] NA pro-rated share payment for any sites which drain to County regional stormwater management facilities. (This should have been identified with the preliminary plan/plat)[17-316] A endments: (amendments without these items may be returned without review) M the approved plan must be included in the plan set,with the specific areas of amendment clearly outlined by bubbling or circling. The approved 4.,4 plan must not otherwise be altered. A detail on a subsequent new sheet must provide the amended features as referenced in the bubbled or circled area of the approved plan. ATAT If the site is built or under construction,details on new sheets must contain accurate as-built information. Tit�nformation:(applicable to any type of plan) project title[18-32.6.6] t✓ professional seal,signed and dated for site plans,major amendments,stormwater plans,or road and drainage plans[18-32.6.1] 6/ vicinity map[18-32.6.6] Existing conditions information:(applicable to any type of plan) 1� accurate current existing topography at the time of submittal,including all existing site features,and any recent disturbances,all at a legible scale [18-32.6.6,14-302] date and source of the topographic information: All topography should be at least visually field verified by the designer within the last year[18- 32.6.6,14-302,Policy for date] benchmark location,elevation and datum for topography. An existing utility or other known position will suffice.[Policy] ✓ WPO buffer limits;100'from stream or wetland bank,200'from reservoirs,or floodplain limit if greater[17-317] /1// floodplain limits,including 100yr flood limits for any channel with a drainage area of 50+acres[I8-32.6.6d,14-302] -FEMA map and date references labeled for FEMA floodplain[Policy] Ath all existing easements(access,drainage,sight,sanitary easements,etc.)with deed book references,locations and dimensions[18-32.6.6,14-302] L all slopes 25%and over(critical slopes by County Zoning Ord.)are shaded[18-32.6.6,14-302] Proposed plan view information:(applicable to final site plans, road and drainage plans) Grading:[18-32.6.6,14-303] proposed topography at minimum 2'contour intervals—tied into existing contours,as well as all proposed site features.(Sites with less than 6'of grade change should consider using smaller contour intervals.) proposed slopes are all 2:1(horizontal:vertical)or flatter[Policy] ,VA proposed slopes steeper than 3:1 have low maintenance(not grass)ground cover specified on the plan[Policy] existing critical(25%)slopes are not disturbed,unless a waiver has been granted by the Planning Commission for the disturbance. [18-4.2,14-304] retaining walls labeled with maximum height(walls require building permits according to Building Official policy) safety railing shown for retaining walls over 4'high(building permit may be more strict)[Policy] guardrail with VDOT designations shown for retaining walls next to parking or travelways[18-32.7.2] Easements:[18-32.7.4, Subdivision Ordinance,Article IV,Division 4] A/4 all proposed permanent easements,dimensioned and labeled Examples of easements are: NA sidewalk easements for sidewalks to be maintained with streets M private sanitary sewer easements for private lines crossing lots NA public sanitary sewer easements per ACSA drainage easements for any drainage passing through the site from off-site,or for drainage crossing proposed property lines. stormwater management easements over all facilities and associated structures and access NA access easements ,IJA intersection or entrance sight easements NA all drainage easements are a minimum 20'wide. Required width:10'+(pipe dia.or channel width)+2'+2(depth-5'). The pipe,channel or structure must be within the center third of the easement.[Policy to allow for adequate easement width for excavation] NQ no structures or trees within drainage easements[Policy to allow for excavation] EntFances and right-of-way improvements:[per VDOT Subdivision Street Requirements] all entrances with a VDOT designation(PE-1,CG-9a,etc) entrances do not exceed 4%grade for a distance of 40'from the intersected street,measured anywhere in the entrance[18-4.12.17] A ; unobstructed sight distance lines at entrances,less than 10'x Speed Limit of intersected streets,measured from a point 10'off the edge of pavement of the intersected street Al 12.5'minimum radii on entrances(or per VDOT requirements,typically 25'-35') VDOT approval is obtained for any plan affecting public right-of-way turn and taper lanes with lengths and widths labeled (taper at 12:1 with 12'lane widths) Parking and circulation:[18-4.12] 4/14 100'on-site sight distance is maintained by use of curbed islands a minimum 6'off building corners or other site obstructions. curbing on all parking areas and travelways with VDOT designations(CG-2, CG-6) loading and dumpster areas accessible at all times(not behind parking) all parking rows protected by curbed islands[Policy per 18-.4.12] minimum 3'width of curbed islands[Policy] N all edges of pavement labeled(where there is no curbing) parking areas do not exceed 5%grade anywhere,in any direction parking width x depth x aisle width is 9x 18x24'or 10x18x20' (where a 2'grass overhang is possible parking spaces can be 16'deep per detail 2) a . parallel parking spaces are 9'x20'(with a minimum aisle width of 20') Albemarle County Engineering Final Plan Checklist Page 2 of 6 N A loading spaces are 12'x25'(with a minimum aisle width of 24') i a travelways without parking are 20'wide measured from curb faces NIA parking places are separated from entrances and streets(to prevent queuing onto streets)a minimum 18'from back of the entrance radius MA sidewalk abutting parking is 6'wide(exclusive of curb),or bumper blocks are provided(see reference details) sidewalks are a minimum 5'wide,exclusive of curb one-way aisles have a 12'minimum width. (One-way circulation is only permitted when approved with a preliminary site plan) dumpster pads are 10'x10'with 8'in front for wheel bearing(total 18'depth) Drainage:[18-32.6.6d,14-305,311] (/ all proposed and existing storm sewer(with arrows indicating direction of flow where it is not otherwise evident) ✓ principle access free of flooding during the I OOyr storm " 1/ site runoff and entrances do not drain into streets ✓ concentrated runoff(1 cfs or greater)does not run across travelways [policy] k(J drainage does not run across,through,or backwater in dumpster areas[18-4.12.19] overland relief is provided for any drainage structure or inlet in case of clogging. The failure of any system will not cause structures or yards to ✓ flood.[Policy,info per 14-311,18-32.6.6s] direction of flow change(or deflection angle)in each drainage structure is 90 degrees or greater(flow should not have to reverse direction) labels on all drainage structures provided(and should match the drainage computations and profiles) /✓A provisions and easements for drainage across 3 or more lots. Dense development where fencing,decking,etc is expected should provide yard inlets and pipes rather than ditches *• Streets:[18-32.6.6,14-304,Subdivision Ordinance Article IV Division 2,VDOT Subdivision Street Requirements] all existing streets with labeled pavement and right-of-way widths,route numbers and street names 0all proposed streets,with right-of-way and street names stationing at 50'minimum on all proposed streets,matching the street profile A street horizontal curve start point,end points and radii labeled,meeting standards(see the reference details) NA turnarounds provided on all streets or alleys(see the reference details) ?i street edge of pavement or curb radii labeled at all intersections and turnarounds(see reference details) roundabouts designed per VDOT and ASHTO guidelines(see reference details) guardrail over any slope steeper than 2:1,wall,or drop-off greater than 4',with start and end sections labeled,and VDOT designations(GR-2,GR- 2a,etc.) npavement markings dimensioned and labeled N signs for traffic control shown and labeled:speed limit on all streets,stop signs at all intersections 4 street name signs at every intersection[County Road Naming and Property Numbering Ordinance and Manual] street tree locations,species and height or caliper Plan detail information: /V traffic generation and distribution summary(ADT's) pavement designs typical sections for proposed channels with locations referenced from the plan view sheets N sidewalk detail or specification to be a minimum 4"stone base and 4"concrete of 3000psi at 28 days,or stronger.[specs are policy per 14-422] /v A dumpster pad detail or specification to be a minimum 4"stone base and 6"concrete of 3000psi at 28 days,or stronger,reinforced with a minimum grid of wire reinforcing or#4 bars at 12"on center.[specs are policy] NA typical retaining wall details referenced from plan. A typical manufactures drawing for segmental block walls,or VDOT reference,is acceptable, ..* with any applicable safety railings or guardrail shown. WA details for any pipes or drainage structures through or under walls,showing endwalls,casings,or structural measures to bridge pipes or structures t✓ Albemarle County general construction notes[policy] Street profiles: (applicable only to road or street plans) stationing at 50'minimum on all proposed streets,to match the plan view sheets ✓ proposed centerline 1/ existing ground centerline Ye labeled existing and proposed grade at each 50ft station point +r+ ✓ vertical curves provided at all grade transitions t/ vertical curve start,vertex and end points labeled //S K'lake a vertical curve length and K labeled at each vertex,meeting required design values(see reference details) 1/ percent grades labeled for all road segments,meeting design values(see reference details) Am rural street intersections continue the-2%intersected cross grade for a minimum of 20'from the edge of pavement of the intersected street. A low point is provided off the intersected street. [policy,following VDOT practice] NA street grade is less than 4%for a minimum of 40'from the edge of pavement of the intersected street. (This grade can be within the first road curve which transitions from the 2%intersected cross grade)[policy,follows ord.for travelways 18-4.12] pipe and utility crossings shown and labeled cross drain locations shown and labeled with VDOT designations(CD-1,2)at every major cut and fill transition or sag curve VA the station of intersections are shown and labeled with the street names IVA grades are a maximum of 6%in turnarounds NA grades are a maximum of 4%through roundabouts atiko Street details containing:(applicable to road or street plans) .f typical sections for each street,street segment,or alley ✓ pavement widths meeting design standards IVO pavement crown at 1/4":1'slope V pavement surface,base,and sub-base thicknesses and materials W` curb andgutter where applicable with VDOT designation CG-6 and stone base of 6"21-A or better(CG-2 also acceptable if a gutter is not needed KA PP � ( ), P for drainage) S t 0 shoulder at 1":1'slope or flatter and 4'or greater width for rural sections ,�''A maximum slopes of 2:1 or flatter[policy] •* t'J proposed slopes steeper than 3:1 have low maintenance(not grass)ground cover specified on the plan[Policy] MO Albemarle County Engineering Final Plan Checklist Page 3 of 6 Na guardrail over all fill slopes and culverts,with 3'additional shoulder,using VDOT designations(GR-2,GR-2A,etc.) A right-of-way/easement width,centered on street,meeting design standards jh sidewalk location and widths,minimum 5'width,4"concrete surface,4"2I-A stone base,with underdrains(UD-4,etc)per VDOT standards where applicable itl planting strip if applicable,6'minimum width[14-422] ditches dimensioned at 3:1 slope from shoulder,1'depth min.,and 4'min.width from shoulder to ditch centerline,for rural sections Alli alleys have 12'pavement width,with 14'wide stone base[14-410] Ahfi transitioning detail(20'minimum)for roll-top curbing in front of any inlets NA Albemarle County general construction notes for streets )).r�inage profiles:(applicable to site plans,road and drainage plans) [14-311,18-32]drainage profiles for each pipe,structure or channel must contain: n}A existing ground N A proposed ground a any channel linings all utility crossings N A. a VDOT designation(MH-1,DI-3B,etc.)for each structure throat length for each drop inlet grate type for each grate inlet 1,4 a label on each structure to correspond with the computations material and strength class or gage of each pipe N manhole access every 300'for 15"-42"or 800'for 48"or greater N pipe slopes at 0.5%min.to 16%max.(per VDOT Ands for anchors over 16%) N concrete inlet shaping(IS-1)specified on any structure with a 4'or greater drop A safety slabs(SL-1)in any structure taller than 12'. ""' N A top or rim elevation for each structure ALA all invert elevations for each structure(with positive flow drop between inverts). NA end sections(ES-1)or endwalls(EW-1)on all pipe outlets. Endwalls for culverts 48"or taller ti A scour outlet protection at all outlets,corresponding to computations Dr nage computations:(applicable to any plan proposing pipes,channels,etc.)Pipe computations for all pipes All proposed systems are designed within open channel full flow capacities. tfk For systems within drainage easements,all proposed pipes are a minimum 15"in diameter There are no excessive outlet velocities(>15fps) NA County Engineer approval has been obtained for existing systems which may exceed open channel flow capacity Curb inlet computations for any curb inlets on grade M All spreads are less than10' carryover is accounted for NA 100%capture at entrances so no flow runs out entrances into travel lanes JA 100%capture or overland flow of capacity storm to stormwater management facilities Curb inlet computations for any curb inlets in sump conditions Ark All flow depths are below 6"in the capacity table Nti All spreads are less than 10' - w. NA 100%capture or overland flow of capacity storm to stormwater management facilities Ditch computations for any ditches ditch linings specified per plans meet velocity requirements CulvertwtRcomputations for any culverts ► headwaters<1.5 x culvert height,and 18"below shoulder elevation of streets. "" O�u1gt protection computations for all outlets dimensions and stone sizes for all outfalls Proposed pipe and inlet drainage area map ✓ limits of all areas and sub-areas draining to proposed structures,and existing structures or channels which will be impacted acreage of each drainage area as used in computations enlift ✓ hydrologic coefficient for each drainage area as used in the computations V time of concentration for each drainage area as used in the computations _kA destination structure labeled for each drainage area Stormwater management plan:(applicable to any plan containing stormwater management facilities)[17-303,304,and the Virginia Stormwater Management Handbook] Existing drainage area map: J existing conditions for site and off-site areas draining to proposed stormwater facilities(The stormwater management analysis should not include aim areas which do not drain to proposed facilities) • drainage divides for all drainage areas to proposed facilities as used in computations • acreage of each drainage area,labeled on the map area and matching comps ✓ coefficient used for each drainage area as used in comps ✓ time of concentration for each drainage area where applicable as used in comps ,... P nrnsed drainage area map: • proposed conditions for the site and any off-site areas draining to proposed stormwater facilities(The analysis should not include off-site areas which do not drain to proposed facilities) _V. drainage divides for total drainage areas(not sub-areas)to proposed facilities,matching the computations. Sub-areas may be shown on added exhibits or sheets. ..." acreage of each drainage area,labeled on the map matching comps coefficient for each drainage area,labeled on the map matching comps \/ time of concentration for each area labeled on the map where applicable,matching comps Aj fk for future development to be considered in the analysis,include assumed land uses,impervious areas,and hydrologic coefficients on the proposed a drainage map Albemarle County Engineering Final Plan Checklist Page 4 of 6 Pla"">;ew and details: 4.1011 stormwater facility and site layout as shown on the site or subdivision plan sheets,preferably at a scale of 1"=30'or 1"=20'. ✓ 90%or more of site development captured in facilities for water quality(ordinance requires as much as practicle,90%is a target) I Albemarle County general stormwater notes .1 facilities are not in the floodplain ✓ facilities are not in buffer areas .� facilities meet or exceed requirement removal rates J facilities are off-line of major streams • facilities are not built over any other utilities(sanitary sewer,water,gas,fiber optic,etc.) NA permanent stormwater management easement encompasses 100yr high water mark,all structures(embankments if present)and access r J flow is not short-circuited,flow path is 2:1 or greater in all water quality facilities,without the use of baffles or extended dikes Cross-section details of each facility including; AM embankments(between 3 and 25 ft in height) top width 8ft m .,10'for heights 15'to 20',12'for dams over 20',heights measured from the outside toe upstream face slope 2:1 or flatter,labeled downstream slope 3:1 or flatter,labeled A inl0yr and 100yr high water elevations labeled with 1 ft freeboard for 100yr storm with emergency spillway or 2 ft freeboard without emergency spillway Al an impervious core 4.. Al a cutoff trench of minimum 4'wide, 4'deep and 1:1 sloped sides • principle, spillway MA riser crest 1'below emergency spillway if present 1J riser crest stays within weir flow control during the 10yr storm trash racks over all inlets and controls to prevent clogging trash rack over riser crest is not flat(no DI-7's) h riser size and materials labeled f,1 barrel size,strength,material,inverts and slope labeled J all orifices,weirs or other control devices labeled with dimensions and inverts J" control orifices not more than 25%of riser perimeter at any point(does not affect riser structural integrity,25%is a target) OVA riser base size and dimensions labeled access to riser is provided(riser should be in dam,not free-standing) AM NArgency spillway dimensioned and labeled invert labeled NA dimensions in control section dimensions in channel section provided if different than control section .24 linings labeled and shown where applicable spillway over native soils,and/or sufficient armoring provided N Nent forebays provided for all retention basins,constructed wetlands,and basin biofilters at all inlets q sized to 0.25"of runoff per impervious acre(can be included in WQV) MA direct vehicle access provided biofilters with minimum floor dimensions labeled does not receive any stream base flows,and; areas of sheet flow into facilities are protected from erosion by appropriate scour protection stone or energy dissipation measure ✓ plants are shown and labeled with height or caliper 3 plant species are specified(3 trees if present,3 shrubs)with sizes ✓ biofilter floor is 2.5%of impervious cover for type I,or 4%of impervious cover for type II 2.5'depth of sand/soil media 1'-1.5'stone drain in geotech fabric under media,with 6"perforated PVC pipe to daylight 0.5'ponding depth provided in facility overflow provided J biofilter area is flat cleanouts are provided at the end of the underdrain pipe,and every 50' Nq u'S subdivisions,facilities are in open space where present. In subdivision with no open space,facilities are out of yards and away from residences. Facilities must not be a nuisance in design or location.[17-304F] overland relief is provided for any facility in case of clogging. The failure of any system will not cause structures or yards to flood[17-304F] Am Retention basins have appropriate water quality volume;3WQV for type I,4WQV for type II. good base flow,or 10 acres or more drain to the pond r=^ normal pool elevation is labeled on plans AIA 15%of surface area is a depth of 1.5'or less 4614 15%of surface area is a depth of 1.5'to 2' 70%of surface area is a depth of 2'to 6'(greater depths are counted in WQV) a 10'-15'vegetated strip/safety bench is provided around the perimeter for Type III,a 10-15'wide and 1-1.5'deep aquatic bench is provided typical 10'x10'planting area specified for aquatic bench VA at least 3 species of aquatic plant used MA extended detention basin II(enhanced)has marsh zones normal pool elevation is labeled on plans 20%pool areas 1.5'-4'deep 40%shallow marsh 0.5'-1.5'deep,contains 1 WQV 40%high marsh 0.5'deep or less .,d as-built data is provided for existing ponds and drainage structures and facilities existing ponds and drainage structures and facilities are brought up to current standards(the rest of this list) vehicle access roads provided to all facilities .j access graded to 10'width and less than 20%grade 1 minimum 10'wide permanent easement over access Ada Albemarle County Engineering Final Plan Checklist Page 5 of 6 MA gravel surface or better for grades over 10% AI underground facilities have adequate manhole access at upstream and downstream points. manufactured pre-fabricated water quality facilities have a written approval of the plan from the manufacturer. NA minimum pipe sizes into and out of the facility are 15"diameter for maintenance Stormwater management computations:(Applicable to any plan with regulated by the Water Protection Ordinance) f water quality removal rate computation summary for each facility ✓ detention computation summary for each facility V channel computations for erosion and capacity for emergency spillway channels N drawdown computations for any extended detention facilities wr Ntakriser floatation computations for risers which are not concrete,or are taller than 10' .l routing model and results for each detention facility hydrology for each facility used to generate inflow hydrographs including; si hydrologic land use coefficients(CN,C),areas and flow times .V for the modified rational method,the critical durations used for the peak basin volume events for 2yr,l0yr and 100yr storms f as closely as possible,the drainage areas represent the site development,and not off-site areas V computations are provided for composite coefficients V reasonable C values are used(0.25 for woodlands,0.3 for nasture nrnre-dev nry 0.35 for dev.yards,0.75 for gravel) 0.9 FOR 110E12 5 times of concentration are representative of watersheds. If the omission of small sheet flow areas yields a higher peak flow,the small sheet flow areas are not used. Sheet flow should not exceed 200'. rr� u� -� -"-" �^ times of concentration generally decrease with development TCS in(.rease...CbC les.3e: 1►41 V Ic t.i Olt+kU 5. NA areas over 50 acres make use of more than one hydrologic method to verify computation of peak flows Nil contour areas and elevations used for storage,matching the plans ./ a stage-storage(elevation vs.storage volume)table with water quality volume requirements computed for facilities with volume requirements the hydraulic dimensions and coefficients for each weir,orifice,culvert or other control structure used in the routing model,matching plans II A flow control is maintained by the riser when present,not the outlet barrel pipe .� detention storage and routings are over and above water quality volumes Mitigation Plan(per the Water Protection Ordinance) till existing conditions as shown on existing conditions sheets(can be to a smaller scale) proposed conditions as shown on the site or subdivision plan sheet A outlined and/or shaded areas of buffer disturbance,with acreages labeled,matching the disturbances shown on the erosion control plan. outlined and/or shaded areas of mitigation,with acreage labeled A for re-plantings,mitigation area is two times disturbed area NA f�channel restoration,1'of restored channel for every 100sf of disturbed buffer. A stations at every 50'min.with existing and proposed cross-sections provided for restoration AA planting plan for mitigation areas per Riparian Buffers Guidance Manual by CBLAD detail provided for typical spacing(i.e.20'x20'detail with placement). native plants used with species,size,root condition specified N14 maintenance maintenance narrative and schedule on plan,including a completion date. areas restored or replanted for mitigation must be protected in easements or by maintenance agreements. Alt all concentrated discharges treated or extended to adequate channels to preserve buffers. Erosion and Sediment Control Plan:(per the Water Protection Ordinance)[Items taken from Water Protection Ordinate,Article I,and the Virginia Erosion and Sediment Control Handbook,minimum standards and specifications] Narrative: ✓ narrative and project title ✓ project description i/ existing site conditions description ✓ adjacent areas description N19 off-site areas description including any off-site areas for borrow,waste or other disturbance. NA special use permit for cut greater than 50,000cy in RA zoning ✓ soils descriptions County erosion control notes stormwater runoff considerations:this can refer to the stormwater management plan sediment basin design computations summary for each sediment basin sediment trap design computation summary for each sediment trap Erosion and sediment control plan: limits of clearing and grading encompassing all disturbances,entrances,staging and parking areas,areas where sediment laden runoff will cross,or any construction related activities. This must match any landscaping and conservation plans a construction entrance(CE)draining to a sediment trap or basin t..."" dust control symbols(DC) 10/ temporary and permanent seeding symbols(TS,PS) {/ existing contours and topography _✓ existing drainage divides i✓ existing vegetation,with trees to be saved located by drip lines. This must match any landscaping and conservation plans protection provided for all stages of construction no erosion control measures in the way of construction access or grading(Diversion dikes or silt fence are not placed in the middle of the site,or through access or grading. Sediment traps are not under or on top of fill. Construction entrances are not on fill,etc.If the concept for site protection is not adequate in this regard,further review of the plan may not be possible) existing soil boundaries are shown with labels. Areas already disturbed are indicated,with constructed fill depth or cut noted. critical erosion areas are identified;areas of constructed slopes,areas near property lines t) adjacent off-site disturbances are shown with erosion control facilities // a stockpile location f a staging and parking area,or other construction related areas Albemarle County Engineering Final Plan Checklist Page 6 of 6 ✓ diversion dikes are used to direct drainage to traps and basins silt fence is not used across contours in place of diversion dikes. 1.." silt fence is limited to areas of sheet flow with'/4 acre per 100f1 of level on-grade silt fence 0. temporary slope drains(TSD)or diversions are provided to prevent discharge over disturbed or fill slopes inlet protection(IP)on all inlets culvert inlet protection(CIP)on all culvert inlets N& outlet protection(OP)on all outlets all watercourses are protected and encroachments minimized stream crossing(USC,SC)and diversions are provided at all stream crossings. V final contours are shown per the site or subdivision plan sheets ✓ WPO stream buffers shown and protected undisturbed. Disturbances require WPO Program Authority approval and a mitigation plan. OVA- Zoning Ordinance buffers shown and protected undisturbed. Disturbances require Planning Commission approval of a waiver. Floodplain shown and protected undisturbed. Disturbances require a Special Use Permit. V final contour shapes and slopes ensure no undrained pockets or stagnant pools . adequate channels(MS-19)provided for each outfall ®` V all swales and low points at the perimeter of the site have a sediment trap or basin(If the concept for site protection is not adequate in this regard, further review of the plan may not be possible) all traps and basins are shown with proposed contours For each trap; ,�. ✓ drainage area is 3 acres or less �/ sized for total drainage area,including those for in-line upstream facilities wet storage is 67cy or more too dry storage is 67cy or more toe* wet storage is 4'deep or less ✓ wet storage side slope is 1:1 or flatter 1'' dry storage side slope is 2:1 or flatter stone weir is 611 per acre of drainage area i/ embankment and stone weir height is 5'maximum from outside toe t/ embankment top width is adequate(see table 16 reference) .46 2:1 length:width ratio for flow path For/neach basin; ��J4 sized for total drainage area,including those for in-line upstream facilities MA wet storage is 67cy or more �,. NA dry storage is 67yr or more VA wet storage side slope is 1:1 or flatter iy4 dry storage side slope is 2:1 or flatter �tJ� embankment 15'high or less from downstream toe principle and emergency spillways sized per handbook requirements SVA embankment has I'freeboard during 25yr storm with emergency spillway A/AA embankment has 2'freeboard during 25yr storm without emergency spillway trash rack/anti-vortex device specified per handbook requirements NA riser anchor size specified per floatation computation dewatering device sized for 6+hr drawdown of dry storage:3"dia.minimum Al safety fence and signs stating"danger,quick sand,do not enter"provided if near any residential properties,or public access /1!� structures and embankment match permanent design for facilities to be converted to permanent stormwater management facilities /Vj embankment top width is adequate(see reference details) n//} 2:1 length:width ratio for flow path. If necessary,baffles specified only on temporary structures Details: AM a paved construction entrance detail(see reference details)for projects in the development areas over 10 acres 1/ a typical section for each temporary channel or diversion,referenced from the plan sheets. Existing ground should be shown at the maximum cross- slope on the plan. N4 details and copies of Program Authority permissions for any variances. Misc: /q mass grading(also called rough or early grading plans which contain only approximate finished grades and culverts necessary to grade.)can only be permitted within planned developments where a concept grading plan was approved with the rezoning. The agent(Director of Planning)needs to formally determine that the grading plan is in general conformity with the approved rezoning plan. Otherwise,all final plans need to be approved 4.40 prior to issuance of grading permits. a APPENDIX"8" COUNTY APPLICATIONS CHO CHARLOTTESVILLE ALBEMARLE AIR-1POR T 100 BOWEN LOOP,SUITE 200 CHARLOTTESVILLE,VA 22911 4.0 Ph 434.973.8342 October 21,2009 Fx 434 974.7476 Mr. William D.Fritz,AICP County of Albemarle Department of Community Development 71 401 McIntire Road Charlottesville,Virginia 22902 RE: Minor Site Plan Amendment Construct Runway 3 Offset Localizer/DME Charlottesville-Albemarle Airport Charlottesville,Virginia Non-AIP Delta Project No. VA 08107 Dear Mr.Fritz: Please find enclosed eight(8) folded copies of the plans for the above referenced project, one(1) signed Application for the Minor Site Plan Amendment, and a check,Check No. 13508, in the amount of ninety- five($95.00)dollars for the application fee. Please be advised that a separate submittal has been filed with Ms. Amy Pflaum of the Albemarle County Department of Community Development for the Erosion and Sediment Control and Stormwater Management Plan. — If you should have any questions regarding this matter,please do not hesitate to contact our office. Sincerely, - 2?)—( ja(A42' 1/"11,S,..---- Barbara W. Hutchinson,C.M. Executive Director bwh: .11111 cc: Amy Pflaum,County of Albemarle w/o end. Sue Winslow,P.E.,Delta w/o end. Application for Major & Minor Site Plan Amendments and All Reinstatements of Denied or Deferred Site Plans ❑Major Amendment(Subject to Planning Commission Review)...$270 Minor Amendment(alterations to parking,circulation, 17 folded copies of pion are required building size,location)...$95 d folded copies a6sketch plan arc required ❑Reinstate Plan Review After 10 day Denial-5200 []Reinstate Plan After Site Review Denial or Suspension=565 ❑Reinstate Plan Deferred by Applicant Q To a specific date=$35 Q Indefinitely=$75 17 folded copies of plan are required Groundwater Assessment (Required for all non-residential site plans not serviced by public water) Was a Groundwater Assessment conducted for the existing site plan? ❑YES 0N If NO and the new plans show a use less than 2,000 gallons per day 0 Tier 3 Groundwater Review=$400 If NO and the new plans show a use greater than 2,000 gallons per day 0 Tier 4 Groundwater Review—$1,000 If YES and the use goes from less than to more than 2.000 gallons per day 0 Tier 4—Tier 3-$400 If YES and the use does not change from less than to more than 2,000 gallons per day 0 No fee 0 Relief from conditions of approval from Planning Commission or landscape waiver by agent-$180 0 Extension of approval prior to expiration of an approved plana$45 ❑Rehearing of Site Development Plan by the Planning Commission or Board of Supervisors-$190 ❑Appeal of Sits Development Plan to the Board of Sopervlsors-$240 Project name: Construct Runway 3 'tisaporary Offset IaCalizer/LMB Tax map and parcel: 32-10 Magisterial District Whitehall Zoning: Rtrrfrl Anzac Physical Street Address(if assigned): 100 Baldest Loop, Suite Location of property(landmarks,intersections,or other): West of Bowen Lxp, North of interctirn of S.R. 743 and S.R. 606. • Contact Person(Who should titin cellhvrite concerning this project?): &OM WinSIOW• P.E. — I1?1ta Airport Cartatil tants, Iix. Address 9]. ftlar Gaut 4rira 1CO City Pirjstrr,4 State VA Zip 91746 Daytime Phone(&n+) 275-6331 Fax#(804) 275,8371 E.maii swinslodadeltaadrptrt.can Owner of Record (harlottesvi31e-Albalar].e Airport Authority Address 100 Bowen Imp, Suite 230 City Charlottesville State VA Zip 22911 Daytime Phone( 434 973-8342 Fax H(434) 974-7476 E-mail Applicant(Who is the Contact person representing?): Barbara Hutchinson, C.M. Address 1t0 Bcrysen Loop, Suit 2C0 City Charlottesville State VA zip 22911 Daytime Phone( 434 973-6342 Fax#(434) 974-7476 E-mail linttrhirKxnti,rhn.rsan FOR OFFICE USE ONLY SDP# Fee Amount S Date Paid By who?__ Receipt H_ Ck% By: County of Albemarle Department of Community Development 401 McIntire Road Charlottesville,VA 22902 Voice: (434)296-5832 Fax: (434)972-4126 llll1 Y?Page1oft Intended use or Justification for request: An earth platform is required to be constructed to install a temporary oftset. lora 1 i zer ent u a. MIR Frpri Twiti =tired in ren or ti nal Instipfileftt San (ES) Ourirst ccitattctian ctf the f lC)' R►uwav ext tin. This will permit aircraft to safely oerate during Periods of systen yiaiMlity. Owner/Applicant Must Read and Sign This site plan as submitted contains all of the information required by Section 32.5(Preliminary Plan)or Section 32.6(Final Plan)of the Albemarle County Zoning Ordinance. I understand that plans which lack information required by said sections shall be deemed incomplete and shall be denied by the agent within ten(10)days of submittal as provided in Section 32.4.2.1 or Section 32.4.3.3 as the case may be. For Final Plans Only:To the best of my knowledge,I have complied with Section 32.4.3.1 and obtained tentative approvals for all applicable conditions from the appropriate agencies. AldiPA Ji/ �--- I-2)-d9 of Owner,Con t Purchaser,Agent Date Barbera Hutch:hem C.M. 434-973-8342 Print Name Daytime phone number of Signatory t 11119,07 Tap 2 oft ap iva uo•pwa a 4+ s c co 0 0 L 401.0 CI) * Ln r-1 00 0,1o 0 th N N 0 .- • o NMIC) MI i Z N 0 111 CD 1. O ii'�h� 01 O `yam' i. VIM ru 07, 04 to pON , R, W o 0p CC IMO ti) iiiiiial -n a W N N n, m INN al o 0 o 0 0 V o 0 0 0 to l o o a to •r F- 61 to U 0) O M N N W urIO Q J o CC 0 i al F— iiiii o Ln 0 CC 4 rn W z ..:7; a) N • CC cv m FeCL DgN a� 0 • N a J G `` �, = E i Z tom-na t0 1,4 > EC .W.1 .Q 0 po ui Lnw , JQ �z� Q A W MI o OCC w H cu V < i �a � - § a) aCO - al o ani o W I V.Z U A U W H CZ O Z a a v § I Q- V a CHO CHARLOTTESVILLE ALBEMARLE AIR PORT 100 BOWEN LOOP.SUITE 200 CHARLOTTESVILLE,VA 22911 Ph 434.973.8342 Fx 434.974.7476 October 21,2009 Ms.Amy Pflaum County of Albemarle Department of Community Development 401 McIntire Rd.,Suite 211 Charlottesville,VA 22902-4596 RE: E&SC and SWM/BMP Plan Construct Runway 3 Offset Localizer/DME Charlottesville-Albemarle Airport Charlottesville,Virginia Non-AIP Delta Project No. VA 08107 Dear Ms.Pflaum: Please find enclosed two (2)folded copies of the plans for the above referenced project, one (1) signed Application for Review of Erosion and Sediment Control Plan and Stormwater Mangement/BMP Plan, and a check,Check No. 13509, in the amount of six hundred($600.00)dollars for the application fee. Please be advised that a separate submittal has been filed with Mr. Bill Fritz of the Albemarle County Department of Community Development for the Minor Site Plan Amendment. If you should have any questions regarding this matter,please do not hesitate to contact our office. Sincerely, kArif"td)-' )41-1164 Barbara Hutchinson,C.M. Executive Director bwh: cc: Amy Pflaum,County of Albemarle w/o encl. Sue Winslow,P.E.,Delta w/o encl. Application for Review of { Erosion & Sediment Control Plan & Stormwater 44 1= v. Management/BMP Plan & Stream Buffer Mitigation Plan 03 Erosion&Sediment Control Plan ®Stormwater Manegetnent/BMP Plan 0 Stream Buffer Mitigation Plan 0 E&S Plan Amendment 0 SWM Plan Amendment (Previous Plan N ) (Previous Plan# ) O E&S Plan with Variance 0 Request for Exception N of Variances 0 SWM Plan Resubmittal []E&S Plan Resubmittal WPO Applies tion N WPO Application# Submit 2 copies each of applicable plans/narrative/computations Project Names Construct Rummy 3 Temporary Offset Locallzer/DE Tax map and parcel: 32-10 Zoning; Rural Areas Amount of Land Disturbance: 3.0 Acres Location of property(tandmari<'s,intersections,or other) W9St of Bo74031 LooP► North of intersection of S.R. 743 _ Sssl S.R. ttrtx Contact Person(Who should Wv call/write concerning this project?): Barbera Hutchinson, C.M. ' Address 100 Bowen.Loop, Shite 2C) city Qa3rltattenirtlle State VA Zip 22911 Daytime Phone(434) 97343342 Fax 1(434) 974-7476 P-malt .c a m Owner of Record CRterlat 1e Airi 34)AuAuthDrlty Address 201 Bowen Loop — city Qiar]nttasville stats VA zip 22911 Daytime Mono(434) 973-8342 Pax 1(434) 974-7476 E-mail hhtitr it 1y.txom Contractor Austin Electrical ft.d41 S.rw•.1 ,. __.. Address P. 0. Boa 396, 17566 Main Street City Buchanan State VA zip 24056 Daytime Phone(540) 25tr-1065 Fax 1(540) 254-2729 E-mail austfnellalrer izcn.net Plan Preparer Susan Winslow, P.E. - Delta Airport Consultants, Inc. I i Address 9711 Farrar taut. Suite 100 City RidIDDLII State VA zip 232% Daytime Phony(0+) 275-8301 Fax a(8(34) 275-8371 E-mail swinalottkieltsairrort.com "" Owner/Applicant Must Read and Sign By signing this application as owner,I hereby certify that ail requirements of the approved Erosion Control Plan,Stormweter MaaagemeoUSMP Plan,and/or Mitigation Plan will be compiled with and I have the authority to authorize the land disturbing activities and i dcv 1.meat on the subject property. I hereby grant the County of Albemarle the right to cater upon the property as required to ensure ' corn I once ith the appro-d pie S g : re of Owner,Contact Purchaser Date Berbera Hutchinson, C.M. 434 973-8342 Print Name Daytime phone number of Signatory FOR OFFICE USE ONLY WPO N I Re Fee Anent$ Date Paid ay who? Receipts Oct By: r . Revised Sepeeor6er t S,20316 Page I of 3 I EROSION CONTROL PLAN: (SUBMIT 2 COPIES) Land disturbing activity pertaining to single family dwelling unit: 1. Plan Review $150 per review (TO BE PAID AT TIME OF APPLICATION AND EACH SUBMITTAL THEREAFTER UNTIL APPROVAL) 2 Permit and First Year Inspection Fees $150 (TO BE PAID PRIOR TO SCHEDULING PRECONSTRUCTION CONFERENCE FOR EROSION CONTROL PERMIT) 3. Annual Permit Renewal and Inspection Fees $150 (TO BE PAID ANNUALLY,STARTING WITH SECOND YEAR,UNTIL COMPLETION OF APPROVED PLAN REQUIREMENTS) 4. Each reinspection $150 (REINSPECTION FEES ARE INVOICED TO THE LANDOWNER) Land disturbing activity pertaining to non-exempt agricultural land: 5. Plan Review $150 per review (TO BE PAID AT TIME OF APPLICATION AND EACH SUBMITTAL THEREAFTER UNTIL APPROVAL) 6. Permit and First Year Inspection Fees $150 (TO BE PAID PRIOR TO SCHEDULING PRECONSTRUCTION CONFERENCE FOR EROSION CONTROL PERMIT) 7. Annual Permit Renewal and Inspection Fees $150 (TO BE PAID ANNUALLY,STARTING WITH SECOND YEAR,UNTIL COMPLETION OF APPROVED PLAN REQUIREMENTS) 8. Each reinspection $150 (REINSPECTION FEES ARE INVOICED TO THE LANDOWNER) Alt other land disturbing activity: 9. Plan Review,Disturbed Area Less Than One Acre $150 per review (TO BE PAID AT TIME OP APPLICATION AND EACH SUBMITTAL THEREAFTER UNTIL APPROVAL) 10. Permit and First Year Inspection Fees,Disturbed Area Less Than One Acre $200 (r0 BE PAID PRIOR TO SCHEDULING PRECONSTRUCTION CONFERENCE FOR EROSION CONTROL PERMIT) II. Annual Permit Renewal and Inspection Fees,Disturbed Area Less Than One Acre $200 (TO BE PAID ANNUALLY,STARTING WITH SECOND YEAR,UNTIL COMPLETION OF APPROVED PLAN REQUIREMENTS) =01 12. Plan Review,Disturbed Area One Acre or Larger $300 per review (TO BE PAID AT TIME OP APPLICATION AND EACH SUBMITTAL THEREAFTER UNTIL APPROVAL) 13. Permit and First Year Inspection Fees,Disturbed Area One Acre or Larger $100(per disturbed acre (TO BE PAID PRIOR TO SCHEDULING PRECONSTRUCTION CONFERENCE FOR EROSION CONTROL PERMIT) 14. Annual Permit Renewal and Inspection Fees,Disturbed Area One Acre or Larger $100/per disturbed acre (TO BE PAID ANNUALLY,STARTING WITH SECOND YEAR,UNTIL COMPLETION OF APPROVED PLAN REQUIREMENTS) 15. Each reinspection $250 (REINSPECTION FEES ARE INVOICED TO THE LANDOWNER) 16. Amendment to Approved Plan S180/per plan review (TO BE PAID AT TIME OP APPLICATION AND EACH SUBMITTAL THEREAFTER UNTIL APPROVAL) 17. Variances $760/per request (TO BE PAID AT TIME OP APPLICATION) 18. SUBTOTAL EROSION CONTROL PLAN........................................» $ 300.00 Revised Sepbmber 1%2008 Pogo 2 of 3 STORMWATER MANAGEMENT/BMP PLAN&MITIGATION PLAN: (SUBMIT 2 COPIES) XXXXX 19. Stormwater Management/RMP Plan... $300/per plan review (TO BE PAID AT TIME OF APPLICATION AND EACH SUBMITTAL THEREAFTER UNTIL APPROVAL) 20, MTor Amendment of Plan $180/per plan review (TO BE PAID AT TIME OF APPLICATION AND EACH SUBMITTAL THEREAFTER UNTIL APPROVAL) 21. Request for exception ... $240 (TO BB PAID AT TIME OF APPLICATION) 22.Request for development in a stream buffer or for reduction or modification of stream buffer and mitigation plan(if not part of another document)—Single family dwelling unit or accessory structure $85 (TO BE PAID AT TIME OF APPLICATION) 23.Bach inspection or reinspection.... $60 (INSPECTIONFREINSPECTK)N FEES ARE INVOICED TO THE LANDOWNER) 24. Mitigation Plan $860 (TO BE PAID AT TIME OF APPLICATION) 25,SUBTOTAL SWM/BMP PLAN S 1(1) TOTAL APPLICATION FEE: (Add lines 1$and 25)... $ fin in THE OWNER SHALL BE RESPONSIBLE FOR ALL REINSPECTION AND/OR ANNUAL RENEWAL FEES WHICH MAY BE CHARGED TO THIS PROJECT. Rev/11A September 15,MS Pep 3 or 3 Q) '�Pe9 w A S C {J) �'iiO 0 C:) Ln ') 0 • M r-fQ O O 0 o 0 lf) o 0 U} o ,n o. ` yr, CS 5 Y O' 11 11 er el C:1. ,• i` 00 O .10 CD ,y, Ccm g o a.1 2ov W cv 3 a r� -.. • Csi Ig CV .... 0 { ru o r <Y cD CC O G1. o w v J v `� yr ru 'Q in a <. c!1 F o O b I O O 0+ O O o o o Ln O u rn O 0 O p 0 = l a) lD E— 0 a U rn O Zto J o ,a O Q a CC 1 LEI 11..• Q Ti o 0 O 2 ..4 a. a COcc CC DgN Cf) N tr N E cm LL Q Nye r--1 (u -a r7 .r:1 O „ J Q O-'J f� Q W r-11 r n 2 o r1 Q z> r-1 0 N -H .. W4.4 W IX W vOm 0 +-) -H i a t� ¢g H Ids U w �a v~c.) N r I Y. J z o X � a.� MI (4 o -H 0 W 04 C3 c3 O 'CrU F W CI N w o z C si WOO MI .40 444 APPENDIX"9" COUNTY BACKUP DATA FOR PROJECT SITE County of Albemarle - GIS-Web -Property Information Page 1 of 2 Parcel ID: 03200-00-00-01000 Summary Information Parcel Information Total Acres 558.4830 Primary Prop. 4000 DICKERSON RD Address Other Address N/A Property Card(s) 10 Lot N/A Property Name CH'VILLE/ALBEMARLE AIRPORT Subdivision N/A Notes CHARLOTTESVILLE/ALBEMARLE AIRPORT 08/27/2008 DB 3640 PG 191 (CERTIFICATE OF PLAT) 555.906 - .003 AC DEDICATED TO VDOT + .002 AC ABANDONED FR VDOT + 2.578 AC ABANDONED FR VDOT = 558.483 AC PER PB 3640 PG 194. 12/06/2007 QUITCLAIM DEED PER DB 3524 PG 615 555.711 + .195 AC FR COMMONWEALTH OF VIRGINIA =555.906 05/08/2007 DEED OF DEDICATION PER DB 3414 PG 523 555.992 - 2.640 AC DEDICATED TO VDOT + 2.359 AC ABANDONED BY VDOT =555.711 PER PB 3240 PG 225 07/20/2006 DB 3254 PG 169 (CERTIFICATE OF PLAT) PORTION OF SR 649 RIGHT-OF- WAY TO BE ABANDONED AND ADDED TO TM 32-10 PER PB 3254 PG 171. 06/29/2006 DB 3240 PG 223 (CERTIFICATE OF PLAT) RIGHT-OF-WAY TO BE DEDICATED FOR RELOCATED SR 606 AND EXISTING RIGHT-OF-WAY TO BE ABANDONED PER DB 3240 PG 225. 05/23/2006 PER DB 3215 PG 206 555.647 + .345 AC FR TM 32-57A = 555.992 PER PB 3215 PG 210. 06/05/2003 HIGHWAY TAKE PER DB 2478 PG 417 557.852 - 2.205 TO VDOT .�„ =555.647 01/08/2003 QUITCLAIM DEED PER DB 2353 PG 643 553.743 + 4.109 AC FR VDOT =557.852 09/03/2002 DB 2263 PG 032 (DEED OF DEDICATION) 07/15/2002 DB 2229 PG 729 (CERTIFICATE OF PLAT) 557.813 - 4.070 AC TO VDOT = 553.743 AC PER PB 2229 731 08/07/2000 557.724 + .001 AC FR TM 32-17B + .005 AC FR TM 32-9C + .083 AC FR RIGHT OF WAY =557.813 PER PB 1944 PG 545 http://gisweb.albemarle.org/PropertyInfo.aspx?pin=03200000001000 10/15/2009 County of Albemarle - GIS-Web - Property Information Page 2 of 2 a Owner Information Owner CHARLOTTESVILLE-ALBEMARLE AIRPORT AUTHORITY Address 201 BOWEN LOOP CHARLOTTESVILLE VA, 22911 Owner as of Jan CHARLOTTESVILLE-ALBEMARLE AIRPORT 1st Most Recent Assessment Information Year 2009 Assessment Date 04/01/2009 Assessment Division of Property Reason Land Value $22,390,300 Land Use Value $0 Improvements $71,397,000 Value Total Value $93,787,300 Most Recent Sales History Previous Owner CHARLOTTESVILLE-ALBEMARLE AIRPORT AUTHORITY Owner CHARLOTTESVILLE- ALBEMARLE AIRPORT Sale Date 12/06/2007 Sale Price $0 Deed Book/Page 3524/615 Validity of Sale Invalid Sale Other Tax Information as of Jan 1st State Code Local Government Tax Type Exempt Parcel Level Use Passenger Terminal Code Primary Zoning Rural Areas Designation Appraiser RHW a a http://gisweb.albemarle.org/Propertylnfo.aspx?pin=03200000001000 10/15/2009 County of Albemarle- GIS-Web -Property Information Page 1 of 2 Parcel ID: 03200-00-00-01000 Other Parcel Characteristics School Districts (Unofficial) Elementary School District Hollymead Middle School District Sutherland High School District Albemarle Magisterial District &Voting Precinct Information Magisterial District Whitehall Voting Precint Earlysville Census Information Census Block Group 1 Census Tract 102 Historical and World Heritage Information 4481. Virginia Landmark Register? No National Historic Landmark? No National Register of Historic Places? No World Heritage Site? No Zoning Information Primary Rural Areas Secondary Unassigned Minor Unassigned Other Unassigned Proffered? Yes Natural Resource Extraction Overlay? No Flood Hazard Overlay? No Airport Impact Area? Yes Scenic Stream Overlay? No Entrance Corridor? Yes Comprehensive Plan Information Comp Plan Area Hollymead Community Comp Plan Land Use - Primary Institutional Comp Plan Land Use -Secondary Industrial Service Comp Plan Land Use - Minor Unassigned Comp Plan Land Use - Other Unassigned a a http://gisweb.albemarle.org/PropertyInfo.aspx?pin=03200000001000 10/15/2009 County of Albemarle - GIS-Web -Property Information Page 2 of 2 Land Use Survey Information Land Use - Primary Public Number of Structures - Primary 0 Number of Dwelling Units - Primary 0 Land Use - Secondary Open Number of Structures - Secondary 0 .14 Number of Dwelling Units -Secondary 0 Land Use - Minor Unassigned Aft Number of Structures - Minor 0 Number of Dwelling Units - Minor 0 Other Information Subdivision N/A MPO/CHART Area? Yes Traffic Analysis Zone (TAZ) 097 Jurisdictional Area Designation Water&Sewer Watershed Chris Greene Lake Water Supply Protection Area? Yes Development Area? Yes Other Rural Land? No Ag/Forest District N/A -4110 Conservation Easement? No ddif 410 KI. http://gisweb.albemarle.org/PropertyInfo.aspx?pin=03200000001000 10/15/2009 019 020 021 .4 • v 14_ 9 ;r0-194 4.' 111 e^' •pr`fa, MO 14.1111, 111;, --"4 *20-19 jill'U - ._-, LP '806 �� L AU57IN \ I] X 85901 C/ f :�/O L-,1 CR ��1 - -.SPO �..'•� Oot RUN 040 32-2 3P . , �'--- % 32G 040 // CHRIS GREENE LAK N _ il ( _ , 4 i , ,c, 9, /„, , ,, , ,r, .... .,.. „,,,,,, 32-8 r--- ��/ , -, ®/a .3 - , , `�,� ,,,,, 4,...., aw,,-„,%, ii:441.„ta•:t. A.,„),_., %<) ,,\ LRS RIDGE m �- r�•i!®j O\/� 7,,' • F,,Itkriti•pki,-,1 dtT,RD q. J OF/ 19j •2K, J'r' ..cerr;,. e"e �'" w ® •o/SC•O EV--DR - 44101:111/ *32-10 � 31C 32-100 �. 9P. 32-10E a: II) 32-10F �� �/ 9e9�,0) 19D ` ® ?2!Y 32,10G / (/�� CH W 32-10fO Cr,2/ anmo ;. 32-10P sos Co�gC .\ .p�'rg4' \�\o 22 4 V R 32-105 ic7A: 32-10X \i", '1 h2�®� '32-10Y ® ' • F �% 32' 1 RE RHSIDE OR- j � F • Ac O 32-10 B S�� 'F 22 N� / 6 r/ � �� 3z-1 occ ���' cv eV) o 32-10DD �4 1� ^3r/: � ter 32-10EE °ii---- �, • N� ,0 32-1001-1014 /V ,P 32-2001-2014 17E3 r, / A. (fct - RIM Iii! ' tit ._ 'tot �ir 4:: L1� JI P. • 10:iff ry a� .., :41\7. RWooD z A2 tIP' • O RD �� / 'q r fh 4. / qyA a 32iii131 40 r,. !/ u% ;_. tp, ® ,,, ---/ 030 CRESTFIBC` I. w E <. Or °kp• %,---5,41*• A7 u ®Q' 2' `¢-�3 rr CpJ ;� n'� O, ' a� O /�ryEIP rNERIDCE I.T1'' 42 % �' `��/ cOF3�9 32D o =o� 0 , 4684 of co �� off,. n if I ak,„,„ A<0 R txal Part�1 i 7 u° ' ... ii-qpred4P0p• V v •4 , CC' 4664 Part 2 Qv 5• \� WD /J32-4_44.4.•/ 2C °� s D o°eK + ® �.. 401 ��eR 46134 Mlifft'>_ r 4' 1 •- 46-5 1! Aa i m - 045 046 047 TaAlbemarle CountyMap: Scale 03 032 .011 °'- ".e Feet `4 � ��. Note:This map is for display purposes only 11.1(69' and shows parcels as of 12/31/2008. ,,..n. See Map Book Introduction for additional details. a Susan E. Winslow From: James D. Nixon, Jr. - Sent: Wednesday, June 03, 2009 4:44 PM To: Susan E. Winslow;William M. Eschenfelder Subject: FW: SWM Maintenance Agreement for RW 21 Extension, Phase IA @ CHO - James D.Nixon,Jr.,P.E. Delta Airport Consultants,Inc. 9711 Farrar Court,Suite 100 Richmond, Virginia 23236 Phone: (804)275-8301 Fax: (804)275-8371 e-mail:jnixon@deltaairport.com VIM From: Pam Shifflett [mailto:PSHIFFL@albemarle.org] Sent: Wednesday, June 03, 2009 4:23 PM To: James D. Nixon, Jr. Cc: Philip Custer; Ana Kilmer S-bject: RE: SWM Maintenance Agreement for RW 21 Extension, Phase IA @ CHO Mr. Dixon: I received the Stormwater Agreement this afternoon. Page one of the agreement shows the Deed Book/Page as 818/210. The County real estate records show DB/page 3524/615 (this is the DB/page we used on the SW Agreement for the airfield lighting vault project). Page one also shows the"site plan/subdivision plan known as WPO-2008-00059". There should be a property/project description in this"blank" on the agreement rather than a number. I would suggest using "Charlottesville-Albemarle Airport"— I believe we may be able to then use this agreement for future airport pr jects - that may require SW agreements. I will be out of the office until Tuesday, June 9. Ana Kilmer will be providing backup for me during my absence. If you could correct page one and have Ms. Hutchinson e-mail that page to Ana Kilmer(I've copied her on this e-mail so you have her e-mail address) requesting that she replace the page one we received with the revised page one we should be able to start processing the agreement. Of course, you can just submit another fully executed agreement if you prefer. Ana: I've left the agreement/check I received under the keyboard on your desk. Thanks Pam Shifflett County of Albemarle Department of Community Development - 434-296-5832, ext. 3246 - From: Philip Custer Sent:Tuesday, June 02, 2009 11:02 AM To: 'James D. Nixon, Jr.' Cc: Pam Shifflett Subject: RE: SWM Maintenance Agreement for RW 21 Extension, Phase IA @ CHO 1 I have not seen the agreement come through either. Also, have you contacted the planner to process the site plan approval? A grading permit cannot be issued until the site plan us signed. I will review the documents attached to Bill's email this afternoon. I don't expect to have any issues with them. From: Pam Shifflett Sent: Tuesday,June 02, 2009 10:40 AM To: 'James D. Nixon, Jr.' Cc: Philip Custer Subject: RE: SWM Maintenance Agreement for RW 21 Extension, Phase IA @ CHO I have not received the SWM agreement to process for approval. I also have not received the Water Protection Bond to process for approval. Pam From: James D. Nixon, Jr. [mailto:JNixon@deltaairport.com] Sent: Tuesday, June 02, 2009 10:38 AM To: Pam Shifflett; Philip Custer Cc: Susan E. Winslow; William M. Eschenfelder Subject: SWM Maintenance Agreement for RW 21 Extension, Phase IA @ CHO Pam and/or Phil: Have you received the SWM agreement from Barbara Hutchinson yet? Faulconer is scheduling the E&SC Preconstruction meeting with Ray lily later this week,and wants to start construction the first of next week. Thank you, Jim James D.Nixon,Jr.,P.E. Delta Airport Consultants,Inc. 9711 Farrar Court,Suite 100 Richmond, Virginia 23236 Phone: (804)275-8301 Fax: (804)275-8371 e-mail:jnixon@deltaairport.com 2