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Home My WebLink AboutWPO201500042 Review Comments WPO VSMP 2015-11-02�pF A COUNTY OF ALBEMARLE Department of Community Development 401 McIntire Road, Room 227 Charlottesville, Virginia 22902 -4596 Phone (434) 296 -5832 Fax (434) 972 -4126 VSMP Permit plan (Amendment) review Project: Old Trail Village Block 27 —WPO Amendment Plan preparer: Chris Mulligan, Bill Ledbetter, Raleigh Davis — Roudabush, Gale & Assoc, Inc 914 Monticello Road, Charlottesville, VA 22902, cmulligan(a),roudabush.com, bledbetter(c)roudabush.com, rdavis (a)roudabush.com Owner or rep.: March Mountain Properties LLC [1005 Heathercroft Circle, Suite 100] Dave Brockman, dave(aoldtrailvilla eg com Plan received date: 6 Jul 2015 (Rev. 1) 1 Oct 2015 Date of comments: 28 Jul 2015 (Rev. 1) 2 Nov 2015 Reviewer: John Anderson A. Stormwater Pollution Prevention Plan (SWPPP) The SWPPP content requirements can be found in County Code section 17 -405. A SWPPP must contain (1) a PPP, (2) an ESCP, (3) a SWMP, and (4) any TMDL measures necessary. 1. Registration Statement submitted with block 27 is identical with the registration statement submitted to DEQ last spring (7 -May 2014). It is not immediately clear whether a registration statement is required, since this block is covered under VAR100043. Reviewer has left message with DEQ to advise on question of registration statement requirements for this (and future) block/s. In any case, please leave registration item #2 blank. (Rev. 1) Addressed. 2. Once WP0201400042 is approved, update SWPPP to include Approved block 27 ESCP and SWMP. (Rev. 1) Addressed. 3. TMDL: Update SWPPP to reflect DEQ, p. -1, 15- Aug -14 VPDES CGP coverage letter (VAR100043): DEQ staff has determined that the proposed land- disturbing activity will discharge to a surface water identified as impaired or for which a TMDL wasteload allocation has been established and approved prior to the term of the general permit for (i) sediment or a sediment- related parameter or (ii) nutrients. Therefore, the following general permit (Part 1.B.4) and SWPPP requirements (Part II.A.5) must be implemented for the land- disturbing activity, • Permanent or temporary soil stabilization shall be applied to denuded areas within seven (7) days after final grade is reached on any portion of the site; • Nutrients (e.g., fertilizers) shall be applied in accordance with manufacturer's recommendations or an approved nutrient management plan and shall not be applied during rainfall events; • Inspections shall be conducted at a frequency of (i) at least once every four (4) business days or (ii) at least once every (5) business days and no later than 48 hours following a measurable storm event. In the event that a measurable storm event occurs when there are more than 48 hours between business days, the inspection shall be conducted on the next business day; and • Representative inspections used by utility line installation, pipeline construction, or other similar linear construction activities shall inspect all outfalls. (Rev. 1) Addressed. 4. Alb. County recommends Applicant /Permittee periodically review and update VAR100043 SWPPP. (Rev. 1) Acknowledged. Engineering Review Comments Page 2 of 6 B. VSMP: SWPPP: Stormwater Management Plan (WPO201500042) — AMENDMENT To WPO201400004 VSMP Regulation 9VAC25- 870 -108 requires the VSMP authority to approve or disapprove a SWMP. This plan is disapproved. The stormwater management plan content requirements can be found in County Code section 17 -403. 1. WPO201400004 indicates water quality/quantity compliance —TITLE SHEET statement to this effect may be helpful. (Rev. 1) Addressed. 2. Review ISP comments, SDP201500015, 20 -May 2015, items 8, 9, 12, 13, 15, 17, 21. Revise accordingly. Also, RP comments, item #4 (SUB201500123). (Rev. 1) Addressed. 3. RP comment #4: Critical: Sheets 4, 6, 9 (Utility plan, Grading plan, Storm profile: Ex. 4144 4230 (outfall)) reflect a post - construction stabilized condition by proposing removal of Ex. Sediment basin. This is problematic. There is possibility future development of blocks 7, 6, 26, or 35 will require trap/basin in similar location (sheets 3, 9, 10). Construction of structures between inlet #223 and UBP (outfall) is contingent upon complete upslope stabilization of all areas/blocks draining to Str. #223 to ensure negligible sediment -laden runoff reaches Str. #223. Str. #223 makes direct connection with UBP, an aesthetic amenity that provides habitat and quality/quantity Mgmt. (4 x WQV) for 43± on- site /110± off -site Ac. (sheets 9, 10; WPO201400004). Revise site, road, and VSMP plans using notes, labels, details, and sequence to state that until all upslope areas requiring ESC control are stabilized ([control] via Ex. Sediment basin approved under WPO201400004 /proposed to be modified under WPO201500042), only pipe #223A may be shown as an outfall from Str. #223 (sheet 3). Str. #223A is proposed to replace Ex. Str. 156A. Note: This topic was discussed in detail in email Q. Anderson, 5/21/2015 6:46 AM) and Initial Site Plan comments, SDP201500015, 20 -May 2015, items 8, 9, 12, 13, 15, 17, 21. There is no discernible response to ISP comments on this point. Please review ISP comments (SDP201500015) and 5/21/2015 email, and revise VSMP /WPO plan accordingly. Please call if any questions. (Rev. 1) Addressed via redesign. As follow-up, please include language from RGA comment response letter in Note, sheets 4, 8. Please revise Notes to read [sheet 4/8]: "Str. #229 will not be built until all upslope areas draining to Str. #228 are stabilized, and the Ex. Sediment Basin is removed, per County Inspector approval. These upslope areas include all of the contributing runoff from block 27 and future blocks 7, 6, 26 and 35." Also: SHEET 3: Please remove /delete note that reads: "Upon site stabilization, install permanent outfall into Upper Ballard Pond (Str. #229 - #230) & remove temp. pipe Str#231 and Str#232." This note may be misconstrued. 4. Reconcile storm sewer profile Ex. #144 - #230 (outfall) with plan view. In profile view, please revise to show riprap outfall protection above rather than below Upper Ballard Pond Normal WSE = 672.60' —and ending at water's edge. (Rev. 1) Addressed. 5. Ref, Final Site Plan comments, SDP201500035. Revise design accordingly. (Rev. 1) Addressed. C. VSMP: SWPPP: Erosion Control Plan (WPO201500042) Virginia Code §62.1- 44.15:55 requires the VESCP authority to approve or disapprove an ESOP. This plan is disapproved for reasons provided in comments below. The erosion control plan content requirements can be found in County Code section 17 -402. 1. Copy profile, Ex. Sediment basin, from WPO201400004 to this plan (pai4i ' image, bolo ). (Rev. 1) Addressed. Engineering Review Comments Page 3 of 6 2. Provide plan/profile of proposed modified Ex. Sediment basin, similar to images below (unrelated project). (Rev. 1) Not Addressed, as requested. Please ref. images below. Also, please ref. email 10/28/2015 4:39 AM — Email requests design "ensure profile views are drawn with horizontal compression not more than 4X vertical scale: for example, if 1" =5' vert, then 1" =20' horizontal, Max." Plans submitted 1 -Oct cannot reflect 28 -Oct email request, but revisions do not respond to comment request. Please revise modified sediment basin profile, as requested. SEDIMENT BASIN #3 67OPS0111. NT5 FJBSTING GROUND �6 GAGE TEMPOMRYCMP TOPOFDAM ELEV. =3�fi.oa' J��6 ACK DEVICE ySYR. STORM �.o•rvlln. EMERGENCYSPILLWAY - -._ -. - - ELEV•3 7� CRESTELEV, -3� 7i _ - -•••ro � -r =� MIN. x'OIA. CL III RCP RISER OEVK:E, ELEV •3 -Z'— BMOM OF BASI UPSTREAMT9E DF DAM EEEV•3�95� ELEV•3�950 CONCRETE FOCNDATION W Till III EMBEDDED III INTO TNECONCREW 1W. IN =p&7x'� [z} 7C33' GALY. STEM ANTI -SEEP COLLARS 4 YSCARIREU KEY FOR —SO4COHERON '1NV. PUT • 325a' HOSTING GROUND f OUTLET PROTE[TION IIjfJ CLAY RED 6 K NTO THE E EYED EMSTINGGROUND y{' CL II RCP LENGTNga' SLOPEn. % SEDIMENT BASIN #3 PROFILE (SCALE �" =40) IROPOSED &�tL III RAPBARRE1,72LF;�DAM 326.00' INVERT IN= 316;7fi INVERT OI TF 3sfi.00` RIM "CL. III RCP 394 Xf INGGRADE r E 3�1Mp�c. IN FL = 319.50 PROI 1i 0 PROTECTION ; m m m m tai m m 0+50 1+00 1 +rj0 2 +00 2 +2S SEDIMENT BASIN #3 DETAIL IsaEEi+m UNDERLAYMENT Engineering Review Comments Page 4 of 6 r 9.Sa PR � f _ PROPOSED q "CL III ....� D c - � � fA15ERWM ELEVA7gN 60 IS ..63 AGGREGATE CUTLET -�`f T/ I'm ETOPOF[UNTEIfVATIWF /' TERI r /GEOTEA7ILE FILTER FABRIC J]11 25'. D_2, 1(I NOER[AYMEIR L�1'. N1 *$,]5'. V,MIN . j H / - Y �ROPOSED.NI 3V // RCP BARREL, p LF / r! / INVERT IN•3s5,p'� PROPOSED SS w'OE GR0.ALINEO EME�GFNCV - -- INVERTOUT- 3A.RR' l J{ _ / SPRY CREST ELEVATION" 7j . COJ�i ACTOR SHALL N07- PRO EDVDW.3 roAhM AGGIf CG CUTLET- 'S4/ // d O ILANDS[TYP'j / PR6TElTlON w /GEOIF]RNEFILiE -RIC J J J ( I/NDERIAYMENi IL�2 %M 3.75, Y12a13.2R', 0�' MIN.) // 3. Recommend additional contour labels. (Rev. 1) Addressed. 4. Sheet 5 — Provide yard inlet /s in open space to protect dwellings against peak storm runoff events. (Rev. 1) Addressed. 5. Sheet 7 — Revise text: a. Project Description: Although the existing sediment basin was "sized to accommodate all of the western area development," it is proposed to be modified, and then removed in Phase II. This circumstance is addressed at length in RP comments. Revise narrative description to at least be consistent with Sequence of Construction Item #3 (Ex. Basin to be regraded). Consider effect of basin regrading. (Rev. 1) Addressed. b. Sequence of Construction i. RGA/PE and contractor shall verify functionality of existing sediment basin. (Rev. 1) Addressed. ii. Revise item #3 consistent with plan sheet 3, which states Str. #156A will be replaced, not extended. Plan view shows replacement, not extension. Also, 4165A, typo. (Rev. 1) Addressed. As follow -up, seq.constr.note #4: please insert this statement between sentences 1 and 2: "Remove existing temporary storm pipe (Str. #156A) and outfall (see sheet 3)." Also, please edit seq.cosntr.note #4, sentence 2, to read: "Re -grade the existing sediment basin and install the proposed storm sewer system (pipe Str. #226 -MH Str. #228) and the..." iii. Revise sequence item #7 to read "Upon site stabilization of all upslope areas, including future blocks, draining to Str. #223, install permanent outfall into Upper Ballard Pond." (Rev. 1) Addressed. iv. Move revised item #7 to later point in sequence of construction. (Rev. 1) Addressed. v. Revise item #8 to read: "Permanent soil stabilization shall be applied to all denuded areas within seven days after final grade is reached on any portion of the site. Temporary soil stabilization shall be..." (Rev. 1) Addressed. vi. Include description of ESC measures designed to prevent impact to UBP during installation of outfall to UBP. (Rev. 1) Addressed. Engineering Review Comments Page 5 of 6 c. Calculations - Revise text. No water quality calculations are included or required with application. (WP0201400004 indicates water quality compliance - statement to this effect may be helpful.) (Rev. 1) Addressed. 6. Sheet 7 - Remove inlet schedule. Remove storm sewer schedule. (Rev. 1) Addressed. 7. Provide data for proposed modified Ex. Sediment basin, similar to data in chart-table below: (Rev. 1) Not Addressed. There is value in collecting and organizing design information. The proposed modified existing sediment basin does not have an emergency spillway. The 25 -yr WSE = 681.00. This elevation is 11.73' higher than the pipe invert beneath Old Trail Drive, is either 4.25' or 1.15' higher than top of riser (two riser top elevations listed), and is approx. 4.1' above crown of 42" temporary storm pipe leading to the sediment basin. Please provide organized tabular information as requested. Please revise riser top elevation. $Wiirwnt Basin #3 Design rtecArraniEwAr dramige area facres) 6.34 nrsacx WGMv Arre "M r NY- besin volumes: (using 2' contour internals] 970. °fY elmOoh (ft) oorMur area (sf) -Lkr- W a, 399:50 41220 0 , MOO 4456.0 79.4 na mw E r� CFW 322.0(1 5$43.0 459.4 a°rn 324.00 7350.0 947.3 326:00 awoo o 1551.4 - wet ggtM - fsk- 68requi red f yr):f67. 424:5 desThtgh.waW..M 82FL75 deniaftdnq ari6ee e6AA fiion M Wgi of dam 06 326.00 vVA. a PrMed at fxs , alaiati *J Yl h* width of dmn mi" volarW before c6anbut (oy) (WDA) MO bottorniafli6aim ( ft) 3'10.6 ctearad de adon (ft) 3id0:70. oppro), bottom drmenOoro: W3T distance fr4m.c6 armvktn. I�IC''`1'� 1:'f upshearnfaceslope: �1 drV SfOreQe' dwmstream face slope: dry 8torage re4K?trw (PO WIQN 424.8 baf & YM prix -_! spi y cre&1 jRj 323.75 Length of flow; L (ft) 911 dry. storage prorddetl &t this e q � 461 effaurne ukth,`We (ft) 29 diameter of devstafirrog orifices AD L 1 Vr a : {beles not required if > 4) 9.2 diameter of flemble tubing (in)(ritlf 640) .. 70 collars: YES depth of m'VW at spillway Crest (fo 425 0".045 for bare eat) as slope of WSIT"m face �Z. 1} 4. 71:3: slope of barrel (3b]: % yf ... _ q 2# 15.63 lepggh of barrel in @iatur *d zone (La) 29.W 1 r• 09 eozyr 27.02 nurrbar colars mWired 2 dintension.of collars 3.3rGi 3' saus8 'l rfC In 23 emergancu.soatvav_ YES ffdar{fi j 24 fecluir®d capacity (Q2640.(d.s� ' 2.64 'eapw4v W 16.0 bomm.W tth yo 45 d6relaar hesh reekiin) 8fi Nape of a ist.cdrerrtef (fNfU 25% rtprrel (f3) 72_. rrliriimun kn* of w*chattY* ft 41. head w hOrreEYf+mKo wti&Ytkrt'entN &73 crastof =pl" (fo 324.75 d18mw of in .. ...... 8. Future block 7 development has been discussed with County Engineer. Please anticipate trap or basin measures with future block 7, with ESC measures located outside buffers, without runoff release to storm inlets /pipes, with emergency spillway or weir (trap) that releases peak runoff event at non - erosive velocity at a point at least 100' from UBP. (Rev. 1) Applicant response, 29 -Sep, 2015: "We will consider the future Block 7 development and ESC measures that will need to be associated with it." D. VSMP: Mitigation Plan The mitigation plan requirements can be found in County Code section 17 -406. 1. Sheet 3 -Label stream buffer, Upper Ballard Pond. (Rev. 1) Addressed. 2. Show, calculate, and propose Mitigation for stream buffer impact associated with outfall constr. to UBP. (Rev. 1) Addressed. Engineering Review Comments Page 6 of 6 3. Provide mitigation at 2:1 ratio. (Rev. 1) Addressed. Engineering plan review staff are available from 2 -4 PM on Thursdays, should you wish to discuss this review. Plan review staff are also available at 434 - 296 -5832 (- x3069) should you have questions. Process: After approval, plans will need to be bonded. The bonding process is begun by submitting a bond estimate request form and fee to the Department of Community Development. One of the plan reviewers will prepare estimates and check parcel and easement information based on the approved plans. The County's Management Analyst will prepare bond agreement forms, which will need to be completed by the owner and submitted along with cash, certificates or sureties for the amounts specified. The agreements will need to be approved and signed by the County Attorney and County Engineer. This may take 2 -4 weeks to obtain all the correct signatures and forms. Stormwater Management Facilities Maintenance agreements will also need to be completed and recorded. The County's Management Analyst or other staff will prepare the forms and check for ownership and signature information. The completed forms will need to be submitted along with court recording fees. After bonding and agreements are complete, the County can hold a pre - construction conference. Applicants will need to request a pre - construction conference by completing a form, and pay the remainder of the application fee. The form identifies the contractor and responsible land disturber, and the fee remaining to be paid. This will be checked by county staff, and upon approval, a pre - construction conference will be scheduled with the County inspector. At the pre - construction conference, should everything proceed satisfactorily, a joint VSMP and grading permit will be issued by the County so that work may begin. County forms can be found on the county website forms center under engineering; htW : / /www.albemarle.orgJdeptforms .asp ?department--cdengnoo Thank you - 434.296 -5832 —x3069 File: WP0201500042 Old Trail -block 27 110215revl