HomeMy WebLinkAboutWPO201400045 Review Comments Erosion Control Plan 2014-06-23pF A
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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 review
Project:
Personal Wireless Facility —Royal Orchard
Plan preparer:
Cheryl Lynn Taylor, Velocitel [4144 Innslake Drive, Glen Allen, VA 23060
c.taylor(&velocitel.com]; Christopher D. Morin, PE, BC Architects Engineers
[5661 Columbia Pike, Suite 200, Falls Church, VA 22041 -
cmorinLbcplc.com]
Owner or rep.:
Commonwealth of Virginia, VA Dept of Transportation [701 VDOT Way,
Charlottesville VA 22911- joel.denunzio(a)vdot.vir ig nia.gov]
Plan received date:
12 May 2014
(Rev. 1)
9 February 2015
Date of comments:
23 June 2014
(Rev. 1)
18 February 2015
Reviewer:
John Anderson
NOTE: Revised plans received 9 -Feb are response to 23- Jun -14 comments. Last fall, 2014, there was coordination
between Applicant and ACCD concerning access road design/alignment and max allowable grades to minimize
critical slope impacts, in support of critical slopes waiver request. Comments below are generally independent of
that coordinated effort to evaluate Applicant's critical slopes waiver request. SWM plan/report details are source of
majority of comments. Please consider SWPPP/ESC /SWM plan review comments; please call if any questions:
A. Stormwater Pollution Prevention Plan — Pollution Prevention Plan (SWPPP /PPP)
The SWPPP content requirements can be found in County Code section 17 -405. The PPP content
requirements can be found in County Code section 17 -404. A SWPPP must contain (1) a PPP, (2)
an ESOP, (3) a SWMP, and (4) any TMDL measures necessary.
1. Please complete Single Family Residence Common Plan of Development or Sale Stormwater
Pollution Prevention Form (SWPPP) sent as Attachment with plan review comments, 18- Feb -15.
(link:
httn: / /www.dea.virainia.eov/ Portals /0 /DEO/ Water /StormwaterManaeement /CPoD SWPPP SFR
201407.docx ). This template is the least time - consuming approach available. [17 -404, 17 -405]
2. SWPPP should include bioretention filter maintenance activities (Table 9.7NA DEQ Spec. #9)
B. VSMP: SWPPP: Stormwater Management Plan (WP0201400045)
VSMP Regulation 9VAC25- 870 -108 requires the VSMP authority to approve or disapprove a SWMP. This plan
is disapproved for reasons provided in comments below. The stormwater management plan content requirements
can be found in County Code section 17 -403.
Under current Water Protection Ordinance (WPO), SWM plan approval of this project design is required
prior to land disturbance. Current WPO stipulates water quality requirements for any land disturbance,
including < 10,000 ft2. Note: this memo relates to ESC plan only since review not requested (nor fee paid)
for SWM plan review, yet it would be remiss not to comment on SWM aspects of this project since report
titled Stormwater Management and Best Management Practices dated March 20, 2014, accompanies
project plans titled Site Name: CV479, dated April 17, 2014. The report references low impact design and
Engineering Review Comments
Page 2 of 7
includes SCS hydrologic model data (10 -yr, 24 -hr storm), culvert analysis, narrative, map /contour data, and
other details relating to SWM. Please accept comments in this section as a courtesy while noting that a
SWM plan review application has not been submitted (only an ESC plan). (Rev. 1) Comment addressed
– VSMP Application submitted.
2. If a SWM plan application is submitted at this point, review will not be complete prior to July 1, 2014.
Beginning July 1, 2014, "Land disturbing activities that disturb less than ten thousand (10,000) square feet
of land area except for land disturbing activities that are part of a larger common plan of development or
sale that is ten thousand (10,000) square feet or greater of disturbance" are exempt from VSMP permit
requirements [ref. AC Code Sec. 17 -303. D., Eff. 7/1/14]. This means that current project design estimated
to disturb approximately 12,200 SF (0.28 Ac.; p. 3 /report) would be subject to VSMP requirements, but a
revised design that disturbs <10.000 SF would be exempt. There are ways to limit disturbance, including
review of LOD shown on drawing E &S -2 down slope of the monopole /shelter area. LOD is shown in areas
in which existing contours do not change —is it possible via careful construction to limit LOD below the
shelter? Or, would it be possible to continue to follow the existing access road further south and limit road
area impact? Or, without immediately clear implications, could portions of the existing access road (that
will be abandoned) be restored to a natural condition? This would increase LOD but would reduce site
impervious area. This option presents temporary disturbance, and while long -term benefit exists, there is no
apparent mechanism to exempt disturbance required to convert sections of the existing gravel -dirt road to a
natural state. Under any re- design that limits area of land disturbance to less than 10,000 SF, applicant may
request in writing (attaching revised design) whether project is subject to Ch. 17, Article III ( "Applicability
of the VESCP and the VSMP "; ref. 17 -300, eff. July 1, 2014). This would be a request based upon design
< 10, 000 SF, not a permit application, and would not require a review fee. (Rev. 1) Comment addressed
– VSMP Application submitted.
3. If applicant elects to submit a SWM plan review application with plan details or narrative that indicate land
disturbance >10,000 SF, application will be reviewed in accord with WPO, rev. eff. 7/1/14. All applicable
fees and review, construction, and SWM /ESC requirements would apply, including water quality, water
quantity, and stormwater pollution prevention. In that case, plan, modeling, runoff reduction spreadsheet,
and narrative elements beyond data submitted with current ESC plan application would be required. We
could discuss this option via phone. (Rev. 1) Comment addressed.
4. Report statement (p. 4) that "there is no requirement for water quality devices for this site" is inaccurate
under current WPO (no exemption for quality; see AC 17 -300, 17 -315), and appears inaccurately applied
under the new WPO. This is new development under VAC, not prior developed lands –see 9VAC25 -870-
63, 9VAC25- 870 -65. (Rev. 1) Comment addressed – VSMP Application submitted.
5. If applicant elects re- design that limits land disturbance to <10,000 SF, please reference existing soil - gravel
road. Exclude area of proposed 12 -ft access road that follows centerline of existing soil - gravel road. Do,
however, include additional land disturbance due to widening existing soil - gravel road, if widening is
proposed (it appears not to be). (Rev. 1) Comment addressed –VSMP Application submitted; estimated
land disturbance >10,000 SF.
New (or Follow -up)
Include STORMWATER MANAGEMENT PLAN in plan set title.
2. Number all pg. of SWM and BMP Report. Within exhibits, please hand - number pgs. For example: Exhibit
1, Soils Information – number these 5 -pg: 9 -a, -b, -c, -d, -e. It is difficult to correlate comments and report.
Engineering Review Comments
Page 3 of 7
3. Check/revise SCALE on all sheets — existing scale is unusable for plan review. For example, no standard
scale (1" = 10, 20, 30, 40, 50, 60') can be used to readily check 12' drive width, E &S -1. Revise scales on
sheets E &S -1, -2, -4, etc. Adopt 1" = 20', or similar standard scale (existing: 2.1" = 30'f).
4. Revise T., DA -2: 24.9 and 25.0 minutes are inconsistent with VESCH, given site conditions. Ref.
OVERLAND FLOW TIME, VESCH, Plate 5 -1. VESCH indicates overland flow (DA2) will range <10 min
(Ave grass surface) to 12 min (Dense grass surface). County GIS photometric data does not indicate dense
underbrush, or dense grass (image, below). Existing condition at forest floor may approach bare soil,
which, at this far extreme, yields T, « 10 min. Use T, = 12 min, max, or present rationale for alternate
calculation. VESCH is the default. Design calculations should reflect VESCH methods, and
proposed /existing conditions.
5. Tc =24.9 min. is unacceptable. Revise routings. Revise bioretention design. Also, New #4, above.
6. Bioretention basin design and location are problematic:
a. Ref VA DEQ Stormwater Design Specification No. 9, Level 2. Revise design to include:
i. Sub -soil testing
ii. A 2 -cell design (Geometry)
iii. Pre - treatment (must include gravel diaphragm, or equivalent, between gravel access road,
and BMP, to keep stone from washing into BMP). Note: design proposes to stabilize cut
slopes >3:1 with riprap, not vegetation. Underlying soil will be armored, but without root
system to anchor slopes, anticipate transport off cut slopes, to ditch lines, to BMP.
Anticipated sediment transport may affect performance of proposed bioretention
treatment. Pre - treatment is essential. -Also, item # C. New 19, below.
iv. Planting plan: "...If using turf, must combine with other types of vegetation." (Spec #9,
6.8) Furnish Level 2 bioretention planting plan.
Engineering Review Comments
Page 4 of 7
Bioretention filter construction Note 1 (E &S -8) reads: "The construction of the proposed
bioretention filter shall conform to the Virginia DCR Stormwater Design Specification
No. 9. Contact the design engineer if more information is needed." This note is
inadequate. Revise. Include Specification #9, Sec. 8.2, steps 1. -12., with accompanying
figures. Plan approval is contingent upon clear, comprehensive, explicit instructions.
vi. Table 9.7, E &S -8 (from VA DEQ Spec. #9), references pre - treatment cells. Furnish pre-
treatment cells (Also, iii, above).
vii. Table 9.7, E &S -8, references 3 -inch mulch layer. No mulch is visible in bioretention
filter cross - section. (E &S -7).
b. Revise Report, Exhibit 7, BIORETENTION FILTER CROSS SECTION AND DESIGN CRITERIA Drawing: 4"
0 perforated pipe INV label reads "INV. = 724.00'— See Note 7." Inv. Elev. is inaccurate; also,
cannot find Note 7.
c. Revise contours in vicinity of bioretention filter: 2 sets of proposed contours [E &S -2, -6; Also,
item # C. New l.c., below]. Revise sheets in SWM and BMP Report (20Mar -14; rev. 21- Jan -15).
d. Note: Micro - bioretention (design) may offer certain advantages.
7. Minor: Revise titles /drawing numbers, sheets E &S -6, -7, -8, -9 to ref. SWM, and SWM Plan (v. `Pages
from Stormwater Report') We must approve a SWM plan.
8. E &S -6 /Drainage Area Map: DA 1 Managed turf =0.09 Ac.; DA 2 Managed turf =0.02 Ac. Total site areas
in VRRM Calculations: Managed turf =0.24 Ac. Reconcile values: 0.11 and 0.24 Ac.
9. Revise VaRRM .xls, to reflect revised Managed turf.
10. Revise bioretention basin design, as necessary, to reflect revised Managed turf.
11. SWM and BMP report, p. 3, states compound area will be cleared of existing vegetation. Specify /show
proposed final material surface for monopole compound (image below).
12. SWM and BMP report, p. 4: "The results of all hydrologic calculations are contained in Exhibit 5." Exhibit
5 presents hydrologic/hydraulic analysis of 2 culverts, but may exclude ditch flow on the west side of access
drive. At sta. 2 +75f, a level spreader on the west side disperses ditch flow. Typical access road cross
section #2 (A -6) may cover this section, may divert runoff to ditch line on east side of road; several items
require revision, or clarification: i) confirm DA 1, E &S -6, is accurate; that is, access road slopes east; ii)
label typical access road cross sections # 1 and #2 with stationing; iii) provide access road stationing at 50-
ft intervals and major grade breaks on sheets E &S -1, -2; iv) confirm runoff exiting roadway to the west is
non - concentrated sheet flow that enters woods; v) confirm level spreader on east side of road above inlet of
culvert #1 disperses ditch flow into the woods; vi) and, if so, how this fact is treated or accounted for in
Exhibit 5 calculations.
13. Confirm that Exhibit 5 is accurate relative to runoff that is dispersed using level spreaders. This flow
appears to bypass treatment (bioretention filter).
Image — comment #11.
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Engineering Review Comments
Page 5 of 7
C. VSMP: SWPPP: Erosion Control Plan (WPO201400045)
Virginia Code §62.1- 44.15:55 requires the VESCP authority to approve or disapprove an ESCP. 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. Include Typical Access Road Cross Section #1 and Typical Access Road Cross Section #2 with plan sheets,
not just the report. Report details will not inform contractor or construction unless included with plans.
(Rev. 1) Comment addressed.
2. Revise road grade to east of new access road, sheet E &S -2, consistent with typical cross section, detail #2.
That is, contours should indicate a ditch -line on the east side of certain sections of the new access road.
(Rev. 1) Comment addressed.
3. Include Culvert Erosion Protection Detail with plan sheets, not just the report. Show culvert inlet protection
on all culvert inlets (CIP). Show outlet protection (OP) on all outlets. Show [symbols /rev. I] on plan
sheets. (Rev. 1) Comment partially addressed. —Also, item # New 18, below.
4. Project must minimize impact to critical slopes ( >25 %). The wireless monopole and equipment shelter
occupy critical slopes. Ensure that design (sheets A -1 and E &S -2) minimizes impact to critical slopes to
extent practicable. Ref. Albemarle County Design Standards Manual, Section 8, for grading requirements
for steep slopes, including maximum grade and vegetative stabilization. Constructed slopes steeper than 2:1
must have a waiver from the county engineer. [link:
hlW: / /www.albemarle.ora/ department .asp ?department= cdd &rel2aae =4447 ] (Rev. 1) Comment
addressed.
5. Identify any off -site borrow or waste sites. (Rev. 1) Comment addressed
Engineering Review Comments
Page 6 of 7
6. Show stockpile and construction staging areas on plan sheets. Show temporary and permanent seeding,
mulch, and dust control areas on plan sheets (indicate using symbols: TS, PS, MU, and DG). Note: slopes
steeper than 3:1 must be permanently stabilized with landscaping vegetation hardier than grass, which will
not require mowing [Albemarle County Design Manual]. (Rev. 1) Comment partially addressed —Also,
item # New 11, below.
7. Note: Culvert 1 with qlo =.34 cfs, vet = 2.34 fps, has a wetted area = 18.5% of pipe cross - sectional area.
Culvert 2 with q,o = .40 cfs, vet = 2.79 fps, has a wetted area = 18.25 %. 12" DIA culverts appear adequate
to meet design flow in each case. (Rev. 1) As follow -up, see item # New 2, below.
New (or Follow -up)
1. Contours:
a. Extend contours at least 50' beyond roadside ditch lines. In places, contours extend no more than
30' from road. [ES -1, -2]
b. Extend arrowhead of New Contours (Typ) label to point to new contours. Arrowhead points to
existing contours. [ES -2]
c. Revise contours in vicinity of proposed bioretention filter. Two sets of proposed contours shown.
d. Expand LOD consistent with realistic limits of disturbance. Revise contours consistent with
realistic LOD. Also, #16, below.
e. Revise contours at level spreaders, consistent with E &S -3, Level Spreader details, perspective
view. Show proposed grade required to construct a transition to zero grade, and zero grade. Also,
#3, below.
f. Revise and show (proposed final) contours between edge of bioretention filter and outlet of 36'-
10" bioretention filter outfall pipe — compare E &S -2, -6 with BMP cross section A -A (E &S -7).
2. Provide Additional Detail to support Culvert Designer /Analyzer Reports, culverts 1 and 2. Present detailed
calculations that will tie HydroCAD post - developed flow regimes to pipe capacity, exit velocity. Summary,
grades, hydraulic profile, section, and outlet /inlet control properties are data, or variables and constraints.
Show equations used to calculate pipe exit velocity; tie to Qlo. Use Mannings, or appropriate alternative.
3. Ref BMP Clearinghouse Stormwater Design Specification No. 2 (Sections 3, 4, 6.3) for Engineered Level
Spreader (ELS) design. Revise level spreader design to conform to available designs found in this BMP
specification. For example: L = 13' /cfs. Specify dimensions, materials, etc. Revise proposed contours,
E &S -1, -2, consistent with ELS design. Transfer BMP ELS specification details to plan sheets.
4. Clarify "Permanent TRM bury 6 -in. Min" label, E &S -3. Do not abbreviate TRM. Meaning is unclear.
5. Runoff will not exit ditch at 90 -deg angle to cross ELS without diversion or structure of some type. Detail
mechanism or structure for diverting ditch flow to ELS, E &S -1, -2.
6. Revise E &S -1, -2 legends to include rock -lined stormwater conveyance channels with EC -2/3 matting (road
side ditch lines). E &S -4 profile shows proposed access grades are steep with few exceptions: varying 11.91
to 30.00 %. [ -ref Albemarle County Final Plan General Note, 6.]
Engineering Review Comments
Page 7 of 7
7. Furnish, specify, and show (plan view, E &S -2) VDOT pipe end - sections for culvert 1, 2, and bioretention
outfall pipe.
8. Specify and show INV /in -out ELEV, and pipe length (L), all pipes listed in #7, above.
9. Provide typical road cross section at culverts 1 -2, sheet A -6. Show depth of cover above 12" pipe.
10. Dimension height /width of runoff conveyance channel (ditch), Typical Access road cross section #2, A -6.
11. Revise E &S sheet legends to include: SCC ( #6, above), MU, CD ( #10), IP /OP ( #17, below).
12. Proposed SF (contour 1715', E &S -2) serves no practical purpose. Revise placement of SF, this location.
13. Symbols (SF, chain link fence, tree protection ?) south of monopole location are unrecognizable. Please
clarify symbols, or purpose. Revise E &S legend to include all E &S symbols shown in plan views.
14. Add rock check dams to road side ditches. Slopes range to 30% (3:1 slopes).
15. Furnish rock check dam detail (VESCH).
16. Revise Area of Disturbance (15,708 SF, E &S -1, -2) consistent with SWM and BMP report, p. 3 (15,620
SF).
17. E &S -3 /Culvert Erosion Protection Detail: Dimension inlet protection (IP) (only depth is specified).
18. Show pipe inlet/outlet protection symbols, E &S2 [IP /OP] —Also, #11, above.
19. Proposed slopes steeper than 3:1 require low maintenance (not grass) ground cover; specify vegetative
cover on plans. [Albemarle County Design Standards Manual (ACDSM), 8.A.2.] — Exception: for slopes
steeper than 2:1, show and shade these areas on E &S -1, E &S -2. Riprap for slopes > 2:1 is permissible.
20. Revise plan view Notes that read: " Riprap all cut slopes greater than 3:1 w/ Class I riprap" to read "greater
than 2:1" consistent with #19, above. There are at least three occurrences of this note.
21. Hatch or shade cut slopes > 2:1.
22. On E &S -2, if intent of proposed diversion ditch is to prevent clean, off -site runoff from reaching area of
disturbance, DD should be shifted to a point above proposed steeply graded sections shown on E &S -2,
revise.
23. Sheet A -0: Check drawing scale (appears inaccurate). Please revise scale.
24. Sheet A -0: Revise sheet title. A site plan cannot be approved as part of a VSMP Application. Use title
other than `site plan.'
File: WP0201400045- Wireless Facility -Royal Orchard -AT &T Site CV479- 021815_revl
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COUNTY OF ALBEMARLE
Department of Community Development
401 McIntire Road, Room 227
Charlottesville, Virginia 22902 -4596
Phone (434) 296 -5832 Fax (434) 972 -4126
Project:
Personal Wireless Facility –Royal Orchard
Plan preparer:
Cheryl Lynn Taylor, Velocitel [4144 Innslake Drive, Glen Allen, VA 23060
c.tUlor(d)velocitel.comb Christopher D. Morin, PE, BC Architects Engineers
[5661 Columbia Pike, Suite 200, Falls Church, VA 22041 -
cmorin(c)bc]2lc.com]
Owner or rep.:
Commonwealth of Virginia, VA Dept of Transportation [701 VDOT Way,
Charlottesville VA 22911- ioel.denunzio&vdot.vir ig nia og_v]
Plan received date:
12 May 2014
Date of comments:
23 June 2014
Reviewer:
John Anderson
A. Stormwater Management – Guidance comments
Under current Water Protection Ordinance (WPO), SWM plan approval of this project design is required
prior to land disturbance. Current WPO stipulates water quality requirements for any land disturbance,
including < 10,000 ft2. Note: this memo relates to ESC plan only since review not requested (nor fee paid)
for SWM plan review, yet it would be remiss not to comment on SWM aspects of this project since report
titled Stormwater Management and Best Management Practices dated March 20, 2014, accompanies
project plans titled Site Name: CV479, dated April 17, 2014. The report references low impact design and
includes SCS hydrologic model data (10 -yr, 24 -hr storm), culvert analysis, narrative, map /contour data, and
other details relating to SWM. Please accept comments in this section as a courtesy while noting that a
SWM plan review application has not been submitted (only an ESC plan).
2. If a SWM plan application is submitted at this point, review will not be complete prior to July 1, 2014.
Beginning July 1, 2014, "Land disturbing activities that disturb less than ten thousand (10,000) square feet
of land area except for land disturbing activities that are part of a larger common plan of development or
sale that is ten thousand (10,000) square feet or greater of disturbance" are exempt from VSMP permit
requirements [ref. AC Code Sec. 17 -303. D., Eff. 7/1/14]. This means that current project design estimated
to disturb approximately 12,200 SF (0.28 Ac.; p. 3 /report) would be subject to VSMP requirements, but a
revised design that disturbs <10.000 SF would be exempt. There are ways to limit disturbance, including
review of LOD shown on drawing E &S -2 down slope of the monopole /shelter area. LOD is shown in areas
in which existing contours do not change —is it possible via careful construction to limit LOD below the
shelter? Or, would it be possible to continue to follow the existing access road further south and limit road
area impact? Or, without immediately clear implications, could portions of the existing access road (that
will be abandoned) be restored to a natural condition? This would increase LOD but would reduce site
impervious area. This option presents temporary disturbance, and while long -term benefit exists, there is no
apparent mechanism to exempt disturbance required to convert sections of the existing gravel -dirt road to a
natural state. Under any re- design that limits area of land disturbance to less than 10,000 SF, applicant may
request in writing (attaching revised design) whether project is subject to Ch. 17, Article III ( "Applicability
of the VESCP and the VSMP "; ref. 17 -300, eff. July 1, 2014). This would be a request based upon design
<10, 000 SF, not a permit application, and would not require a review fee.
Engineering Review Comments
Page 2 of 2
3. If applicant elects to submit a SWM plan review application with plan details or narrative that indicate land
disturbance >10,000 SF, application will be reviewed in accord with WPO, rev. off. 7/1/14. All applicable
fees and review, construction, and SWM/ESC requirements would apply, including water quality, water
quantity, and stormwater pollution prevention. In that case, plan, modeling, runoff reduction spreadsheet,
and narrative elements beyond data submitted with current ESC plan application would be required. We
could discuss this option via phone.
4. Report statement (p. 4) that "there is no requirement for water quality devices for this site" is inaccurate
under current WPO (no exemption for quality; see AC 17 -300, 17 -315), and appears inaccurately applied
under the new WPO. This is new development under VAC, not prior developed lands —see 9VAC25 -870-
63, 9VAC25- 870 -65.
5. If applicant elects re- design that limits land disturbance to <I0,000 SF, please reference existing soil - gravel
road. Exclude area of proposed 12 -ft access road that follows centerline of existing soil - gravel road. Do,
however, include additional land disturbance due to widening existing soil - gravel road, if widening is
proposed (it appears not to be)
B. Erosion Control Plan (WPO201400045)
1. Include Typical Access Road Cross Section #1 and Typical Access Road Cross Section #2 with plan sheets,
not just the report. Report details will not inform contractor or construction unless included with plans.
2. Revise road grade to east of new access road, sheet E &S -2, consistent with typical cross section, detail #2.
That is, contours should indicate a ditch -line on the east side of certain sections of the new access road.
3. Include Culvert Erosion Protection Detail with plan sheets, not just the report. Show culvert inlet protection
on all culvert inlets (CIP). Show outlet protection (OP) on all outlets. Show on plan sheets.
4. Project must minimize impact to critical slopes ( >25 %). The wireless monopole and equipment shelter
occupy critical slopes. Ensure that design (sheets A -1 and E &S -2) minimizes impact to critical slopes to
extent practicable. Ref. Albemarle County Design Standards Manual, Section 8, for grading requirements
for steep slopes, including maximum grade and vegetative stabilization. Constructed slopes steeper than 2:1
must have a waiver from the county engineer. [link:
http: / /www.albemarle.org/department .asp ?department= cdd &relpage =4447 ]
5. Identify any off -site borrow or waste sites.
6. Show stockpile and construction staging areas on plan sheets. Show temporary and permanent seeding,
mulch, and dust control areas on plan sheets (indicate using symbols: TS, PS, MU, and DC). Note: slopes
steeper than 3:1 must be permanently stabilized with landscaping vegetation hardier than grass, which will
not require mowing [Albemarle County Design Manual].
Note: Culvert 1 with qlo =.34 cfs, vel = 2.34 fps, has a wetted area = 18.5% of pipe cross - sectional area.
Culvert 2 with qlo = .40 cfs, vet = 2.79 fps, has a wetted area = 18.25 %. 12" DIA culverts appear adequate
to meet design flow in each case.
File: WPO201400045- Wirelesss Facility -Royal Orchard -AT &T Site CV479- 062314.doc