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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:
Glenmore Section K2C
Plan preparer:
Ammy George, Roudabush, Gale & Assoc, Inc [914 Monticello Road,
Charlottesville, VA 22902, AGeorge(a)roudabush.com]
Owner or rep.:
Glenmore Associates Limited Partnership, P.O. Box 7623
Charlottesville, VA 22906
Plan received date:
19 Nov 2014
Date of comments:
9 Dec 2014, ESCP
30 Dec 2014, VSMP
Reviewer:
Max Greene, ESCP
John Anderson, VSMP
County Code section 17 -410 and Virginia Code §62.1- 44.15:34 require the VSMP authority to act on any VSMP
permit by issuing a project approval or denial. This project is denied. The rationale is given in the comments below.
The application may be resubmitted for approval if all of the items below are satisfactorily addressed. The VSMP
application content requirements can be found in County Code section 17 -401.
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 ESOP, (3) a SWMP, and (4) any TMDL measures necessary.
1. ACCD SWPPP template SWPPP included with Application —thank you. Sheet 27 of ESC /SWM
plan may remain with plans.
2. In certain respects, template is incomplete. Please review, complete /revise as necessary *:
a. Sec. I /REGISTRATION STATEMENT— provide. Please consider entire subdivision, Areas
subject to VSMP regulations. There does not appear to be a General VPDES Permit
issued to Glenmore Subdivision. Please report Development Area required to be covered
by VPDES (item #9, Acres). Report Disturbed Area for all areas that require VPDES
permit coverage. Also, show Disturbed Area (Acres) associated with Glenmore Sec.
K2C plans (12.8 Ac. per SWPPP /Sec. 3; report this figure on ESC /SWM plans). If
Application is for TM parcel 09400 -00 -00 -01600 only, a parcel listed as held by
Glenmore Associates Limited Partnership, and if this is the final development by this
entity within Glenmore Subdivision, then disregard request for Registration Statement
covering land disturbing activities on additional parcels (Glenmore Subdivision at large).
b. Sec. 2/NOTICE OF GENERAL PERMIT COVERAGE /Glenmore Subdivision — provide a copy of the
DEQ coverage letter (when obtained).
c. Sec. YNATURE OF ACTIVITY - County GIS photometric data shows TM parcel 09400- 00 -00-
01600 pre - developed condition is 100% forest. It is not immediately apparent how
development (26 lots) depicted on sheet 26 of ESC /SWM plans will disturb only 12.8 Ac.
given that turf and impervious areas (VaRRM .xIs, DA A, B, C) total 15.87 Ac. Please
revise narrative, as necessary, consistent with plans. —Ref additional SWM plan review
comments, below.
d. Sec. 4 /EROSION AND SEDIMENT CONTROL PLAN — provide a reduced 11 x 17 copy of the latest
ESC plan (May wait until ESCP is approved /do not reference only).
e. Sec. &POLLUTION PREVENTION PLAN — A. Provide a reduced I I x 17 copy of sheet 26; E.
Identify persons responsible for pollution prevention practices; F. Complete (Response
Engineering Review Comments
Page 2 of 6
and Reporting Practices *); G. Complete (Pollution Prevention Awareness *)
f. Sec. 8 /QUALIFIED PERSONNEL —List*
g. Sec. I O /DELEGATION OF AUTHORITY — Complete, if authority delegated.
h. Sec. 11 /GENERAL PERMIT COPY — Provide /Attach 22 -p. 2014 General VPDES permit.
i. Sec. 12 /INSPECTION LOGS — Provide*
( * Comparison with RGA SWPPP, Old Trail Village, block 12, Phase 1, may be helpful. )
B. Pollution Prevention Plan (PPP) - Addressed under Stormwater Pollution Prevention Plan, above.
The PPP content requirements can be found in County Code section 17 -404.
1. Sheet 26 of ESC /SWM plan may remain with plans.
2. Additional —see Section A. (SWPPP), above.
C. Stormwater Management Plan (WP0201400095)
VSMP Regulation 9VAC25- 870 -108 requires the VSMP authority to approve or disapprove a SWMP. This plan is
disapproved, and the reasons are provided in the comments below. The stormwater management plan content
requirements can be found in County Code section 17 -403.
Ms. George, thank you for speaking with me yesterday. As follow -up, please accept review comments-
1. Ref. VDEQ SWM BMPs for design specifications for roof drain disconnect /infiltration. These are separate
BMP practices, which work well in tandem, but must be disconnected, with infiltration pre - treatment, per
BMP specifications. Links: 1) roof disconnect
http: / /www. vwrrc.vt. edu/swc /documents /2013/DEO %20BMP %20 Spec %20No %201 _DISCONNECTION_
Final %20Draft_vl- 9_03012011.pdf ; 2) infiltration -
http: / /www.vwrrc.vt.edu/swc/ documents / 2013 /DEQ %20BMP %2OSpec %2ONo %208 INFILTRATION Fi
nal %20Draft_vl -9 03012011.pdf
Revise BMP connected roof drain - infiltration design. Provide pretreatment, per BMP specification.
2. VaRRM /SITE DATA (sheet 25): 18.6 Ac. post - developed condition is forest (out of total site =36.8 Ac.)
Although possible given amount of Open Space, unless covenants preserve Open Space as permanent
forest, VaRRM may not report these Areas as forest/open space. Note: Utility corridors may be reported as
forest /open space provided they meet DEQ criteria: limited maintenance (mowing not more than 4 X per
year); no portion of corridor converted to impervious area. Provide covenants. Note 2: Take credit for
forested areas within stream buffers; these areas are protected by ordinance.
3. Post developed runoff from (VaRRM .xls) Drainage Area `B' (entire 8.3 Ac.) may or may not reach
Extended Detention `B' depending on final grade relative to drive entrances for Lots 8, 9, 17 -19 /sheet 22.
While this level of detail may not be necessary for road plans (SUB201400215), it is needed to evaluate
drainage area `B', relative to VaRRM .xls. Please furnish close interval contour grade detail for drive
entrances, for these lots.
Downstream channel protection conditions, (sheet 25 — #4 -9)
4. Energy Balance, DA `C', use I.F. = 0.8. VaRRM does not discriminate based on sub - catchments. For
overall project disturbed area > 1 Ac., I.F. = 0.8.
5. Energy Balance, DA `A': compare HydroCAD /p. 6 inflow depth >0.16" with Rv Pre -Day. = 0.09 ". Reconcile.
6. Use CN =77 for all calculations. In multiple training settings, SWM plan reviewers are cautioned against
accepting pre - developed woods listed as fair condition. (hydrologic soil group D /woods /good condition,
TR -55, Table 3 -3)
7. Enter TR -55 Table 3 -4 with CN =77. Use 1" (24 -hr) rain =3_5" (not 2.5 "). If CN =77, rain =2.5" then Rv
Pre -Dev.) = 1.436 ". Revise all calculations /routings —use Rv Pre -Dev. = 1.436 ".
8. Energy Balance, DA `B': compare HydroCAD /p. 8 inflow depth >0.16" with Rv Pre -Dev. = 0.09 ". Reconcile.
—Also #6, #7 —Apply CN /runoff depth/routing comments to DA `B'.
9. Energy Balance, DA `A': compare HydroCAD report/p. 6, 1.68 cfs with (sheet 25) 1.33 cfs. Reconcile.
10. Provide drainage area maps for pre- /post - developed conditions. Sheets 21 and 22 are suitable for post -
developed, but supplement drainage divides with details that show runoff flow path. Include: overland
flow, shallow concentrated, and channel flow. (Pattern calculations after Methods in VESCH, 1992, Ch. 5,
Engineering Review Comments
Page 3 of 6
Engineering Calculations, p. V4 -V -7). T, estimates are unrealistic. Note: -see p. 3 /routing report: T,, sub -
catchment 2S (post) =12.0 min; Tc sub - catchment 7S (pre) =8.0 min. The pre - developed condition for the
entire site is pure forest; this best possible cover offers longer T, than post - developed conditions. With
construction of roads, loss of forest, pre - developed Tc must exceed post - developed Tc. Artificial flow paths
require revision. SWM basins and compliance calculations depend on accurate, reasonable estimate of Tc.
Review and present calculations for all pre- /post - developed time of concentrations (T,,).
11. No ED basin low flow orifice diameter may be < 3 ". Revise design. 3" min. diameter is established review
criteria: ref BMP design specification #15, 6.5, Conveyance and Overflow, Non - Clogging Low Flow
Orifice. Text reads, in part: "ED ponds with drainage areas of 10 acres or less, where small diameter pipes
are typical, are prone to chronic clogging by organic debris and sediment. Orifices less than 3 inches in
diameter may require extra attention during design to minimize the potential for clogging. Designers
should always look at upstream conditions to assess the potential for higher sediment and woody debris
loads." Nearly every adverse factor is present with proposed design: steep slopes (highly erodible), poor
hydrologic soils (highest runoff potential), woods /debris, drainage area < 10 Ac (`B'), and proposed 0.7"
and 1.0" diameter flow control orifices. Revise design to eliminate control orifice diameter < 3.0 ".
12. Furnish debris cages for flow control orifices.
13. Revise (or explain via narrative) how primary spillway riser, ED basin `B' is to be constructed. Proposed
design shows riser embedded 10' f below existing grade, 18.2' below proposed bottom of ED basin.
14. BMP Clearinzhouse, Appendix A, Earthen Embankment: Please review and adopt technical criteria. For
example: for embankment ht. >25', min. top width =15'. (Ref. Table A -1: Embankment Top Widths /p. 9.)
Revise accordingly. (Extended Detention `B' embankment ht. = 25.25')
15. Appendix A. Earthen Embankment /p.3 - reference Geotechnical Guidelines. Furnish Geotechnical report. -
Also, #14.
16. Ref Design Specification #I5, 6.3, Required Geotechnical Testing - furnish soil boring test results. -Also, #15.
17. ED Level 1 is appropriate if CDA is less than 10 acres. CDA, ED `A' =12.55 Ac. Level 2 is required.
Ref. Table 15.2, Extended Detention (ED) Pond Criteria when designing Level 2 ED.
18. Review and revise basin and forebay embankment widths, as necessary, per Appendix A. -Also, #14.
19. Review /revise spillway dimensions in routings, given 3:1 (or 4:1) side slopes that increase breadth broad -
crested rectangular weirs. For example, without increasing embankment width (using proposed widths),
weir breadths (HydroCAD) are: ED `A' = 20.25' (vs. 8.0'); Forebay Pool A =14.0' (vs. 4.0'); ED `B'
=22.0' (vs. 8.0'); Forebay Pool `B' =8.0' (vs. 4.0'). Revise widths as required; re -run models using
corrected weir breadth dimensions. Double check against 3:1/4:1 embankment side slopes.
20. Furnish emergency spillway design calculations -ref. BMP Clearinghouse, Appendix C.
21. Show emergency spillways to scale, plan view; for example: using profile view section view of emergency
spillway, ED `B', plan view width should =76'(±). Width shown =10.0'
22. Emergency spillway, ED `B' intrudes into stream buffer. Revise design to avoid stream buffer impact.
23. Consider mitigation for any unavoidable stream buffer impact.
24. Compare HydroCAD 100 -yr storm event peak Elev., Forebay `A' /`B' with profile MIN TOP ELEV. Each
forebay may be overtopped during the 100 -yr event; however, design may use Type II 24 -hr 100 -year
rainfall =9.1" (Albemarle County). Routings appear to use Type II 24 -hr 100 -year rainfall = 13.64 ".
Forebays must pass the 100 -yr storm without overtopping. Revise MIN. Top ELEV. if necessary.
25. Routing report (HydroCAD) /p. 11 - Revise ED `A' Inlet /Outlet Invert Elev, consistent with plans.
26. Routing report (HydroCAD) /p. 42 - Revise ED `B' Device #6 Invert, consistent with plans ( = 313.50').
27. ED `B' primary spillway barrel (841.£, 24" HDPE) slope = 0.36 %. Increase slope to 0.5% minimum.
28. Label Forebay Micro -pool slope (floor): 0 - 1.0%
29. Provide Micro -pool details specific to Level 1 (ED `B'), and Level 2 (ED `A') designs.
30. Forebay Micro -pool `A' depth =2.5'. Min. depth =4.0' Revise. -ref. Design Spec #15, 6.4, Pretreatment
Forebay, third bullet/p.6.
31. Revise ED basin emergency spillway side - slopes: 3:1 Max, per Appendix A, BMP Clearinghouse.
Engineering Review Comments
Page 4 of 6
32. In both ED profile views, please label spillway elev /length as Emergency spillway elev /length, for clarity.
33. Important: With forest nature of sites proposed for ED basins, furnish appropriate pre - treatment to trap
debris in storm runoff that reaches either ED basin without first passing through forebay Micro - pools.
34. Provide installation, inspection and maintenance Notes for Extended Detention similar to Notes provided
for Infiltration. -sheet 25.
35. Sheet 25 /Channel and Flood Protection table (VaRRM .xls) - revise target rainfall 1- 2- 10 -yr values. Use
3.5, 3.7, 5.6 -in, respectively (Albemarle County).
36. Request electronic copy of revised VaRRM .xls, (as review aid).
37. Detail/sheet 25 - Revise title: Connected roof drain Infiltration #1, Spec #8 does not exist in this
configuration -ref BMP Clearinghouse. Separate BMPs; adopt design specifications for practices.
(Especially note: roof drains may not be directly connected to infiltration practice /s. -Also #1).
38. Detail/sheet 25 - Average roof treatment Area =2,516 s.f.; this figure appears high, even unlikely unless
average dwelling size >5,000 s.f. Even if Ave. dwelling size >5,000s.f., explain how subdivision covenant
measures ensure that Ave. roof treatment Area = 2,516s.f
39. Minor - sheets 21, 22 - Eliminate reference to road plans in sheet title bar.
40. Provide ED BMP pretreatment for ditch line runoff, Osprey Drive to ED basin `A' (sheet 15). -Also, #33.
41. ED `A', `B' profiles reference Landscaping plan, but plan does not appear to be included with ESC /SWM
plan. Please consider planting plan requirements for ED (Spec. #15), and provide planting plan.
42. Show post-developedtree/wood line. -Also #2.
D. Erosion and Sediment Control Plan (ESOP - WPO201400095) -Items #1 -4/Max Green ( #5 -13 /Anderson)
Virginia Code §62.1- 44.15:55 requires the VESCP authority to approve or disapprove an ESOP. This plan is
disapproved, and the reasons are provided in the comments below. The erosion control plan content
requirements can be found in County Code section 17 -402.
1. The E &SC Plan does not appear to work and needs to be remade into a less than 13 page phased E &SC
plan. This project is not so big as to require a phasing plan. Please request a Thursday meeting if this
comment needs clarification.
2. Sediment trap and basin calculations and construction details are missing from submittal and could not be
reviewed at this time.
3. The Albemarle County Temporary Paved Construction entrance detail is missing from the plan.
4. Additional comments and /or conditions will be forthcoming after the E &SC plan has been reworked into a
more approvable submittal.
5. Sheets 3 -16: ESC Legend should include all symbols, with descriptions.
6. Combine sheets that show utility/mass grade ESC measures; combine sheets that show roadway /final grade
improvements, rather than 4 stages, each with 2 phases. The risk is confusion and non - compliance.
Inspectors may fail to appreciate level of (appropriate) control, may cite violations if stage -phase
schematics are not followed precisely. This level of detail may be very helpful for planning, and may
benefit the contractor, but it is problematic from a review /approved ESCP perspective. -Also #1.
7. Report Limits of Disturbance Acreage consistent with Registration Statement /SWPPP -show on plans.
8. If CWD are placed on the uphill side of diversions, locate sediment traps at intervals, down slope,
especially to protect stream buffers /Carroll Creek.
9. Note that hard angles in diversions or dikes are likely to fail (DV, CWD, DD); provide traps at these points.
10. Sediment Traps: provide design detail and dimensions for stone outlets, ST -1, ST -2, ST -3. OP4/9/19.
Engineering Review Comments
Page 5 of 6
11. Avoid 2:1 slopes when designing sediment traps on preserved or managed steep slopes (sheet 20).
12. Show TS /PS/MU/DC. Include these measures in Legend -Also #5.
13. Sheet 15: provide EC -2, EC -3 as appropriate, and furnish non - erodible storm runoff conveyance between
pipe outfall (triangle `4') and Forebay Micro -pool W.
E. VSMP: Mitigation Plan
- The mitigation plan requirements can be found in County Code section 17 -406.
1. Furnish mitigation plan /stream buffer impacts. Identify potential candidate stream buffer
mitigation areas on property, ideally, within 100' of stream. -Also, #22/ #23, Sec. C, above.
2. Furnish mitigation planting schedule- options, below:
1. option 1 - Mitigate through new plantings and permanent protection as given
below. New plantings must be in the stream buffer area. Applicant has choice of
planting one of the following:
a. For every 400 square foot unit or fraction thereof, plant one (I) canopy tree
measuring 1 V2" - 2" caliper or a large evergreen 6 feet in height, one (1)
understory tree measuring -Y4" - 1 V2" caliper or one evergreen 4 feet in height,
and one (I) .small shrub 15" - 18" in height.
b. For every acre or fraction thereof, plant 1,210 hardwood an&orpine seedlings
on approximately 6'X6' centers without tree tubes and mats.
c. For every acre or fraction thereof, plant 604 hardwood andlor pine seedlings
on approximately 8'X8' centers with tree tubes and mats.
2. Option 2 - Mitigate by preserving existing buffer where currently not required by
ordinance; i.e. preserve stream buffers on intermittent streams in the development
areas. Mitigation must be accomplished by permanent protections as given
below.
Permanent Protection for each of these options will be inclusion in the Thomas
Jefferson Soil and Water Conservation District (TJSWCD) Easement Program, or
recordation of a permanent maintenance agreement and escrow to run with the
land.
The VSMP permit application and all plans may be resubmitted for approval when all comments have been satisfactorily
addressed. For re- submittals please provide 2 copies of the complete permit package with a completed application form.
Engineering staff is available 2 -4 PM on Thursdays. A meeting is scheduled 8 -Jan, 3:30- 4:OOpm, to discuss this review.
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, county staff will need to enter project information in a DEQ database
for state application processing. DEQ will review the application information based on local VSMP authority
Engineering Review Comments
Page 6 of 6
approval. At this time, the DEQ portion of the application fees will need to be paid directly to the state. For fastest
processing, this is done electronically with the emails provided on the application. DEQ should notify applicants
with instructions on how to pay fees. When DEQ approves the application, they will issue a permit coverage letter.
This should be copied to the county.
After DEQ coverage is issued, via the coverage letter, the County can hold a pre - construction conference.
Applicants will need to complete the request for a pre - construction conference 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;
http : / /www. alb emarle. org/deptforms. asp? dep artment =c dengwp o
File: WP0201400095- Glenmore Sect K2C VSMP- 123014.doc