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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 /Chris Mulligan, Roudabush, Gale & Assoc, Inc
914 Monticello Road, Charlottesville, VA 22902, AGeoree(a),roudabush.com;
cmulligan(a)roudabush. com
Owner or rep.:
Glenmore Associates Limited Partnership, P.O. Box 7623
Charlottesville, VA 22906
Plan received date:
19 Nov 2014
(Rev. 1)
10 Feb 2015
Date of comments:
9 Dec 2014, ESCP
30 Dec 2014, VSMP
(Rev. 1)
26 Feb 2015
Reviewer:
Max Greene, ESCP
John Anderson, VSMP (9 Dec; 26 Jan 15)
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. 1 /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).
(Rev. 1) — Comment addressed. Applicant Response (Letter, 10 Feb 15): "At this time,
this will be the only parcel developed by the Piedmont Neighborhoods LLC."
b. Sec. 2 /NOTICE OF GENERAL PERMIT COVERAGE /Glenmore Subdivision — provide a copy of the
DEQ coverage letter (when obtained). (Rev. 1) — Comment acknowledged.
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 .xls, DA A, B, C) total 15.87 Ac. Please
revise narrative, as necessary, consistent with plans. —Ref additional SWM plan review
Engineering Review Comments
Page 2 of 8
comments, below. (Rev. 1) — Comment addressed. As follow -up, developer intends to
selectively remove /preserve trees (per discussion, 8 -Jan). Applicant: "The limits of
clearing and grading for the individual lots will be shown at the building permit phase to
reflect the actual footprint of the house selected by the home buyer and the relevant site
grading. As this is done with the building permit phase, the builder will be responsible
for that particular lot." Note: SWM /ESC regulations apply to individual lots within a
larger plan of development. A caution: encroachment beyond LOD may warrant
enforcement.
d. Sec. 4 /EROSION AND SEDIMENT CONTROL PLAN — provide a reduced I I x 17 copy of the latest
ESC plan (May wait until ESCP is approved/do not reference only). (Rev. 1) Comment
addressed. As follow -up: please do not print revised reduced -size plan sheets that may
change in response to request for ESCP /SWMP revisions until point of plan approval.
e. Sec. &POLLUTION PREVENTION PLAN — A. Provide a reduced I I x 17 copy of sheet 26
Addressed ; E. Identify persons responsible for pollution prevention practices; F.
Complete (Response and Reporting Practices *) As follow -up: complete Emergency 24-
hr contact section; G. Complete (Pollution Prevention Awareness *) (Rev. 1) Comment
partially addressed: Response: "At this time, the project does not have a general
contractor who will be responsible for the pollution prevention practices." RGA
personnel may be listed for the time being. Qualified personnel must be listed by name.
f. Sec. 8 /QUALIFIED PERSONNEL — List* (Rev. 1) Comment partially addressed: Response:
"At this time, it is unknown who will be in charge of the SWPPP inspections. The
SWPPP document will be updated with their contact information when it becomes
available." RGA personnel may be listed for the time being. Qualified personnel must
be listed by name.
g. Sec. 10 /DELEGATION OF AUTHORITY — Complete, if authority delegated. (Rev. 1) Comment
addressed. Response: Owner has not delegated authority to any party; will be completed
as applicable.
h. Sec. 11 /GENERAL PERMIT COPY — Provide /Attach 22 -p. 2014 General VPDES permit. (Rev.
1) Comment addressed.
i. Sec. 12 /INSPECTION LOGS — Provide* (Rev. 1) Comment addressed.
( * 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. (Rev. 1) Comment addressed.
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
htW: / /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/DEO %20BMP %20 Spec %2ONo %208_ INFILTRATION_Fi
nal %20Draft_v 1- 9_03012011.pdf
Revise BMP connected roof drain - infiltration design. Provide pretreatment, per BMP specification. (Rev.
1) Comment partially addressed. As follow -up: Locate rooftop disconnections on plan sheets; six
proposed. —Also: ref email, Tue 2/24/2015 6:54 AM
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
Engineering Review Comments
Page 3 of 8
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. (Rev. 1) Comment partially
addressed. Response: "Restrictive Covenants shall be provided to protect and maintain both Open Space
and maintenance with the easements." —Also, email: Tue 2/24/2015 6:54 AM).
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. (Rev. 1) Comment partially addressed. As follow -up: Revise DA -B drainage
divide. Divide lies closer to western edge of Waterside Way cul -de -sac; ref. Osprey Drive drainage divide
which lies close to the cul -de -sac, and is more nearly accurate (ref. 2/24 email).
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. (Rev. 1) Comment partially addressed. As follow -up:
Restore format of Energy Balance equation found at 9VAC25- 870 -66 to calculations shown on plan sheet
20. Compare with initial plan sheet 25.
5. Energy Balance, DA `A': compare HydroCAD /p. 6 inflow depth >0.16" with Rv Pre -Dev. = 0.09 ". Reconcile.
(Rev. 1) Comment withdrawn: routings report substantially revised.
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) (Rev. 1) Addressed.
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 ". (Rev. 1) Comment partially
addressed (via revised routings). As follow -up: restore initial routing design which models project as two
separate, major drainage divides (DA -A, DA -B). Revised routings that use a pre - developed 36.70 acre site,
2000' flow length, and Tc =35.9 min is unacceptable. Use RVDweroped (in) with runoff reduction, Channel &
Flood Protection tab, VRRM .xls (e -mail attachment, 13 -Feb). Pending further design/routing revision, RV
1 -yr storm values are: DA -A (CN =81) 1.31in; DA -B, 1.34in; DA -C, 2.68in.
RV = 1.25in (sheet 20) is unacceptable as it does not match VRRM .xls.
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'. (Rev. 1) Withdrawn: routings report
substantially revised.
9. Energy Balance, DA `A': compare HydroCAD report/p. 6, 1.68 cfs with (sheet 25) 1.33 cfs. Reconcile.
(Rev. 1) Withdrawn: routings report substantially revised.
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 Calculations, p. V4 -V -7). Te estimates are [Appear] unrealistic. Note: -see p. 3 /routing report: Te,
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 Te than post - developed conditions. With
construction of roads, loss of forest, pre - developed Te must exceed post - developed Te. 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 (Te). (Rev. 1)
Narrative response [TJ does not adequately address comment: Please show (runoff) flow paths, sheets
16, 17. Provide Te calculations. Ref VESCH.
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
Engineering Review Comments
Page 4 of 8
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 ". (Rev.
1) Comment not addressed. Revised design further reduces control orifice diameter. Topic discussed on
8 -Jan, but proposal for diameter <3.0" was not accepted. We regret any misunderstanding.
12. Furnish debris cages for flow control orifices. (Rev. 1) Comment insufficiently addressed. Provide
debris cage suitable for 3" (or larger) DIA 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. (Rev.
1) Comment partially addressed. As follow -up: provide detail for riser structure concrete bases (ref. VA
DEQ Stormwater Design Specification No. 15, sec.6.5, p. 7, Anti - flotation).
14. BMP Clearinghouse, 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') (Rev. 1) Comment partially
addressed. ED -A. Forebay embankment top width =8.0, if 7.5' high. ED -B, Forebay (micro -pool)
embankment top width =10.0, if 16' high. (Ref Table A -1). "The height of an earthen embankment is the
vertical distance from the natural bed of the stream or watercourse, measured at the downstream toe of the
embankment, to the top of the embankment." (Appendix A, pg. 2)
15. Appendix A. Earthen Embankment/
p.3 - reference Geotechnical Guidelines. Furnish Geotechnical report. -
Also, #14.
16. Ref Design Specification #15, 6.3, Required Geotechnical Testing - furnish soil boring test results. -Also, #15.
(Rev. 1) Comment partially addressed: We have infiltration rate data (> 4in/hr), but lack sufficient
geotechnical information, per spec [If submitted, please notify ACCD; possible was misplaced]:
6.3. Required Geatechnical Testing
Soil borings should be taken below the proposed embankment, in the vicinity of the proposed
outlet area, and in at least two locations within the proposed ED pond treatment area. Soil boring
data is needed to (1) determine the physical characteristics of the excavated material, (2)
determine its adequacy for use as structural fill or spoil, (3) provide data for structural designs of
the outlet works (e.g., bearing capacity and buoyancy), (4) determine compaction/composition
needs for the embankment, (5) determine the depth to groundwater and bedrock and (6) evaluate
potential infiltration losses (and the potential need for a liner).
As follow -up: Design ED -A embankment core; ref. impermeable clay core design of ED -B embankment.
Show phreatic lines. Use conservative approach with phreatic line starting at the 10 -yr design storm water
surface elevation (Ref. Embankment Zoning and Seepage, Appendix A, Earthen Embankment, n. 6 -7). Design
and show internal features required for each embankment (cutoff trench/drains, etc).
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. (Rev. 1) Addressed.
18. Review and revise basin and forebay embankment widths, as necessary, per Appendix A. -Also, #14.
(Rev. 1) Comment partially addressed. -Also, see #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. (Rev. 1)
Engineering Review Comments
Page 5 of 8
Comment partially addressed. If revise forebay embankment top width, using slope information, then
ED -A Forebay weir breadth =18'; ED -B Forebay weir breadth =13'. Revise design/routings.
20. Furnish emergency spillway design calculations —ref. BMP Clearinghouse, Appendix C. (Rev. 1)
Withdrawn. Applicant response: "Since they [emergency spillways] are not a requirement to pass any
regulated storm events, they are provided simply as a relief mechanism." Also, response to #19: "Please
keep in mind that the Emergency Spillways are such that the standard storms are conveyed via the riser. In
other words, they are an emergency pass - through only and the flows that they pass do not actually affect
the basin design."
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' (f). Width shown =10.0' (Rev. 1) Addressed.
22. Emergency spillway, ED `B' intrudes into stream buffer. Revise design to avoid stream buffer impact.
(Rev. 1) Addressed. Redesign provides additional separation between outfall and stream buffer.
23. Consider mitigation for any unavoidable stream buffer impact. (Rev. 1) Addressed. No mitigation
required since SWM facilities removed from stream buffer.
24. Compare HydroCAD 100 -yr storm event peak Elev., Forebay `A' /`B' with profile Mite 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 Mite. Top ELEv. if necessary. (Rev. 1)
Addressed.
25. Routing report (HydroCAD) /p. 11 — Revise ED `A' Inlet /Outlet Invert Elev, consistent with plans. (Rev. 1)
Withdrawn: routings report substantially revised.
26. Routing report (HydroCAD) /p. 42 — Revise ED `B' Device #6 Invert, consistent with plans ( = 313.50').
(Rev. 1) Withdrawn: routings report substantially revised.
27. ED `B' primary spillway barrel (841.£, 24" HDPE) slope = 0.36 %. Increase slope to 0.5% minimum.
(Rev. 1) Addressed.
28. Label Forebay Micro -pool slope (floor): 0 — 1.0 %. (Rev. 1) Comment not addressed.
29. Provide Micro -pool details specific to Level 1 (ED `B'), and Level 2 (ED `A') designs. (Rev. 1) Comment
partially addressed; provide aquatic bench details, for example.
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. (Rev. 1) Addressed.
31. Revise ED basin emergency spillway side - slopes: 3:1 Max, per Appendix A, BMP Clearinghouse. (Rev. 1)
Addressed.
32. In both ED profile views, please label spillway elev /length as Emergency spillway elev /length, for clarity.
(Rev. 1) Addressed —reff, plan view dimensions.
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.
(Rev. 1) Addressed. "Pre- treatment for debris shall consist of a trash- rack/AV device for each plunge
Pool."
34. Provide installation, inspection and maintenance Notes for Extended Detention similar to Notes provided
for Infiltration. —sheet 25. (Rev. 1) Comment partially addressed. Provide Extended Detention BMP
installation notes.
35. Sheet 25 /Channel and Flood Protection table (VaRRM .xls) — revise target rainfall 1- 2- 10 -yr values. Use
34, 3.04, 3.7, 5.6 -in, respectively (Albemarle County). (Rev. 1) Addressed — thanks for correcting review
error.
36. Request electronic copy of revised VaRRM .xls, (as review aid). (Rev. 1) Addressed. Provided.
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). (Rev. 1)
Addressed — disconnected roof leaders only.
Engineering Review Comments
Page 6 of 8
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 >S,OOOs.f, explain how subdivision covenant
measures ensure that Ave. roof treatment Area = 2,516s.f. (Rev. 1) Addressed. "The required rooftop
treatment area is now 6,000 S.F. in total, requiring 6 rooftop disconnections."
39. Minor — sheets 21, 22 — Eliminate reference to road plans in sheet title bar. (Rev. 1) Addressed.
40. Provide ED BMP pretreatment for ditch line runoff, Osprey Drive to ED basin `A' (sheet 15). —Also, #33.
(Rev. 1) Addressed using riprap OP.
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. (Rev. 1)
Comment not addressed.
42. Show post-developed tree /wood line. —Also #2. (Rev. 1) Addressed.
New
1. Check T, Calculations, ED -A, ED -B. Using Rv = 1.31in (DA -A), 1.34in (DA -B) [see item # C.7.], and DA-
A CDA =12.55 Ac, DA-13 CDA =83 Ac [VRRM .xls, DA tabs], plan review yields ED -A Tv = 74,599cf
(compare with 14,704cf /sheet 18), and ED -B Tv = 40,373cf (compare with 7,714cf /sheet 19). Revise
calculation and design of extended detention ponds (Level 1, Level 2) if necessary.
Table 15.2. Extended Defe"Han Pond Criteria
Level 1 Des ig n 1111:4• TP:15• TN: 10)
Level 2 Desi n (RR: 15; TP:15• TN: 10
T„ = [(1.0) (Rv) (A)] 112 —the volume reduced by
T„ = ((125) (R,,) (A)] 112 —the volume reduced
an upstream BMP
by an upstream BMP
A min umum of 15% of the Tv in the permanent
A minurnum of 40% of Tv in the permanent pool
pool foreba , micro pool)
(fore bay, micro pool, or deep pool, or wetlands
2. Provide calculations to ensure minimum Tv is provided in permanent pool (forebay, micropool, deep pool).
3. Max. vertical Tv ED limit is 4 feet (Table 15.2 /spec): ED -A vertical = 6.11'. Revise.
4. Minor: Revise ED -B, Forebay micro -pool 48" riser Tor ELEV. Elev. = 325.81'.
D. Erosion and Sediment Control Plan (ESCP - WPO201400095) —Items #14/Max Green ( #5 -13 /Anderson)
Virginia Code §62.1- 44.15:55 requires the VESCP authority to approve or disapprove an ESCP. 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.
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. (Rev. 1) Comment response: "[The developer] has maintained his desire to
save as many of the existing trees in the open space as possible. I also took into account the County
Engineer's concern that a multi - phased plan would be hard for the contractor and inspectors to follow."
ESCP remains problematic (number of plan sheets has increased). Comment requires discussion, decision
on part of County /Applicant. —Also, item A.2.c. (SWPPP) As follow -up: provide a single plan sheet that
shows areas that will not be disturbed by any stage or phase of activity: Areas beyond all LOD. Please
indicate clearly all areas not to be disturbed on a single plan sheet.
2. Sediment trap and basin calculations and construction details are missing from submittal and could not be
reviewed at this time. (Rev. 1) Comment partially addressed. Provide volume calculations for each ST.
3. The Albemarle County Temporary Paved Construction entrance detail is missing from the plan. (Rev. 1)
Addressed.
4. Additional comments and /or conditions will be forthcoming after the E &SC plan has been reworked into a
more approvable submittal. (Rev. 1) Acknowledged.
5. Sheets 3 -16: ESC Legend should include all symbols, with descriptions. (Rev. 1) Addressed.
Engineering Review Comments
Page 7 of 8
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. (Rev. 1)
Comment response /plan revisions require discussion. -Also, item D. # 1.
7. Report Limits of Disturbance Acreage consistent with Registration Statement /SWPPP -show on plans.
(Rev. 1) Addressed.
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. (Rev. 1) Comment partially addressed. Provide traps
between utility installation trenching and Carroll Creek.
9. Note that hard angles in diversions or dikes are likely to fail (DV, CWD, DD); provide traps at these points.
(Rev. 1) Addressed.
10. Sediment Traps: provide design detail and dimensions for stone outlets, ST -1, ST -2, ST -3. OP4/9/19.
(Rev. 1) Addressed.
11. Avoid 2:1 slopes when designing sediment traps on preserved or managed steep slopes (sheet 20). (Rev. 1)
Addressed. "Blanket matting has been specified to cover any slopes that exceed 3:1." As follow -0:
please include Note to this effect on each ESC plan -view plan sheet.
12. Show TS /PS /MU/DC. Include these measures in Legend -Also #5. (Rev. 1) Addressed.
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. (Rev. 1) Addressed.
New
1. Include plan sheet & sequence of construction notes directing Contractor to flag or mark all Areas outside
all LOD: Areas not to be disturbed (paint, flagging, stakes, etc).
2. Show ST -1. (Various sheets)
3. Show check dams, plan -view. Revise legend to include check dams.
4. Show sediment trap stone weir outfalls, ST -3, -4, -5, -6 (sheet 8B).
5. Furnish plan sheet notes to prevent traffic using trap embankments as roads (ST -4, for example).
6. ST -2, ST -4 exceed wet storage maximum depth: 4'. Revise design.
7. Provide dimensions for ST floors, plan -view.
8. Provide diversion/s to route runoff to ST -5.
9. Show storm pipe end sections, ST -2, ST -5.
10. Renumber sediment trap #3, sheet 8B.
11. Turn on critical slopes layer, sheet 17.
12. Recalculate DA -B (Ac.). Revise routings, design, etc.
13. Revise conflicting contours: SWM Facility ED -B access and Osprey Dr. cul -de -sac (sheets 8B, 9, 9B, etc).
14. Relocate either storm pipes or sediment traps 4 and 5. The intersection of conveyance and traps does not
work. Traps, once built, must be maintained and not disturbed.
15. Consider Access, sheet 3A: provide access /show LOD for constructing southernmost utility corridor.
16. Revise Zone A floodplain boundary at CC 4 -1. Review boundary generally. Boundary appears to fall at
different elevations either side of Carroll Creek. A flood insurance rate study exists, and is available, for
Rivanna River not far distant from this site, which may lend additional detail.
17. Slopes > 2:1 require "landscaping vegetation hardier than grass which will not require mowing" [ACDSM
8.A.2.] Propose permanent stabilization (plant species); this includes all critical slopes, by default.
18. Sheet 11 - Transfer sequence of construction notes (sheet 11) to plan sheets in blocks, ending each block
with text that explains that "measures must be in place and operational prior to beginning next stage."
19. Delete ESC Min Std. references to infiltration areas /infiltration pits, sheet 14.
Engineering Review Comments
Page 8 of 8
20. Sheet 11 — Renumber sequence of construction Notes 44/45 (2 of each).
21. Title sheet, minor: revise index, sheet 10, to read "Phase 2"
22. Delete curve table, top of sheets 3, 6, 7A, 9, etc.
E. VSMP: Mitigation Plan — (Rev. 1) Addressed. NA/see items (C.) # 22, 23
— 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 [image deleted]:
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 5 -Mar, 3:00- 4:00pm, 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
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;
httn: / /www. alb emarle. ore /dentforms. asn? den artment--c den ewn o
File: WP0201400095- Glenmore Sect K2C VSMP- 022615rev