HomeMy WebLinkAboutWPO201000056 Review Comments WPO VSMP 2021-02-12COUNTY 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 title: Ashcroft — Phase III
Project file number: WPO201000056/WPO200700053 (Amendment)
Plan preparer:
Dominion Engineering [dgreene@roudabush.com]
Owner or rep.:
Richard L. Beyer [rick@beyerhomes.com]
Plan received date:
Jan 30, 2018
Jan 7, 2019
May 17, 2019
Dec 29, 2020
Date of comments:
March 7, 2018
Feb 15, 2019 (Rev. 1)
June 27, 2019 (Rev. 2)
Feb 12, 2021 (Rev. 3)
Reviewer:
David James (ext. 3273)
County Code section 17-410 and Virginia Code §62.1-44.15:34 requires 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.
Amendments (General):
1. The approved plans must be included in the plan set, with the specific areas of
amendment clearly outlined by bubbling or circling. The approved plans must not
otherwise be altered.
(Rev.1) Addressed.
2. (Rev.1) Submit the E&SC Plan for review. Comments under section E below have
not been addressed.
(Rev.2) Addressed.
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 —Update the R.S. to include (1) a phone# & (7) County of Albemarle as
MS4 operator.
(Rev.1) Addressed.
2. Provide an overall map `exhibit sheet' insert of the PPP showing the potential sources of
stormwater pollution generating activities (location & type).
(Rev.1) Not addressed.
(Rev.2/3) Partially addressed. See B.1. comment.
3. Provide any additional locations on PPP & ESC plan for support activities (17-405A(5)a).
(Rev.1) Not addressed.
(Rev.2/3) Partially addressed. See B.1. comment.
4. (Rev.3) Submit revised Registration Statement; please:
Engineering Review Comments
Page 2 of 11
a. Complete offsite (fill) export section.
b. Ensure construction dates are accurate.
c. Ensure form is signed and dated.
d. Ensure MS4 data is accurate.
5. (Rev.3) Appx. A sheets; appears that all the back sides were printed upside down.
B. Pollution Prevention Plan (PPP)
The PPP content requirements can be found in County Code section 17-404.
1. Submit `exhibit sheet' for review.
(Rev.1) Not addressed.
(Rev.2) Partially addressed. It needs to be updated to show any proposed clearing/grading
activities, paving operations, landscaping operations, E&S controls, staging, stockpile, borrow,
fueling, waste disposal, vehicle/equipment washing, concrete washout locations. Also, show
locations where concentrated stormwater discharges.
(Rev.3) Partially addressed. Provide 1 or 2 full-sized sheets to show the entire disturbed
area. Show/Indicate concentrated stormwater discharge points.
C. Stormwater Management Plan (SWMP)
VSMP Regulation 9VAC25-870-108 requires the VSMP authority to approve or disapprove a
SWMP. This plan is not approved, and the reasons are provided in the comments below. The
stormwater management plan content requirements can be found in County Code section 17-403.
1. Provide any state permits authorizing disturbance of the streams and wetland areas. Letter
provided on Sheet E2 is a letter of determination, not a permit to impact wetlands or waters of the
State.
(Rev.1) Acknowledged. Show WPO buffer.
(Rev.2) Addressed.
2. According to SWM narrative you plan to meet energy balance by using a biofilter, but the
amended plan proposes to remove all biofilters. Please clarify.
(Rev.1) Addressed.
3. It appears that the existing drainage area of 175 ac. to SWM-1 according to the plans is
smaller than what I assessed. Please confirm and correct the DA size accordingly.
(Rev.1) Addressed.
4. Show how you determined the phosphorus removal rates (water quality under Part 11 C).
(Rev.1) Addressed.
5. Remove approval block from cover sheet.
(Rev.1) Addressed.
6. Show direction of stormwater flow and approximate slopes after grading operations (17-
405A(5)a).
(Rev.1) Comment still valid.
Response: The direction of stormwater flow and approximate slopes after grading have been
shown on sheet 5.
(Rev.2) The note stating that all slopes are 4:1 or 3:1 appears to be inaccurate. See comment
E.10 below.
(Rev.3) Currently ddressed.
7. Show SWM Facility & access easement. Show drainage easements & widths.
(Rev.1) Currently addressed.
(Rev.2) Include vegetative buffer within SWM facility easements.
(Rev.3) Show access easement for SWM-I.
8. Stormwater maintenance agreement & SWM bond required prior to issuing grading permit.
Engineering Review Comments
Page 3 of 11
(Rev.1) SWM bond required prior to issuing grading permit.
(Rev.2/3) Comments still apply.
9. Provide mitigation plan for WPO buffer disturbance.
(Rev.l) Addressed.
10. SWM facility easement plat and deed must be submitted, reviewed, approved and recorded prior
to VSMP plan approval. If these were already recorded, please provide a copy of the plat and
deed.
(Rev.1/2/3) Comment still valid.
11. (Rev.1) Sheet 3/4 -
a. Show WPO buffer. (Rev.2) Addressed.
b. Show sediment forebays in the details. (Rev.2) Addressed.
c. Design adequate outfall protection from the principal spillway to receiving channel;
Designed to control the expected weir flow and velocity. (Rev.2) Label the energy
dissipater at the outfall points. It's hard to see the contours there (recommend
lightening the hatching pattern). (Rev.3) Addressed.
d. Extend concrete armoring to toe of dam. (Rev.2) Use grouted riprap to toe. (Rev.3)
Addressed.
e. Veg. emergency spillway should not be located on any portion of the embankment fill.
Armored spillway may be provided. (SWM HB, Min. Standard 3.03) (Rev.2) Correct
details on sheet 3, remove `grassed' label and leave `emergency spillway'. (Rev.3)
Addressed.
f. There should be a defined & adequate receiving channel from the spillways. (Rev.2)
Addressed.
g. Show minimum 20' wide vegetative buffer strip, as measured from the maximum WSE.
(Rev.2) Show it as 20' from the 100-yr elevation. Include this buffer width in SWM
facility easements. (Rev.3) Currently addressed for SWM-1, not sure about SWM-2.
h. Basin should be 20' from any structure or property line, and 100' from any septic
tank/drainfield. (Rev.2) Currently addressed. Will need to show any proposed
drainfields, lot lines for SUB plan, Dept. of health to review. (Rev.3) Acknowledged.
i. Retention basin should be a 50' (min) from any steep slopes. Alternatively, a
geotechnical report must address the potential impact the basin will have constructed near
such slope in accordance with SWM HB, Min. St'd 3.01. (Rev.2) Not addressed. Steep
slopes (not critical slopes) defined as greater than 15%. (SWM HB, Min St'd 3.06)
(Rev.3) Provide letter from Geotech certifying built basin will not impact steep slopes
and if so what's proposed will remedy / mitigate the impact. Pond embankment reports
will be required prior to release of this facility. Notify ESC inspector on the start of
embankment construction. A geotech engineer should be present during and after
construction to monitor, report and verify stability and compaction of dam.
j. An aquatic bench should be provided if the basin's surface area exceeds 20,000 sf. (SWM
HB Min. St'd 3.06) (Rev.2) Provide landscaping plan requirements for the aquatic
benches. (SMW HB, Min. St'd 3.05) (Rev.3) Acknowledged.
k. The embankment cutoff trench should be excavated a min. 4' in to suitable material.
(Rev.2) Addressed.
1. Trees & shrubbery should not be planted on the embankment & in area extending
25' beyond toe of dam. (Rev.2) Addressed.
m. The forebays should be accessible by maintenance equipment. Provide access to
other forebay. (Rev.2) Addressed.
n. Provide trash rack detail. (Rev.2) Addressed.
o. Verify if the invert of the barrel is 725.5' and not 726'. 725.5' shown in plan, 726' in
calcs. Provide anti -seep collar or filter diaphragm for barrel. Joints should be made
watertight. (SWM HB, Min. St'd 3.02) (Rev.2) Addressed.
Engineering Review Comments
Page 4 of 11
p. SWM-2 - Show 12" orifice. Show emergency spillway cross-section detail. (Rev. 2)
Addressed.
q. Provide posted warning signs around SWM-1. (SWM HB Min St'd 3.06) (Rev.3)
Revise, provide for SWM-1 & 2 at each access point before the forebays.
12. (Rev.1) The channels leading from SWM basins will have to meet channel / flood protection
to your limits of analysis.
(Rev.2) Addressed.
13. (Rev.1) A geotechnical engineer or technician should be on site during embankment
construction to monitor and report proper installation/construction.
(Rev.2) Addressed.
14. (Rev.1) Provide narrative for the maintenance requirements of the proposed SWM
facilities.
(Rev.2) Addressed.
15. (Rev.1) All culverts/conveyances shall discharge concentrated runoff to a natural channel or
adequate channel, or SWM facility (i.e. culverts on sheet 3 do not).
(Rev.2) You must show each conveyance channel from every outfall point meets adequate
channel (2410-yr design) to your limits of analysis (VAESC HB, Ch.S, V-122).
(Rev.3) Show level spreader locations on the SWM plan.
16. (Rev.1) Sheet 5 -
a. You're showing undetained areas in your disturbance - DA-Y and DA-B1. Provide
stormwater management for the runoff in those areas. Show how those areas will meet
water quantity req.
(Rev.2) Show adequacy of outfall channels (2-yr/10-yr channel analysis) for each
outfall point to your limits of analysis.
(Rev.3) Acknowledged.
b. Label your Tc flow path.
(Rev.2) Currently addressed.
c. (Rev.2) Why is the pre-dev Tc (25.3 min) much lower than the approved plans pre-dev
Tc (44.26 min)? Show computation of Tc using Worksheet 3 (TR-55)' for DA-A, DA-B,
DA-M & DA-Q & determination of Q.
(Rev.3) I didn't find the worksheet, please provide. Need to verify any changes from
previously approved design.
17. (Rev.1) Calc. packet -
a. Your DA of 142.28ac should match the plan 142.8ac going to SWM-L
(Rev.2) Addressed.
b. According to Hyd. No. 10 the 10 yr peak discharge is 86.71cfs. What is the velocity
from the spillway?
(Rev.2) Addressed with energy dissipation at outfall prior to entering stream.
c. Show the outflow (discharge/velocity for the 1,2,10,100yr) report for the pond orifice and
weir controls.
i. (Rev.2) Provide report of the outflows from the controls (velocity & discharge
rate). (Rev.3) What is the velocity out of each barrel? Provide minimum rip -
rap size. Extend rip -rap to top of stream embankment.
ii. (Rev.2) SN) ' report - Show staging starting from bottom elev. 656'.
(Rev.3) Acknowledged.
iii. (Rev.3) Correct typo, invert elev. should be 658.00'.
18. (Rev.3) Revise plan title to include `Amendment #1 to WPO200700053 (ESC),
WPO201000056 (SWM)'.
19. (Rev.3) Include Construction Record Drawing (As -built) for VSMP on the plans; link:
https://www.albemarle.org/Home/ShowDocument?id=3381.
20. (Rev.3) Per Cale. report and 9VAC25-870-48, since there is a proposed increase in the
Engineering Review Comments
Page 5 of 11
proposed volume or rate of runoff from both SWM1, and SWM2, design criteria IIB
applies to this project, not criteria IIC. This means requirements at 9VAC25-870-65 (water
quality) and 9VAC25-870-66 (water quantity) apply. This has global implications for
design; please ensure revised Amendment submittal conforms with applicable county code
and VAC code requirements, vis-a-vis stormwater management, including BMP
clearinghouse design, construction, construction inspection, and subsurface exploratory
investigation requirements. Additional comments are possible.
21. (Rev.3) Sheet S-6 and Cale. report indicate biofilter 3, if removed from the plan, will
increase `the amount of phosphorus leaving this point,' by 0.08 lb. In this instance, the
proposed Amendment is ineligible for review as a `Grandfathered' design criteria IIC
project, and must be designed and evaluated under criteria IIB. Note: it appears that BF-1
and BF-2 may be removed, since these biofilters are upslope of SWM-2, and Calc. packet
indicates that the post -developed proposed phosphorus removal rate increases over the
approved plan if SWM-2 phosphorus removal rate increases from 50% to 65%.
22. (Rev.3) Please see Cale. report SWM-1, SWM-2 Q2-yr, Q10-yr approved vs. proposed peak
discharge rates; these indicate a volumetric (cfs) increase.
23. (Rev.3) Calc. report, SWM-1: Ensure that both approved and revised DA are identical -
they differ.
24. (Rev.3) Calc. report, p. 2, Water Quantity: Revise this sentence for clarity: `The increase in
volume for SWM-2 has decreased the peak for the 2-yr and 10-yr storm event compared to
the approved plan.' The sentence is confusing (increase -decrease), also inconsistent with
table values, item 5., above.
25. (Rev.3) Calc. report, p. 2, Water Quality:
a. Sheet 24 shows an aquatic bench for SWM-2. Sheet 23 appears to indicate an
aquatic bench for SWM-I. If so, label SWM-I aquatic bench.
b. Revise text at center of p. 2 of report to clarify SWM-1 is to receive an aquatic
bench.
26. (Rev.3) Revise culvert A needs to be of a different type to meet Sec. 17-604 C.La
requirement.
27. (Rev.3) Revise, currently the other requirements for Stream crossings are not being met,
such as, disturbance minimized & bank stabilization. (Sec. 17-604 C)
28. (Rev.3) Sheet 24 - Label the 2-,10-,100-yr design WSE on the cross-section.
29. (Rev.3) Level spreaders (ELS)-
a. ELS do not appear to be sized correctly. Area is wooded, correct? Existing land
cover is forest (GIS). The length requirement is 40' per cfs.
b. Provide energy dissipator or forebay. Show detail of each. Designed at flat grade
before ELS.
• A forebay should have a minimum depth of 12 inches (Figure 2.4). The forebay is
sized such that the surface area is a minimum of 0.2% of the contributing
impervious area.
c. Provide that the first 10' from lip is less than 2% grade.
30. (Rev.3) Sheets 18, 19 are ESC sheets, yet present graphic design information for SWM-2.
Relocate any SWM graphic, table, text, or details from ESC plan sheets to SWM plan
sheets.
31. (Rev.3) Calc. booklet requires revision to demonstrate compliance with 9VAC25-870-65.
32. (Rev.3) Calc. booklet requires revision to demonstrate compliance with 9VAC25-870-
66.B.3., and other provisions.
33. (Rev.3) Provide VaRRM xls for New Development. Include in Cale. report. Include
relevant .xis information on the plan; i.e. site, WQ compliance, runoff volume and CN, and
summary tabs, in their entirety.
Engineering Review Comments
Page 6 of 11
34. (Rev.3) Provide Note with each sheet of plan that presents SWM (design or narrative) that
includes this statement from county code: "18-4.3.3.C.4. - Surface water diversions. Surface
water shall be diverted from the face of all cut or fill slopes or both, using diversions,
ditches, and swales, or conveyed downslope by usin¢ a designed structure. The face of the
slope shall not be subject to any concentrated flows of surface water such as from natural
drainage ways, graded swales, downspouts, or similar conveyances." This mandatory note
shall guide final acceptance, and may influence builder, developer, owner, inspector
decisions throughout construction, into post -construction. At Cascadia subdivision,
Albemarle has struggled for several years to remediate erosion across constructed slopes
directly attributable to uncontrolled concentrated roof leader line discharge to high, steep,
constructed fill slopes. Albemarle intends to avoid this circumstance, wherever possible.
35. (Rev.3) Across SWM plan sheets, clearly label SWM-1, SWM-2 in every view.
36. (Rev.3) Sheet 12 - Provide deed bk.-pg. ref. to easement plat that shows SWM facility access
to SWM-1. Engineering needs to confirm access easement is in place for this SWM facility.
37. (Rev.3) Provide deed bk.-pg. ref. to SWM-1, SWM-2 facility easements.
38. (Rev.3) Provide deed bk.-pg. ref. to SWM Facility Maintenance Agreement for Ashcroft,
Phase III.
39. (Rev.3) SWM facilities (with this Amendment) are disallowed by ordinance at proposed
locations within GIS (100') stream buffer layer; please revise design accordingly.
40. (Rev.3) Provide SWM-1, SWM-2 riser standpipe base buoyancy calculations.
D. Mitigation Plan (MP)
The mitigation plan requirements can be found in County Code Chapter 17-406.
1. Submit plan & fee for review (17-208).
(Rev.1) Addressed.
2. (Rev.1) Must provide mitigation elsewhere in the stream buffer to meet the 2:1 requirement.
Identify other areas in the buffer where mitigation (restoration or reclamation) can be applied.
Response: Mitigation has been provided to the maximum extent possible.
(Rev.2) Conduct a survey to identify other possible mitigation areas on the property in the buffer
to meet this requirement.
(Rev.3) Not addressed. Per `Mitigation Plan' def. ".../EJncroachments into a stream buffer
will be mitigated through runoff treatment, revegetadon, the addition of extra buffer areas, or
other appropriate best managementpractices. " 117-205, p. 17-3) If not able to provide
required mitigation by revegetation you will provide mitigation though the other available
options.
3. (Rev.1) Concentrated discharges are to be treated or extended to adequate channels to preserve
buffers.
(Rev.2) Determination of adequate channels from outfalls to be included with next review.
(Rev.3 Acknowledged. Extend to stream top of embankment or adequate channel.
4. (Rev.3) Sheet 29-31- Revise, areas shown not reflective of disturbance. Your ultimate
Limits of Disturbance in the 100' stream buffer defines the impact area. Impact Area B & C
appears to outside your LOD.
5. (Rev.3) Native riparian vegetation cover shall be established and native vegetation shall be
preserved in the buffer. {17-601)
6. (Rev.3) Locate E&SC measures outside of buffer to max extent where feasible. {17-603)
E. Erosion and Sediment Control Plan (ESCP)
Engineering Review Comments
Page 7 of 11
Virginia Code §62.1-44.15:55 requires the VESCP authority to approve or disapprove an ESCP.
This plan is not approved, 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. Remove approval block from cover sheet.
(Rev.2) Addressed.
2. Provide date & source of topographic information: All topography should be at least
visually field verified by the designer within the last year.
(Rev.2) Addressed.
3. Show WPO buffer limits; 100' from stream or edge of wetland.
(Rev.2) Addressed.
4. Show all steep slopes (typically shaded). Existing critical slopes are not to be disturbed, unless a
waiver or exemption has been granted for the disturbance (18-4.2, 14-304).
Response: Steep slopes have been shown. The project is exempt from the critical slopes
ordinance.
(Rev.2) Partially addressed. Refer to Sect 17-405 A.6. (Rev.3) Acknowledged.
5. Show any existing easements with deed book references. -Meadow Crossing Trail 50' Private
Access Easement
(Rev.2) Not addressed.
(Rev.3) Acknowledged; an easement plat will need to be submitted & recorded prior to
Road plan approval.
6. Show construction staging, parking area(s).
(Rev.2) Addressed.
7. Adjust the LOD to encompass all disturbances, entrances (i.e. Lego Road intersection - Sta.
10+00 to Sta. 15+00), areas where sediment laden runoff will cross, and any construction
related activities (e.g. Sheet E7 - grading shown outside LOD).
(Rev.2) Currently addressed.
8. Indicate areas already disturbed with constructed fill depth or cut noted. The amended plan
shows that the grading for the road entranceway from intersection of Lego Road to Sta.
15+00 has been completed (paving operations remain).
(Rev.2) Addressed.
9. Show CE draining to sediment trap (or ST device location).
(Rev.2) Addressed.
10. Show low maintenance (not grass) ground cover area(s) for proposed slopes greater than 3:1.
Low maintenance cover is required as a final stabilization measure.
(Rev.2) Not addressed. Show/label areas of constructed slopes that are 3:1 and steeper. I've
identified slope areas steeper than 3:1 with the proposed grading shown on sheets E4 - E14.
(Rev.3) Addressed.
11. Show OP symbol at all ends of pipe outfalls.
(Rev.2) Addressed.
12. Please double check the sheet number references match the right sheet and make corrections.
(Rev.2) Partially addressed. Correct for sheet E5, E12 & E13.
(Rev.3) Partially addressed. Provide match lines, on sheet 12 to sheet 14, and on sheet 14 to
sheet 12.
13. Sheet E4 - Extend OP to an adequate (MS-19)/natural channel (Energy Balance).
(Rev.2) Acknowledged.
14. Sheet E4 - Provide a sediment trap (silt fence inadequate) at low point with diversions going
to it.
(Rev.2) Addressed.
15. Sheet E5 - Show diversion (DD) along LOD perimeter near lots 25 and 26.
(Rev.2) Addressed.
Engineering Review Comments
Page 8 of 11
16. Sheet E7 - Show diversion (DD) along LOD perimeter beside Elmcroft Circle.
(Rev.2) Addressed.
17. Add ST-12 (missing) design to table of detail.
(Rev.2) Addressed.
18. Re -compute earthwork cut/fill volumes shown on sheet E12 to incorporate any changes to
grading (this will be a road plan comment also).
(Rev.2) Addressed.
19. ESC bond required prior to issuing grading permit.
(Rev.2) Acknowledged.
20. (Rev.2) Recommend revising E&SC plan and narrative - Phase 1 sheets should show only
perimeter controls in place (silt fence, diversions, sediment traps, construction entrance,
etc.) and protective controls of existing site features in the disturbance (drainage &
waterways, trees, etc.).
(Rev.3) Acknowledged.
21. (Rev.2) Temporary CE, (Std. & Spec. 3.02) needs to be shown located at the beginning of
the proposed project in order to meet the minimum State requirements. Once the grading
and road surface has been installed, the Owner can work with the E&SC inspector to move
the Temp. CE as needed to protect the pavement as required.
a. Please correct the narrative accordingly (B12/E2).
(Rev.3) Addressed.
22. (Rev.2) Sheet E5 -
a. Make the silt fence continuous (near elev. 690' bottom grade) to provide a more effective
trapping barrier. (Rev.3) Not addressed. It appears that sediment laden runoff will
flow out from ends.
b. SCC-2 outfall velocity of runoff will erode bank unless adequately contained.
(Rev.3) Addressed.
c. Culvert A outlet protection should run parallel with pipe and not askew. Discharge
could potentially blowout and erode protection there. (Rev.3) Acknowledged.
d. Outlet protection (riprap) will need to be extended into adequate receiving channel.
(Rev.3) Acknowledged.
e. Provide stream protection controls for the crossing (ESC). AES 12-15 (Rev.3) Not
addressed. You need to show USC (Std. & Spec. 3.25) for the pipe, and SC (Std. &
Spec. 3.24) for temp. vehicle crossing.
E (Rev.3) Revise Culvert A need to be oriented to the existing stream.
g. (Rev.3) ST-IA: Provide baffles.
It. (Rev.3) Provide inlet protection for pipe, lower right corner of plan sheet.
i. (Rev.3) Provide Construction Staging and Parking Area ESC measures.
23. (Rev.2) Extend channel/outlet protection (Culvert H, Culvert K, SCC-11A, SCC-12, SCC-
24, SCC-20, SCC-13, SCC-18, SCC-19). MS-8 (Rev.3) Acknowledged.
24. (Rev.2) Provide riprap stone sizing is adequate for all proposed channels (Std. and Spec
3.19, Appx 3.19a). (Rev.3) Acknowledged.
25. (Rev.2) Sheet E5/E10 - Move E&SC controls & drainage structures out of stream buffers &
existing steeps slopes that are not part of the road design where possible. 17-603 B/17-405 A.6.
(Rev.3) Not fully addressed. Correct me if Pm wrong but ESC + measures are in place
upstream of Culvert A such that the diversion & trap can be eliminated Temp. diversion (DD)
should be removed from the buffer. ST-2 should be removed.
26. (Rev.2) Provide additional stream protection controls were needed (ESC) & details. MS-12-15
(Rev.3) Not addressed. You need to show USC (Std. & Spec. 3.25) for the pipe, and SC (Std.
& Spec. 3.24) for temp. vehicle crossing.
27. (Rev.2) Sheet 14 - Provide SCC (Std. & Spec. 3.17) and Rip -rap (Std. and Spec 3.19) details.
Engineering Review Comments
Page 9 of 11
Specify filter/lining to be used. (Rev.3) Addressed.
28. (Rev.2) (CW) is not the State symbol for Std. and Spec. 3.09 (Temporary Diversion Dike) as
stated in the Legend and E&SC narrative. Please correct the submittal to reduce potential
confusion between the inspector and owner/contractor. (Rev.3) Not addressed. Fix legend,
Sheet 2 only. Keep the CW label on the plan sheets where previously needed.
29. (Rev.2) Temporary Diversion Dike (Std. and Spec. 3.09) have a maximum allowable drainage
area of 5 acres. Drainage areas of 5 acres or more should have a SCC (Std. & Spec. 3.17).
(Rev.3) Label the CW SCC diversions where used for clarification.
30. (Rev.2) Show OP at ends of the temporary diversions (CW). (Rev.3) Addressed.
31. (Rev.2) OP (Std. and Spec. 3.18) should not be used on slopes steeper than 10%. Riprap
should be used to protect the slope and/or SCC (Std. & Spec. 3.17) designed to an adequate
receiving channel or SWM facility. Follow E&SC, Ch. 5 guidance. (Rev.3) Acknowledged.
32. (Rev.2) Sheets E14/E16 - The drainage area to traps must include all area(s) diverted to it
for volume/sizing purposes. (Rev.3) Acknowledged.
33. (Rev.3) Across all plan sheets:
a. Provide multiple existing contour labels, to aid plan review.
b. Label sediment trap (ST) weir length x width dimensions, in plan views.
c. Ensure all LOD allows practical construction; as expand LOD, where, and as
needed; for example:
i. Sheet 5-6, inadequate access to construct ST-2.
ii. There may be other examples.
iii. Also, revise LOD and revise all information, reports, registration, SWPPP,
design (VaRRM.xis), etc. that may be affected by increase in LOD.
d. Check design against 18-4.3.3; specifically:
i. 18-4.3.3.C.1 requires reverse slope benches.
ii. 18-4.3.3.C.4. Surface water diversions: mentioned elsewhere. The plan
provides a thoughtful elements, including 26 conveyance channels, but
additional surface water diversions may be needed.
e. For all diversions:
i. Label either DD, or CWD.
ii. Report upslope DA, all diversions.
iii. Include DA and diversion type labels for all diversions, all plan sheets
f. Silt fence (SF):
i. Ensure 5-7' offset between SF and base of disturbed slopes; ref. VESCH Std.
and Spec. 3.05, Design Criteria L, p. III-20.
ii. Provide across ESC phase 2 plan sheets, wherever appropriate; for example,
SF is often still required at toe of proposed fill slopes in ESC phase 2.
Compare sheet 4-5 (ESC phase 1) with sheet 13 (ESC phase 2); other
examples exist.
34. (Rev.3) Unless overlooked, construction sequence relative to installation, maintenance, and
removal of ESC measures, is missing. Please provide comprehensive ESC implementation
narrative, with notes.
35. (Rev.3) Provide non -generic topo-specific sediment trap design: tables, profiles, elevations,
calculations, and, especially, existing topography in profile views, for ST 1-13. Limited plan
view data is provided, and no profiles for any ST. Please do not submit generic VESCH
profdes for ST 1-13.
36. (Rev.3) For all sediment traps discharging (via weir) to channel or to undefined (existing
slope) topography or proposed fill slopes greater than 20' vertical interval above base of
slope elevation, calculate Vel.2-yr at weir. For velocity >317ps, provide EC -II or EC-11I from
weir to point downslope where discharge velocity during the 2-yr event is non -erodible.
Albemarle draws on experience at similar high vertical relief development in ensuring
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discharge, whether construction or post -construction phase at Ashcroft, is reasonably non -
erodible. Present discharge velocity as table values, with proposed protection.
37. (Rev.3) Sheet 6 — ST-2: Provide baffles.
38. (Rev.3) Sheet 7 - right panel: delete SWM-1 label.
39. (Rev.3) Include trash rack with anti -vortex device for any VESCH measure requiring riser
standpipe.
40. (Rev.3) Sheet 14 —
a. It is unclear if SWM-1 is to function as a sediment basin: if so, provide complete SB
design for this facility, label it.
b. If not, please remove SWM-1 from ESC plan sheets across the plan set.
41. (Rev.3) Replace SF check dams with stone check dams. Topography does not favor SF
check dams.
42. (Rev.3) Provide profiles for all conveyance channels for entirety of their length where there
are check dams in place; show check dams in profile.
43. (Rev.3) Review remaining traps for need for baffles; wherever baffles are required:
Provide ref. to typ. VESCH baffle detail on plans.
44. (Rev.3) Provide VESCH stone check dam detail.
Additional (Road plan) comments: Note: Comments moved to roadplan review, SUB2018-
20.
A. Sheet E14 — The road plan sheet 19 lists BW (bottom width?) in the remark's column. Are
these all V-ditches now? Update the channel calcs for the road plan (Road plan comment).
B. Endwall required for culverts 48" or wider (VDOT drainage manual, Ch 8).
C. Sheet 20 — (VDOT drainage manual, Ch 8)
a. Culvert H should use the 25-yr design. State the design storm frequencies used?
b. Culvert B — Headwaters < 1.5 x culvert height.
e. Culverts (general), (HW/D) should be at least 1.0 and not exceed 1.5.
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 plan review staff are available from 2-4 PM on Thursdays, should you require a meeting 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
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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 entails 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.albemarle.org/deptforms.asp?department—edengMo
File: WP0201000056 WPO200700053 (amendment) Ashcroft - Phase III - 2-2021 rev[31 docx