HomeMy WebLinkAboutWPO202200029 Review Comments WPO VSMP 2022-08-16�q off nig 401 McIntire Road, North Wing
Charlottesville, VA 22902-4579
County of Albemarle Telephone: 434-296-5832
COMMUNITY DEVELOPMENT DEPARTMENT WWW.ALBEMARLE.ORG
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VSMP Permit Plan Review
Project title: Monticello Contemplative Site — VSMP
Project file number: WPO2022-00029
Plan preparer: Kim Roeser, PE / Timmons Group [ kim.roeser(Ltimmons.com]
608 Preston Ave., Suite 200 / Charlottesville, VA 22903
Owner/Applicant: Thomas Jefferson Memorial Foundation, Attn: CFO Qhallock(a),monticello.org
P.O. Box 316, Charlottesville, VA 22902
Plan received date: 11 Jul 2022
Date of comments: 16 Aug 2022
Reviewer: John Anderson, PE, CFM
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 disapproved for reasons listed below.
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 ESCP, (3) a SWMP, and (4) any TMDL measures necessary.
1. Submit SWPPP: please use county template.
a. Ensure (VAR10) CGP Registration Statement is complete. Include ref. to WPO2022-00029 in
SWPPP title.
b. Ensure SWPPP includes PPP Exhibit /SWPPP, Sec. 6.A. Ensure exhibit shows (initial locations
of):
1. Rain gauge
2. Vehicle wash station
3. Portable sanitary facility, as needed
4. Solid, non -hazardous waste dumpster, as needed
5. Slight depression /catchment for collecting vehicle wash waters, as needed
B. Pollution Prevention Plan (PPP) — See above item l.b.
The PPP content requirements can be found in County Code section 17-404.
C. Stormwater Management Plan (SWMP)
VSMP Regulation 9VAC25-870-108 requires the VSMP authority to approve or disapprove a SWMP. This
plan is disapproved for reasons listed below. The stormwater management plan content requirements can be
found in County Code section 17-403.
1. C0.0: Revise title page of WPO plan /calculation packet to include reference to WP0202200029.
2. C2.0: Provide more specific project location data, where is contemplative site located? Provide Iat.Aong. or
distance (leader line w/ note) to an easily identified landmark at this property.
3. C4.0: Identify variable -width path surface material (path leading to benches).
4. For ELS, overall slope and width requirements downslope of an ELS are specified in Table 2.2, VA DEQ
Stormwater Design Specification No. 2. It does not appear slope below ELS meets design criteria (Max.
slope /Min. width), please revise design /proposed grade, as needed, to qualify for 9VAC25-870-66.D.
Engineering Review Comments
Page 2 of 4
Design is evaluated against this VAC text: "Increased volumes of sheet flow resulting from pervious or
disconnected impervious areas, or from physical spreading of concentrated flow through level spreaders,
must be identified and evaluated for potential impacts on down -gradient properties or resources. Increased
volumes of sheet flow that will cause or contribute to erosion, sedimentation, or flooding of down gradient
properties or resources shall be diverted to a stormwater management facility, or a storrnwater conveyance
system that conveys the runoff without causing downgradient erosion, sedimentation, of flooding."
Table 2.2. Fitter Ship Design Criteria
Design Issue
Conserved Open Space
Vegetated Filter Strip
Soil and Vegetative
Amended soils and dense turf
Cover
Undisturbed soils and native
cover or landscaped with
(Sections 6.1 and
vegetation
herbaceous cover, shrubs, and
6.2)
trees
1% to4%Slope -Minimum 35
0.5%to 3%Slope -Minimum 35ft
ft. width
Overall Slope and
width
4% to 6% Slope - Minimum 50 ft.
Width (perpendicular
3% to 6% Slope - Minimum 50 ft
width
to the flow)
width
6% to 8% Slope - Minimum 65 ft.
(Section 5)
The first 10 ft. of filter must be 2% or
width
less in all cases 2
The first 10 ft. of filter must be 2%
or less in all cases
Also, DD. 13-14, VA DEQ Spec. No. 2
Engineered Level Spreaders. The design of engineered level spreaders should conform to the
following design criteria based on recommendations of Hathaway and Hunt (2006), or a locally
approved standard that meets the intent of these criteria, in order to ensure non -erosive sheet
flow into the vegetated buffer area. Figure 2.3 above represents a configuration that includes a
bypass structure that diverts the design storm to the level spreader, and bypasses the larger storm
events around the Conserved Open Space or Vegetated Filter Strip through an improved channel.
Version 1.9, March 1, 2011
Page 13 of 20
VA DIED STORMWATER DESIGN SPECIFICATION NO.2 SHEET FLOW TO FILTER OR OPEN SPACE
An alternative approach is that utilized by Henrico County, where pipe or channels discharge at
the landward edge of a floodplain or stream (Resource Protection Area or RPA) buffer. The
entire flow is directed through a stilling basin energy dissipater and then a level spreader such
that the entire design storm for the conveyance system (typically a 10-year frequency storm) is
discharged as sheet flow through the buffer. (Refer to Henrico County's Environmental Program
Manual: Chapter 9, Minimum Design Standard 9.01 "Energy Dissipator":
htti)://www.co.henrico.va.us/works/eesd/.)
5. Notes:
a. If downslope Max. slope /Min. width for ELS cannot attain Table 2.2 values, an underground
detention pipe shown to meet energy balance at point of release may be an option. Pipes 107, 105,
or 103 may be revised (flatter slope /weir plates) to detain runoff (and meet energy balance).
b. Other possible options:
i. Crown path to direct sheet runoff from portions of path to graded slopes SW of path
(recommend gravel diaphragm at edge of path).
Engineering Review Comments
Page 3 of 4
ii. Use pervious material for path surface to lessen quantity /quality requirements, may
lower nutrient purchase requirements or reduce or eliminate need for ELS if path
constructed of pervious material.
iii. Gravel diaphragm along NW edge of path to intercept pre -development volume of sheet
flow from areas upslope of path (use 10-yr event).
iv. The only increase in sheet flow with project is due to a path that varies in width, 8.5' to
approx. 27'. If design provides storage for pre -developed overland sheet flow (Qio-n), or
fraction of it, then a portion of upslope DA may be eliminated in post -developed
diagrams /calculations. Several constraints pose challenge: pre -development sheet flow
is not increased yet is blocked by path, limited impervious area of path serving benches.
If path itself is designed to sheet flow (or portion of it) rather than concentrate runoff, it
may ease energy balance requirements, or qualify as compliant under 9VAC25-870-66.D.
c. Any on -site SWM practice (quantity or quality) requires platted SWM facility easement, an ELS
or detention pipe, for example. Gravel diaphragm alone would not, in this instance, but an ELS or
detention pipe would require SWM facility easement.
6. If grade is revised to meet Min. width /Max. slope, then please also revise ELS length to correspond with
LD-229 pipe 101 Qio-y, vmk flo.V =2.89 cfs ( 13 if /cfs). Ref. VA DEQ Spec. No. 2 text at p. 13, image, above.
In this instance, ELS is a quantity not quality measure, so Q10-y, is the relevant design parameter, rather than
1" runoff used in quality treatment design (i.e.: no bypass of ELS during 10-yr event, to qualify for
9VAC25-870-66.D.).
7. C6.1
a. Level spreader detail pop-up emitter design is unclear, provide additional information to clarify
how runoff entering stone section behind ELS discharges through stone bed and/or vertically
through pop-up emitter. Reviewer is unfamiliar with this design.
b. Post -developed condition appears to exclude a portion of up -slope runoff reaching ditch A, revise
to show all runoff perpendicular to and upslope of ditch A as reaching ditch A.
D. Erosion and Sediment Control Plan (ESCP)
Virginia Code §62.1-44.15:55 requires the VESCP authority to approve or disapprove an ESCP. This plan
is disapproved for reasons listed, below. The erosion control plan content requirements can be found in
County Code section 17-402.
1. Provide sediment traps to collect /disperse (via stone weir) CWD runoff at ends of CWDs, otherwise,
CWD will release concentrated runoff to perpendicular slopes where erosion is nearly certain to occur.
2. Revise LOD to show /label construction access. How will equipment (even small grading equipment)
access contemplative site? If via existing path, equipment is likely to disturb underlying soil unless
design stipulates path is to be top -dressed with stone sufficient to protect underlying soil from
frequency /types of equipment that will use the path to access the bench site. Engineering recommends
top -dress to exclude existing gravel path from LOD. In other words, design needs to revise LOD, or
ensure no land disturbance occurs along site access.
`Next Steps' after WPO Plan approval
1. Purchase Nutrient Credits (if required)
a. Please coordinate with the County reviewer before working with a nutrient bank. The reviewer
must confirm if your project must follow the DEQ hierarchy requirements.
b. Letter of availability must be provided on the WPO approved plans.
c. Applicant must contact/coordinate nutrient purchase with Ana Kilmer, akilmer e albemarle.org.
d. Affidavit of Purchase must be provided to Ana Kilmer before a grading permit can be issued.
2. Post WPO Bond
a. Applicant must submit a `Request to Establish a Bond' form and fee to CDD.
Engineering Review Comments
Page 4 of 4
i. Complete the form and email it to akilmer"bemarle.org, along with proof of payment
(see below).
b. Payment can be made either online or with a check.
i. If paying online:
1. Go to the online payment portal.
a. Select WPONSMP as the application `type.'
b. Type in the WPO number and project name in the Notes/Details section of the
form.
C. Type in the `payment amount' as $294.34.
d. Click "Proceed to Secure Checkout" link to make payment.
2. You will receive a receipt in an email.
ii. Email a copy of the receipt to akilmer"bemarle.org.
c. Once the bond request and payment are received, the applicant can provide the bond estimate
(completed on the County worksheet), or Engineering staff will complete the estimate. Once the
estimate is approved, Ana Kilmer will contact and work with the applicant to post the bond.
Obtain DEQ Permit (ifLOD > 1 Ac.)
After nutrient credits have been purchased and the bond has been posted:
a. County staff will register the project with DEQ.
b. Applicantloperator listed on the Registration Statement will receive an email with instructions on
how to pay the DEQ permit fee.
c. Applicant must email a copy of the DEQ receipt of payment to charris@albemarle.org.
albemarle.org,
d. DEQ typically will issue a permit within 2 weeks of receiving payment.
4. Request pre -construction meeting:
a. Complete and email the Request for a Preconstruction Meeting and Grading Permit
to charris(2,,albemarle.org.
b. Pay the fee via the online payment Portal or a check at the pre -construction meeting. If paid
online, email a copy of the receipt to charris(a),albemarle.org.
All steps must be completed before the grading permit can be issued.
County forms can be found on the county website forms center under Engineering Applications:
httos: //www. albemarle. org/govemment/community-develol)ment/al)ply-for/engineering-auvl ications
Thank you.
Please call if any questions - tel. 434.296-5832-x3069, or email 4anderson2(a)albemarle.org.
WP0202200029-Monticello Contemplative Site-VSMP-081622