HomeMy WebLinkAboutWPO202200028 Review Comments WPO VSMP 2022-08-17County of Albemarle
COMMUNITY DEVELOPMENT DEPARTMENT
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VSMP Permit Plan Review
Project title: VSMP Plan for Rivers Edge
Project file number: WPO2022-00028
Plan prepares
Shimp Engineering, 912 E. High St., Charlottesville, VA 22902
Justin Shimp, PE,Iustin(a),,shimu-engineering.com
Owner or rep.:
Rivers Edge Holdings LLC
P.O. Box 6458, Charlottesville, VA 22906
Applicant:
Tom Weeks — eeks e rocketmail.com
P. O. Box 1033, Troy, VA 22974
Plan received date:
8 Jul 2022
Date of comments:
17 Aug 2022
Reviewer:
John Anderson, PE, CFM
401 McIntire Road, North Wing
Charlottesville, VA 22902-4579
Telephone: 434-296-5832
WWW.ALBEMARLE.ORG
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 ESOP, (3) a SWAP, and (4) any TMDL measures necessary.
SWPPP
1. Please ensure SWPPP cover includes reference to WPO2021-00069.
2. Submit SWPPP using county template located at:
httos: //www.albemarle. ore/home/showoublisheddocument/ 166/637202310327530000
a. Sec. 1: Registration Statement, please complete. Feel free to call if any questions.
b. Sec. 6.A.: PPP Exhibit: Please show initial location of.
i. Rain gauge.
ii. Portable sanitary facilities (ports John), as required.
iii. Covered non -hazardous waste dumpster, if required.
iv. Vehicle wash waters, draining to trapping measure (Not a sediment trap design, per se,
but shallow depression — 1-2 backhoe buckets. Avoid direct drainage to Ex. storm
system, or pond/s.)
v. Concrete wash -out.
vi. On -site fuel, if required.
vii. Paint, stucco, chemical storage, if required.
c. Sec. 6E: List named individual responsible for PPP measures.
d. Sec. 8: List named individual responsible for ESC inspections, qualified to evaluate compliance
relative to VESCH, Yd Edition, 1992.
e. Sec. 9: Ensure Signed Certification is signed and dated.
B. Pollution Prevention Plan (PPP) — See above item 2.b.
The PPP content requirements can be found in County Code section 17-404.
C. Stormwater Management Plan (SWAP)
Engineering Review Comments
Page 2 of 5
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. Provide SWM desim
a. Initial submittal does not include specific SWM plan or design information either for underground
detention, or dry pond 1.
b. Include:
i. SWM design details, plan /profile, for underground detention system and dry pond.
Partial profile of UG detention is insufficient for review, construction, bonding, or
inspection purposes.
ii. Ensure SWM facility profiles are specific to site, show existing and proposed grade.
iii. Include SWM facility access to dry pond (10' width, max. slope 20%).
iv. Label all pipe riprap outlet protection dimensions (L x W x D) incl. dry pond inlet pipe/s.
v. Note: Platted SWM facility and public drainage easements (each on -site SWM facility)
must be recorded prior to WPO plan approval. Please submit SWM /public drainage
easement plat at earliest convenience.
vi. Include SWM facility (typical) construction, maintenance, and inspection information for
dry pond and underground (Mfr.) detention systems.
vii. Include Construction Record Drawings (As -built for VSMP policy on the plan.
2. ZNIA201800018 Application Plan, 14 Apr 2020, shows normal crown site access with storm inlets and pipe
conveyance, not 4' ditch section (C9). Revise and provide DI -pipe conveyance per approved ZMA
Application plan. Design must minimize potential impacts to preserved steep slopes, and pipe conveyance
is less likely to present future EP or roadside erosion than grass -lined ditches. Ref. approved ZMA
Application plan, pp 20-22, as well as 1-Apr 2022 initial site plan Engineering review comments, item 61..
Also, 14-410.G./18-32.7.2.2.a Pipe /DIs are deemed necessary to limit erosion of (site access) pavement,
and to minimize impacts to preserved steep slopes situated below site access that is more likely to occur
with grass -lined SCC. Note: Critical safety issue: at different points both sides of site access falls away to
steep, unrecoverable slopes. CG-6 with minimal flat area beyond curb provides wheel -strike barrier to off -
road incident, whereas ditch section without shoulder does not. Proposed site access provides SCC nearly
immediately adjacent to paved surface (SCC itself a hazard) without shoulder with intermittent drops to
steep unrecoverable slopes. Site access design is problematic from safety, drainage, and prior -approval
standpoints. Substantial additional guardrail is requisite with current design (no curb), with placement of
SCC checked against guardrail and space constraints, but this point is likely irrelevant as WPO plan must
conform with ZMA Application plan and ordinance requirements for adequate drainage and ordinance
mandate to minimize potential impact to preserved steep slopes.
3. C9 (Also related to ISP): Locate 3" FM outside edge of (site access) pavement, consistent with approved
ZMA Application Plan sheet 12. FM located within /beneath pavement limits access to utility and access
to residences for Rivers Edge residents in event of FM break, repair, or replacement. If site access storm
design is revised to provide DI/pipe conveyance, it should be possible to locate FM opposite pipe (other
side of travelway), or possibly in same utility trench as storm pipe, with offset, as needed. SP201800023
includes Preliminary Central Sewage System Plan for River's Edge. This plan shows 3" FM outside paved
surface of site access. Revise plan per approved ZMA Application Plan and SP201800023 Preliminary
Central Sewage System Plan for River's Edge.
4. C10
a. Ref. ISP Engineering review comment (4/l/22), item 6.e., and revise CIO 340 LF UG detention
system, per ISP comment. See ISP comment for rationale. Design shows no change to proposed
UG detention system in response to April 2022 ISP review comment, which may cause delay. As
noted in ISP review item 6.e., proposed 340 LF UG detention is inconsistent with approved ZMA
Application plan, and will not be approved. Additional comments possible with revised design.
b. Engineered Level Spreader (ELS) downslope of 340 LF UG does not meet VA DEQ Storrrrwater
Design Specification No. 2 Table 2.2 Min. width /Max. slope requirements, or Max. L if designed
Engineering Review Comments
Page 3 of 5
to transition 10-yr concentrated post-dev UG detention discharge to sheet flow (Also, item 4.e.i.
below). An ELS in this location appears incapable of meeting ELS design criteria. Please see
Engineering ISP review item 2.c. and revise design. Proposed 5' trail near the river (downslope
of proposed ELS) will likely experience erosion with proposed design since discharge from ELS
to slopes is anticipated to cut /create new drainage patterns as it traverses slope and reaches
/transits proposed trail. Please provide storm pipe across preserved slopes to edge of N. Fork
Rivanna River (storm pipe across preserved steep slopes is permissible provided no other
alternative exists, none appears to), storm discharge at this location should be evaluated to ensure
it meets energy balance requirements with outfall protection designed per VESCH Std. & Spec.
3.18. 59-p. Calculation packet, p. 1, indicates discharge from the new UG detention system
`releases the 1-yr storm at rates complaint with the Energy Balance Equation,' in which case, it is
simply a matter of conveying detention system discharge via pipe across slopes, beneath trail to
the river. See design for dry pond outfall pipe which extends to edge of N. Fork Rivanna River.
Additional comments possible with revised design.
c. C 14: Provide profile for ELS to correspond with Calc. packet, p. 1 statement: `This runoff will be
released to a Level Spreader which will convert the concentrated flow to sheet flow across a
1.77% slope for 112-ft before reaching the river banks.'
d. Provide SWM narrative and design conveyance for site discharge across 5' trail. Please note calc.
packet pg.1 peak discharge POA 1 table value, 56.52cfs. Design cannot predict with reliable
assurance that 56.52 cfs during the 10-yr event will sheet flow across the 5' trail without
significant erosive effect. As mentioned elsewhere, sheet flow on even moderate slopes tends to
reconcentrate and establish drainage patterns that would likely subject the 5' trail to persistent or
intractable erosion or maintenance issues. Design should route site discharge beneath trail to river
edge. Ref. ZMA Application, sheet 23, which shows discharge at N. Fork Rivanna River edge.
Eliminating an ELS at this location also eliminates issues that typically attend ELS construction
/maintenance. Any measurable departure from 0.0% grade for an ELS typically causes an ELS to
discharge not as sheet flow, but at the low point along an ELS, as concentrated flow.
e. Calculation packet
i. Flood protection, POA 1: Clarify how post-dev 10-yr release rate (56.52 cfs) meets
9VAC25-870-66.C. requirements. Also, ELS design problematic if post-dev 10-yr peak
flow =56.52 cfs. (ELS design criteria [VA DEQ Spec. No. 2, Table 2.2] requires 131f
ELS /cfs, with 130' Max. ELS Length). Note: POA 1 poste-dev 10-yr discharge is higher
than pre-dev POA 1 pre-dev discharge, but POA 1 may still comply with 9VAC25-870-
66.C.2. via conveyance design that confines the post -development peak flow rate from
the 10-year 24-hour storm event within the stormwater conveyance system.
ii. Additional comments possible since Engineering anticipates site access drainage design
and SWM UG detention design to change.
iii. Graphic, p. 4 and 17, Calc. packet, POA 1 does not align with plan UG detention point of
discharge (C12 C13), revise Calc. packet graphics to accurately depict post-dev UG
detention point of discharge. Revise calc. tables, as needed.
iv. Pg.24:
1. Increase pipe diameter or slope, F2 to Fl since 10-yr peak flow (32.51cfs) is
98.8% of pipe capacity. For less frequent events, there is no relief if pipe
capacity is exceeded, drive aisle to lower lot will experience excess runoff
/flooding.
2. Recommend:
a. Increase pipe diameter or slope, 172C to 17213. (18" HDPE pipe, 0.90%
slope is at 98.4% capacity for 10-yr event)
b. Increase pipe diameter or slope, F2B to 172A. (same, 98.4% capacity)
5. C 11: Ensure SCC inlet to dry pond 1 has riprap outfall protection to protect dry pond 1 floor (similar to
outlet protection shown at pipe inlet to dry pond 1).
6. C 13: Provide storm conveyance (ditch to DI-7) behind CG-6 west of site access (travel way, = contour
446'). Design spills runoff over curb onto pavement. Eliminate overland runoff to paved surface.
Engineering Review Comments
Page 4 of 5
Engineering also recommends nominal width for pedestrians who may be forced by circumstance to walk
along site access. Note: Although existing driveway is converted to a pedestrian path, this path will likely
transit unlit remote forest. Any number of residents may wish to avoid remote path at night /in darkness, in
which case, residents forced to walk the distance, Rt. 29 to their home may welcome a flat area more easily
accessible and highly visible adjacent to River's Edge primary site access.
7. Show steep slopes on Site, Utility, and Grading Plan sheets, similar to floodplain and stream buffer limits,
which are shown, since design and impacts cannot be evaluated unless steep slopes are delineated (shown
/labeled).
8. C 14: Wherever vertical difference between DW in and INV out exceeds 4', please provide label on storm
sit. profile for %:" steel plate in MH floor, str. F2 and F4, for example. [VDOT Drainage Manual, p. 9-37,
9.4.8.7, Maximum Grades]
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. C19-C21
a. Show and label steep slopes.
b. Provide plan notes requiring contractor to:
i. Delineate /flag limits of preserved steep slopes which intersect LOD.
ii. Flag approved plan limits of disturbance within preserved slopes, the point beyond
which disturbance or impact to steep slopes may not occur.
iii. Replace /maintain steep slopes delineation flagging for duration of project.
2. C19
a. Show /label paved construction entrance at Rt. 29.
i. Revise PCE at Rt. 29 to show paved construction entrance beginning at edge of
shoulder, not edge of Rt. 29 thru travel lane.
b. Label ST 1 floor dimensions (L x W). Also, sheet C22.
3. C21
a. Label ST 3, 4 floor dimensions (L x W). Also, sheet C24
4. C22
a. Show Aabel outfall riprap dimensions (15" HDPE, L x W) at N. Fork Rivanna River.
b. Provide adequate temporary ESC measures for storm pipe corridor to river (incl. VESCH
abbreviations for measures).
5. C26
a. Revise sediment trap design table, ST 4, to provide wet -dry storage volume for 1.83 Ac.
(Phase 1) DA.
b. Recommend provide 2 separate ST design tables, for ESC phase 1 and 2, since drainage areas
contributing runoff to sediment traps vary considerably, phase 1 to phase 2. Ensure STs are
sized appropriately, whether in phase 1 or 2.
6. Label ST floor dimensions on plan sheets, L x W (phase 1, phase 2).
`Next Steps' after WPO plan approval
1. Purchase Nutrient Credits (6.17lb. nutrient credit purchase 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"bemarle.ora.
d. Affidavit of Purchase must be provided to Ana Kilmer before a grading permit can be issued.
Engineering Review Comments
Page 5 of 5
2. Post WPO Bond
a. Applicant must submit a `Request to Establish a Bond'form and fee to CDD.
i. Complete the form and email it to akilmergalbemarle.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 a 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(a,)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 charrisAalbemarle.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:
https: //www.albemarle. org/govemment/communiiy-development/apDIV-for/engineering-applications
Thank you.
Please call if any questions — tel. 434.296-5832-x3069, or email ianderson2&a1bemarle.org.
WP0202200028_Rivers Edge-VSMP_081722