HomeMy WebLinkAboutWPO202200017 Review Comments WPO VSMP 2022-05-22�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: 664 West Rio VSMP
Project: WPO2022-00017
Plan prepares Shimp Engineering, 912 E. High St., Charlottesville, VA 22902
Stephanie Paul — steohanie e shimp-en ing eering com
Owner /Applicant: Cameron Property Cville LLC — 6805 Morrison Blvd, Suite 250
Charlotte, NC 28211 [ bwalden(i�madisoncaoarouo.com ]
Plan received date: 11 Apr 2022
Date of comments: 22 May 2022
Reviewer: John Anderson, PE
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.
SWPPP
1. SWPPP /calculation cover pages to reference WPO202200017.
2. Revise WPO plan, SWPPP and calculations as needed to reflect change to initial site plan, since it is our
understanding that the ISP is deferred to revise layout consistent with public street requirements.
3. Sec. 1, Registration Statement:
a. Sec. II.F.: List Albemarle MS4 since project is in Albemarle MS4.
b. Sec. II.G.: Recommend revise project start date since ISP deferred.
c. Sec. III: Identify Vol. /type of export material, approved off -site ESC plan /Grading permit #, and
destination for (off -site) excavated material disposal prior to preconstruction and as pre -condition
of state VAR10 permit issuance. Please indicate off -site estimated area to be disturbed.
4. Sec. 3, Nature of Activity:
a. Lists total area of disturbance 3.13 Ac., while registration statement indicates 3.12 Ac. Please
reconcile.
b. Revise Phase L-4. Sequence, once WPO plan sequence is revised.
5. Sec. 4 /Sec. 5 (ESC/SWM plan sheets): Update once WPO plan is revised.
6. Sec. 6.A, PPP Exhibits: Please relocate sanitary waste (ports John) to avoid area upslope of sediment trap.
7. Sec. 6E: Please list an individual responsible for pollution prevention practices prior to state permit
issuance /prior to preconstruction.
8. Sec. 8: Please list an individual responsible for VESCH compliance inspections prior to state permit
issuance /prior to preconstruction.
B. Pollution Prevention Plan (PPP) —see SWPPP items 6, 7 above
The PPP content requirements can be found in County Code section 17-404.
C. Stormwater Management Plan (SWMP)
Engineering Review Comments
Page 2 of 6
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. C1: Revise Cl to incl. ref. to WPO2022-00017.
2. C3/C3-A
a. Revise New V.W. Private SWM facility esmt labels to read public, rather than private.
b. Provide bumper blocks as safety measure at nine perpendicular parking spaces near boundary with
TM. 45-105. Engineering recommends VDOT GR-2 /guardrail at this location, but bumper blocks
as a minimum measure. See proposed grading at this location, C5-A.
3. C4
a. Relocate proposed UG detention away from parking deck entrance. In the future, should
maintenance repair /replacement require excavation, site parking (for block 1 residents) would be
impossible, design is untenable. A possible alternative location for this portion of the proposed
UG detention system is at the opposite end of the parking deck. Engineering cannot approve
current proposed location at entrance to parking deck. Note: all site parking other than the
proposed 2-level parking deck as well as area beneath existing 30' joint access easement (where it
branches to development property) and access aisle fronting storage facility are proposed to
include underground SWM detention systems. Permeable pavers may provide a design alternative
less intrusive and with a less -total effect, since permeable pavers may be repaired or replaced in
sections that avoid wholesale or deep excavation of entire parking areas or drive aisles.
b. Similarly, future access to proposed UG system at edge of dumpster concrete pad is untenable
since:
i. Block 1 residential units may not be deprived of waste disposal service during any period
of future UG system repair or replacement. No alternative to a continuously -available
solid waste dumpsters serving block 1 apartments is practical, or possible (for example:
curbside receptables or temporarily relocated dumpsters that invites damage to pavement
in areas without concrete pad. Revise to provide continuously -available waste disposal
/dumpster location, or alternatively, show -label a second concrete dumpster pad that may
be striped as available parking until required as a temporary dumpster pad. This second
dumpster pad should be designed to present no conflict with future UG SWM detention
system repair or replacement.
c. Delineate /discriminate via linework and labels:
i. Private drainage easement for SWM conveyance /pipe networks upstream of proposed
SWM facility. On -site SWM facilities are designated public, as stated above.
ii. VAR Width Public SWM facility easement
iii. Public drainage easement for SWM facility outfall/s downstream of any proposed SWM
facility.
d. Revisit proposed SWM-related easements to allow offset to proposed self -storage building footers.
Conflict appears imminent. Engineering judgment advises against easement so close to building
foundation which may prevent future access to proposed UG detention system between storage
units and 2-leval parking.
e. Ensure all VAR Width public SWM facility easement widths are consistent with ACDSM
easement diagram, p. 15:
4. C8
Engineering Review Comments
Page 3 of 6
EASENIEYI WIDTH . DIAMETER . 2'. 2 M-P) .10' Q0' \HN. i
f. Dimension riprap outfall protection at public drainage outfall to existing stream (L xW x D).
g. Revise public drainage outfall to existing stream with MI3 that redirects SWM discharge to be
>90-deg. Relative to existing stream downstream reach. Proposed public drainage outfall directs
system discharge upstream. SWM discharge must align (or be > 90-deg.) with downstream reach
to avoid erosion of existing stream, or proposed outfall protection. Revise proposed acute angle of
intersection to >_ 90-deg. Note: Any revision in range 90-135' relative to downstream reach may
require existing stream far -bank structural armoring to prevent erosion of existing stream bank.
>135-deg, erosion poses less concern.
h. Provide lintel detail for public drainage easement if storm pipe passes beneath retaining wall in
vicinity of dumpsters.
i. Label length of each section of proposed UG detention system.
j. Provide /label CG-6 wherever proposed final grade concentrates surface runoff against curbing,
for example: curb lines above Str. E2A, C4, C5, etc.
k. Provide storm runoff capture /conveyance immediately prior to lower -level parking deck entrance,
else lower deck may receive runoff that poses nuisance, or risk, especially in winter. (See C5-A)
1. Two leader lines appear to point to the same pipe leading to Str. A4 and identify this pipe as 18"
HDPE pipe / 6" HDPE pipe. C8 profile clarifies (2 pipes occupy same vertical space). Please
revise labels to indicate 6" HDPE /PVC is below 18" HDPE. Note: C8 identifies 6" pipe material
is PVC while C4 indicates 6" pipe is HDPE, please clarify 6" pipe material.
in. Provide 84" CMP detention system (System 1) label and 96" CMP detention system (System 2 ,
consistent with C8 system labels /profile captions.
n. Show parking deck (leader line) connection with either system 1 (84" CMP) or system 2 (96"
CMP).
a. Structure A4 detail appears to propose a 0.75" DIA (`0.75" Hole drilled at bottom of cap') low -
flow orifice. This exceeds bounds of acceptable engineering practice for SWM facility design.
2.5"-Y is a reasonable lower limit for low -flow orifice DIA. While 3/d' may satisfy SW water
quantity detention requirements in theory, orifice of this slight dimension may obstruct almost
immediately, even by innocuous items (debris, cloth), no matter frequency of maintenance, or
inspections. Obstruction of/d' orifice short-circuits the entire detention system design, with water
quantity requirement/s then not met. Please revise design, Str. A4, and underground system
components upstream of A4 to provide a more resilient /reliable /practical low -flow orifice DIA.
3/I' DIA low -flow orifice cannot be approved.
Engineering Review Comments
Page 4 of 6
b. Str. D3: comments at item a., above, apply to this structure, as well (0.75" orifice)
c. Show VDOT safety slab (manway pass-thru) in 72" and 60" NM-1, and MH-1 steps in plan view
to ensure no conflict with proposed pipes in/out, at ea. str. (Str. A4/DM).
5. C9
a. Label detention pipe floor slope (0.0%, 0.1%, etc.)
b. Provide contractor note to avoid negative detention slope if proposed detention system pipe slope
=0.0%.
6. C10
a. Provide orifice trash rack details for revised low flow orifice DIA. Detail is for 5" orifice.
7. Revise calculations to accommodate any design change.
8. Revise calc. packet cover to ref. WPO2022-00017.
9. General
a. ZMA201800013 staff report makes reference to lack of commitment to construct block 1 building
on Rio Road, while the WPO plan indicates block 1 building will be constructed. Provide WPO
plan design consistent with block 2, block 1 sequence of development approved with
ZMA201800013. Consistency may require additional design detail, notes, labels, calculations,
etc. should Applicant wish to construct only the storage building in block 2, for a period of years,
or even indefinitely. A WPO plan showing entirety of site developed affects review, approval,
inspections, bond amount, routings, calculations, permit close-out, and bond release. A less than
full build -out (especially indefinitely) could disadvantage Applicant from SWM water quality
/quantity perspective. Engineering recommends WPO plan present alternative that shows partial
build -out; that is: SWM design meeting requirements should only the storage facility be built.
Without alternative block 2/storage-only design, Applicant runs risk that SWM system design may
over -control, or that system components may be located in such manner that prevents adjustment
or may increase system expense beyond that required for block 2-only development. As example:
Proposed Phase 3, 4 sequence of construction, CC 11 requires construction of detention system 1
that serves the block 1 residential structure, and then requires construction of system 2 to serve the
storage facility. A system equivalent to detention system 1 might be sufficient to serve the storage
facility only, if shown as an approvable alternative SWM facility design.
b. SWM facility and public drainage deed of easement is required. This is a separate application, and
review. Easement recordation is required prior to WPO plan approval.
c. A discrete SWM plan is not included in the VSMP /WPO plan, only detention system profiles.
Please provide a SWM plan with the VSMP /WPO plan. Include:
i. General Narrative
ii. Ref. to calculation packet (correlate VSMP /WPO SWM plan with calculations)
iii. Summary of storm water quality /quantity compliance (text /tables /narrative)
iv. Pre- /post development land cover values
v. Site and summary tabs from VaRRM.x1S re -development spreadsheet
vi. Letter of nutrient credit availability if nutrient credit purchase proposed
vii. Pre- /post drainage divides
viii. Ref. to 25% on -site ZMA201800013 SWM control requirement.
Please notify reviewer if this information is presented but overlooked.
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. C11
a. Please revise Sequence of Construction notes to explain how SWM facilities installed prior to site
stabilization are protected, how sediment deposits within UG detention systems will be removed,
and how stream adjacent to site is to be protected from sediment that may bypass SWM facilities
should low -flow orifice/s become blocked, or detention short-circuited.
Engineering Review Comments
Page 5 of 6
b. Revise Sequence to clarify storm conveyance elements between /including Sir. A4 and Aldo not
occur as depicted in Phase 1 of ESC plan.
2. C12
a. Storm conveyance system elements between /including A4 and Al may not be installed at this
early stage of clearing. These are final storm conveyance elements, and proposed phase 1 ESC
plan showing these elements with discharge to an existing stream is nearly certain to invite stream
impact during land disturbance in initial constructive phase. Installation of storm conveyance
system elements is disapproved at this point in ESC /land clearing sequence. Revise ESC plan to
remove these elements.
b. Label ST weir 15' (wide /long?) weir length, or width. Clarify weir dimensions.
c. Show change /modification to existing curb to roll-top along Rio Road West at PCE, such that
curb is mountable to construction vehicles.
d. Revise CE to P(paved)CE.
e. Obtain VDOT land use permit for Rio Road W, prior to working within public RW.
3. C13
a. As permanent storm conveyance /pipe elements downslope of sediment trap may be unavoidable
once block 2 storage facility footers are built, consider /explain how these storm elements and
stream are to be protected during phase when earth is disturbed, and sediment trap sediment -laden
discharge to pipes /stream is possible, or likely.
b. Please revise ESC legend to identify RWD as right-of-way diversion, rather than temporary
diversion dike.
4. C16
a. Include paved construction entrance detail, ACDSM p. 8.
b. Provide Mfr. underground detention system:
i. Installation notes
ii. System details
iii. Maintenance schedule
iv. Periodic inspection checklist
c. Include Construction Record Drawing (As -built for VSMP (.PDF) on plans.
Process:
After approval, plans will have 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 have to be completed by the owner and submitted along with cash,
certificates or sureties for the amounts specified. The agreements will have to be approved and signed by the County
Attorney and County Engineer. This may take 24 weeks to obtain all the correct signatures and forms.
Stormwater Management Facilities Maintenance agreements will also have to be completed and are recorded. The
County's Management Analyst or other staff will prepare the forms and check for ownership and signature
information. The completed forms will have to be submitted along with court recording fees.
This project proposes nutrient credit purchase 0.96 lbs. and requires SWM facility and SWM facility access
easements. This project may also require forest -open space easement (for SWM purposes).
After bonding and agreements are complete, county staff will 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 have 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
Engineering Review Comments
Page 6 of 6
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 must 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 VSW 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 Applications:
httos: //www. albemarle. ore/government/community-develonment/aooly-for/engineering-anol is ations
Thank you.
Please call if any questions — tel. 434.296-5832-x3069, or email 4anderson2(&a1bemarle.org.
WP0202200017 664 W Rio VSMP 052222