HomeMy WebLinkAboutWPO201700075 Review Comments WPO VSMP 2019-09-20COUNTY 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 (Amendment)
Project title:
VSMP Plan Amendment for Crozet Court
Project file number:
WP0201700075 (Amendment 1)
Plan preparer:
Shimp Engineering [ justinAshimp-engineering com ]
Owner or rep.:
Stony Point Design/Build LLC
Chris Henry [ chenry�abstonypointdb.com ]
Plan received date:
15 Mar 2019
(Rev. 1)
12 Aug 2019
Date of comments:
29 Apr 2019
(Rev. 1)
20 Sep 2019
Reviewers:
John Anderson
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 for minor reasons. 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: Submit revised Registration Statement (Sec. 1; Acreage has increased), and revised SWM and
ESC plan sheets (Sec. 4, 5), once ESC /SWM Plan comments addressed. (Rev. 1) Addressed. As ollow-
W: Update on -site field copy of SWPPP (ESC /SWM Plans) as soon as possible. Submit revised 11" x 17"
SWPPP ESC-SWM Plan inserts, once revised /approved (.PDF update is sufficient for Albemarle County
file copy of SWPPP).
B. Pollution Prevention Plan (PPP)
The PPP content requirements can be found in County Code section 17-404.
1. Revise SWPPP Exhibit, as needed (SWPPP, Sec. 6). (Rev. 1) comment persists. Update on -site field
copy of SWPPP /PPP Exhibit as soon as possible.
C. Stormwater Management Plan (SWMP) — Prior comments (addressed, shown in grayscale. Limited ollow-
yp required.
VSMP Regulation 9VAC25-870-108 requires the VSMP authority to approve or disapprove a SWMP. This plan is
disapproved for minor reasons listed, below (See ollow-u ). The stormwater management plan content
requirements can be found in County Code section 17-403.
Sec. 17-208 lists a $200 per plan review fee for Amendment to an approved plan. Amendments typically
entail minor revisions. Not in this case. Limits of disturbance increase; boundary adjustment proposed;
SWM calculation packet is revised; routings have changed; mitigation plan is revised. For these reasons,
please provide revision clouds for any change to plan data, tables, design, notes, labels, etc., revised with
this Amendment application. Without cloud revisions to direct attention to elements proposed to change
with this Amendment, all elements require review. Reviewer commits to provide comments within 20
business days of receipt of revised plans, registration statement, SWM calculation packet (item 6.).
Engineering Review Comments
Page 2 of 4
3. Please submit $200 with each subsequent plan review, including .PDF preview/s.
4. Delete C1 note reading `Crozet Court HOA shall maintain all onsite BMPs,' a note without force apart from
recorded legal instrument. Note re. HOA has no legal effect if shown on VSMP Amendment plan. (Rev. 1)
Withdrawn.
5. 50' distance from stream centerline has meaning, but code does not define the term 50' stream buffer.
Please discontinue use of 50'stream buffer label. 50' distance from stream CL is a label option.
6. SWM Calculation packet:
a. SWM quality calculation includes storm runoff pass -through from a 47.14 Ac. offsite area, and
defines POAI to include this area. Offsite runoff from this 47.14 Ac. watershed is unaffected by
development. This unaffected bypass originates offsite, crosses an off -site parcel without any
apparent proposed development activity —a parcel proposed to add acreage to TMP 56-45 via
separate boundary line adjustment (item b.). (Rev. 1) Partially addressed. Asfollow-up: Offsite
area contributes to POAL Revise plans as discussed 9/20 to show that design of —75 LF channel
(x-section, stone depth /size per VESCH, per Vel.2_y, /HydroCAD) between biofilter A outfall and
end of channel at stream /natural drainage complies with quantity standards at 9VAC25-870-
66.13.1. (channel /manmade SW conveyance) and 9VAC25-870-66.C.1. or C.2 (flood protection).
b. Note 5, Amendment Narrative, Cl, reads: `New parcel 56-42A shall be revised with a BLA. 2.18
Acres from parcel 56-42A shall be added to parcel 56-45. The residue parcel, 56-42A, 1.29 Acres
shall be left undisturbed and is not covered by this VSMPA.' This Note may contain acreage and
tax map parcel mistakes. Please check for accuracy.
c. 56-45A2 acreage that conveys bypass off -site storm runoff proposed to be included with Crozet
Court VSMPA Site Runoff Quantity Totals appears to be outside proposed limits of disturbance
(entirely), includes acreage nearly entirely proposed to be placed in forest /open space easement
(to meet 9VAC25-870-66, in tandem with treating on -site flow via on -site BMPs). Without cloud
revisions, it is difficult to gauge effect of new areas not previously included with approved VSMP.
It appears that off -site pre- /post -developed flow is included with site runoff totals in a manner
more nearly aligned with limits of analysis. (Rev. 1) Addressed. Also, seefollow-up at item 6.a,
above.
d. Please revise cover letter d. 3/15/19 Site Runoff Quantity Totals table to more nearly reflect energy
balance for on -site runoff, treated and bypass, excluding off -site area to POA1 (exclude 2S sub -
catchment, pre-dev/off-site Area to POAl). All six 1- , 10-, 100-yr event POAI values will
change. Most critical are 1-yr values. POAI 1-yr post-dev requires slight revision, to 0.23 cfs.
Please revise cover letter table, Pre-Dev POAI, 1-year, to 0.85 cfs (ref. sub -catchment 1 S). Post-
Dev POAL 1-yr (Link 1L) = 0.23 cfs is well below Max Qaevelopea = 0.46 cfs.
e. The situation differs for POA2. Engineering requests no revision to cover letter table values,
POA2, but review of energy balance for POA2 equation shows Max Qaevelopea 0.22 (0.218) cfs.
Hydrocad Link 3L reports 0.23 cfs. This does not meet SWM quantity requirements at POA2.
(Rev. 1) Note: If include off -site bypass area in POA2, energy balance Eq. indicates compliance.
f. Energy balance is met for POAI (once relocated to biofilter pipe outfall, item i), but not POA2.
g. Energy balance equation (calc packet) shows compliance with 9VAC25-870-66 at POAI, and does
not include Ql-year flow=27.92, but cover letter table values include off -site storm events, which
give misleading impression that this development reduces runoff 99.2% which is not the case.
Although a related approach is required when showing compliance with 9VAC25-870-66.B. L-2.
(Limits of Analysis), design that meets energy balance (9VAC25-870-66.B.3.) need not proceed to
the 1 % watershed point of analysis. The actual point where energy balance is required for biofilter
A occurs at pipe outfall of biofilter A, not beyond this pipe outfall. The same applies for POA2
2
Note 1: With addition of —75' channel (manmade conveyance) below biofilter A outfall, energy
balance is not required at this point but at downslope end, at point riprap channel joins the stream
/natural drainage feature. Note2: POA2 is located at biofilter B outfall, which intersects bypass
flow, so bypass flow should be included in POA2 analysis, and is.
Engineering Review Comments
Page 3 of 4
h. Design presents reasonable limits of disturbance, which coincide with 2.30 Ac. Forest /Open Space
proposed post -developed land cover. Unless misreading calculation packet maps and VaRRM
.xls, Amendment requires a separate Forest /Open Space Easement plat, with Deed of Dedication.
Note: SUB201900061 Crozet Court Final Plat proposes 2.37 Ac. Forest /Open Space Easement.
i. POA1 is located downslope of biofilter A, and should be relocated to pipe outfall of biofilter A.
Note: Plan revision will consider channel /flood protection at biofilter A outfall. Also see item 6.a.
j. Engineering cautions against extending biofilter A discharge pipe (extension not required to meet
any design purpose). Approved discharge location is upslope of C4 line labeled 50' stream buffer.
(Rev. 1) Withdrawn.
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. ESC Plan /Amendment: Engineering will comment once plans are re -submitted with cloud revisions. (Rev.
1) As follow-up: New DD proposed to divert runoff from area of disturbance NW of new DD to ST3 has
two 90-deg bends. At each of these locations, sediment -laden runoff will continue in a straight line. Please
provide trapping measure to redirect runoff, which will not turn otherwise, or provide DDs that alternate
such that straight-line flow is redirected by alternating diversion dikes. Discontinuous dikes (dike -gap -dike)
that shift runoff from north side of upslope DD to south side of next DD may serve to redirect storm runoff.
2. Revised biofilter A is included on C14 with Erosion and Sediment Control Details. Relocate to a SWM
Plan sheet. Provide cloud revisions for plan, profile, and all other biofilter A data revised with this
VSMPA. (Rev. 1) As follow-up: Please label biofilter A and B floor dimensions, sheet C13. Please revise
plans to list biofilter A and biofilter B surface area (ft2) to aid bond estimate, construction, and inspection.
E. Mitigation Plan — Prior review comments addressed /acknowledged. Revised Mitigation Plan is approved.
Ex. Mitigation Plan bond amount lists 574 container -grown seedlings. 645 container -grown seedlings are required
under now -approved rev. Mitigation Plan /WPO Amendment. 10% contingency is sufficient for 71 additional plants.
1. $150 Mitigation plan fee is required as soon as possible. Mitigation plan is revised with this VSMPA. Ref.
17-207 for Mitigation plan review fee requirement.
2. Mitigation Plan, C9, blurs distinction between whips (planted 6' x 6' on center, 1,210 plants /acre) and
container -grown seedling tubes (8' x 8' — 700 /acre). Ref. Table B, p. 102 of Riparian Buffers
Modification and Mitigation Guidance Manual ( link:
https://www.deq.vir i,� nia.gov/portals/O/DEQ/Water/Publications/RiparianBufferManual.pdf ).
3. Revise Buffer Planting Instructions, consistent with Riparian Guidance Manual Table B, below.
4. Delete third statement under Mitigation Option A, which is inaccurate. Amendment must elect whether
plants will be whips, or container -grown seedling tubes for bonding, plan approval, and inspection
purposes.
5. Note: Please also see county email (VSMP plan review) sent 12/10/2018 2:22 PM.
6. Note: Mitigation Planting Purchase schedule appears accurate for 8' x 8' plant spacing; that is: container -
grown seedling tubes.
7. New Note: A 75 LF riprap channel is proposed. This channel is within stream buffer, but all available areas
of unvegetated stream buffer except ACSA easement are proposed to be planted with this Mitigation
Plan, so no additional mitigation requirements apply to this SWM facility channel outfall feature.
Please submit .PDF preview of revisions prior to final print submittal. Once ESC /SWM plan sheets are approved,
submit .PDFs (or two print sets) of revised (ESC /SWM plan) I I" x 17" SWPPP inserts (SWPPP Sec. 4, 5).
Once ESC /SWM plan sheets are approved, please submit four (4) print plans for stamped approval.
Engineering Review Comments
Page 4 of 4
Process
After approval plans may need to be bonded given revised ESC (new sediment trap) and alteration of biofilter A.
The bonding process is begun by submitting a bond estimate request form and fee to the Department of Community
Development (Applicant to examine effect of Amendment on existing WPO bond; discussed 9/20/19 —K. Rucker, J.
Anderson). One of the plan reviewers will prepare estimates and check parcel and easement information based on
the approved plans, if necessary. 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. This paragraph largely assumes current /existing WPO bond
amounts are insufficient (SWM, ESC, Mitigation Plans). Ex. Mitigation Plan bond amount is sufficient.
A recorded Stormwater Management Facilities Maintenance agreement should be unaffected, but if 2.30 Acres (or
any acreage) is proposed to be placed in Forest /Open Space Easement, a separate Easement Application and Deed
of Dedication are required to be submitted, reviewed, approved, and recorded. An Easement Plat would be required.
Note: SLTB201900061, under review, proposes 2.37 Ac. Forest /Open Space Easement; this is sufficient to meet
VaRRM.xls., 2.26 Ac.
After bonding and agreements are complete, and deed 'plat -eeo .aoa, county staff will enter project information in a
DEQ database for state application processing (VAR10M007, Permit Modification). Amendment approval need not
wait for subdivision plat recordation. No lots may be sold until Final Plat is recorded, so Amendment may be
approved.
Reminder: Please note recent DEQ email outreach regarding renewal of active VAR10 permits. It is permittees'
responsibility to follow DEQ guidance. No further reminders will be issued. Application to amend an active
VAR10 does not satisfy responsibility to request renewal of current active VPDES VARI OM007 permit.
DEQ SWCGP database indicates VARIOM007 permit was re -issued 7/15/19.
DEQ will review the application information (VSMP Amendment) based on local VSMP authority approval. At this
time, the DEQ portion of the application fees (if any) will need to be paid directly to the state. For fastest
processing, this is done electronically with the emails provided on the application (Registration Statement). 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, at
inspector's discretion (may not be necessary, given project is under construction). If pre -construction meeting is
warranted, Applicant will need to complete the request for a pre -construction conference form. The form identifies
the contractor and responsible land disturber, and the fee remaining to be paid ($0, if $200 per review Amendment
fees are paid). This will be checked by county staff, and upon approval, a pre -construction conference will be
scheduled with the County inspector. A grading permit has been issued for WP0201700075.
County forms can be found on the county website forms center under engineering;
http : //www. albemarle. ore/dei)tforms. asp? department--cdenz"o
Thank you
J. Anderson 434.296-5832 —x3069
WP0201700075 Crozet Court_042919_VSMP—Amend 092019rev1