HomeMy WebLinkAboutWPO201500025 Review Comments WPO VSMP 2015-08-13Engineering Review Comments
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COUNTY OF ALBEMARLE
Department of Community Development
401 McIntire Road, Room 227
Charlottesville, Virginia 22902 -4596
Phone (434) 296 -5832 Fax (434) 972 -4126
Project title:
Project file number:
Plan preparer:
Owner or rep.:
Plan received date:
(Rev. 1)
Date of comments:
(Rev. 1)
Reviewers:
(Rev. 1)
VSMP Permit plan review
CMA Properties
WP0201500025
Collins Engineering
CMA PROPERTIES INC
20 April 2015
7 Jul 2015
4 Jun 2015
13 Aug 2015
Max Greene, Michelle Roberge
John Anderson
[email]
[pborches@,cmacars. com]
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 SWAP, and (4) any TMDL measures necessary.
Comments reference digital SWPPP updated 7/2/2015. Recommend do not re- submit SWPPP until ESC /SWM plan
comments addressed. SWPPP contains reduced -size ESC and SWM plans.
Clarify the approved permit from DEQ. A permit is granted for an approved VSMP
plan. Is this an amendment to an approved plan. (Rev. 1) Addressed. 7 -Jul Applicant
response: "The Area of Disturbance Exhibit within the updated SWPPP report shows
the limits of disturbance covered under the approved permit from DEQ for the CMA
Properties." Confirmed 12- Aug/image:
Name
Cl Colonial Auto Center
Address Line 1
100 Myers Dr and 689 Greenfield Ln
city
Charlottesville
Latitude (e.g. 37.1234)
38.0868
Project Info
status
Private
Nature of Construction Activity
Commercial- Car Dealership
Est. Project Start Date (MMfDDfYYYY)
0210312014
Est. Project End Date (MMfDD1YYYY)
06!28!2019
Est. Area to be Disturbed (Acres) (e.g. 1.23)
9.00
State
VIRGINIA
Address Line 2
No Data
zip
22901
Longitude (e.g. - 78.1234)
- 78.4751
a1S4 Operator
No Data
Total Area of Development (Acres) (e.g. 1.23)
14.37
Part of a common plan?
No
Engineering Review Comments
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New
2. SWPPP p.10, Note 9 & sheet 5 — Replace CE reference to Phase II with phrase Future
Development.
Pollution Prevention Plan (PPP)
The PPP content requirements can be found in County Code section 17 -404.
1) The PPP should be labeled Pollution Prevention Plan and not just another copy of the E &S
plan. Include an 11 "x 17" Pollution Prevention Plan map showing concrete washout, porta-
johns, fueling stations, and trash containers. This will be marked up by the
contractor as construction of site progresses.
As follow -up:
1. Sec. 6.E. — Please identify person responsible for pollution prevention practices.
[VAR10 Part II.A.4.d.]
2. Sec. 6, SWPPP Exhibit, Pollution Prevention Plan — please provide concrete wash -out.
B. VSMP: SWPPP: Stormwater Management Plan (WPO201500025)
VSMP Regulation 9VAC25- 870 -108 requires the VSMP authority to approve or disapprove a SWMP. This plan is
disapproved for reasons provided in comments below. The stormwater management plan content requirements can be
found in County Code section 17 -403
1. Clarify the SWM note on title sheet. It does not match proposed BMP. (Rev. 1) Addressed.
2. It appears the bioretention will be built to be fully operational for phase 1. When phase II is
proposed, the sediment basin 1 will no longer be available. What erosion control measure will be
used then? (Rev. 1) Withdrawn. 7 -Jul Applicant response: "Separate erosion and sediment
control measures can be installed, and reviewed by the County for approval, at the time of Phase
II's development."
3. On sheet 6, the drainage area A is noted as 3.27 acres. State the project site acreage on the
predevelopment inset (5.2 acres ?). It's confusing to label the predeveloped site 3.27 acres. This
project site area 5.2 acres can be used for the predevelopment acreage on the VRRM. Note the
existing parking lot needs a 20% phosphorous load improvement from the pre developed
phosphorous load. (Rev. 1) Withdrawn. 7 -Jul Applicant response: ' — revised plans now show a
subarea `A' watershed of 3.41 acres and the water quality and detention calculations have been
updated accordingly. ... the site's overall water quality compliance for the `total disturbed
acreage' of 4.71 acres is met through subarea A's treatment of 3.41 acres, and these two values are
correctly shown..."
4. On sheet 6, remove the combined phase I & II information. Only show phase 1. It is important to
note that you are showing more than 12" of ponding for Phase II, which needs to be addressed.
This is where more runoff reduction or detention on site is needed like we discussed during the
ZMA. (Rev. 1) Addressed. Design limits bioretention basin max. ponded depth to 12" —sheet 7.
5. On sheet 6, what is the minimum treatment volume referring to? Verify how that was calculated.
(Rev. 1) Addressed. Design relies upon VaRRM .xls Tv / VA DEQ Stormwater Design
Specification No. 9.
6. Clarify treatment volume shown on phase 1 and phase I & II (37,686 cf). The TvBMP is the
treatment volume based on the contributing drainage area to the BMP, TvDA, plus any remaining
runoff volume discharged from upstream BMPs in the treatment train. The treatment volume
includes the volume in the surface ponding, filter media, and 12" gravel. Note this may change
Engineering Review Comments
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with maximum 12" ponding. (Rev. 1) Addressed. As follow -up, relating to bioretention basin
design:
1) Filter Cell, Detention Cell, and Detention + Filter Cell tables are somewhat confusing.
Incremental increases in filter cell Vol. (Elev. 490' -491' for example) appear based on total
Vol., rather than media 25% porosity. Detention + Filter values are not sums of the other two
tables. Confirm values, and assist reviewer. A tel. call may be best.
2) Sheet 7: plan view — please show underdrains to scale, schematically (10' OC), and extend to
edge of basin.
3) Sheet 7: plan/profile — delete phrase `or to daylight into the detention cell' since elevations
don't work. In addition, if underdrains daylight, they may be obstructed by debris, animal
activity, etc, esp. given detained water elevations. If underdrains fail, the basin may fail.
4) PVC cleanout detail — please revise to show Elev. 6 -9" above mulch layer. During ponding
events, caps may be `lost' beneath mulch (personal /contractor experience).
5) Profile /riser note — specify depth of burial of 24" thick concrete foundation.
6) Profile —label basin floor elevation, similar to Glenmore K2C.
7) Bioretention basin landscaping schedule — please list/estimate QTY for: wool grass, Chinese
juniper, switchgrass to aid bond estimates /construction inspection.
8) Plan view —label floor dimensions of forebay, bioretention cell, and detention cell.
Use the 1.10 acres for pre - developed impervious area from the approved ZMA. (Rev. 1)
Addressed.
S. Use .19 acres for open space ( bioretention) in drainage area A. The terraced wall/benching should
not be included. (Rev. 1) Addressed.
9. Provide some sheets in VRRM that are legible. (Rev. 1) Addressed.
10. The riser structure is incorrectly labeled as 15 ". Change to 24 ". (Rev. 1) Addressed.
11. Where is the planting schedule? Show plan view for bioretention plants. Plants selection for 12"
ponding should be looked into. (Rev. 1) Addressed.
12. Show 12" gravel under underdrain. Show in profile on sheet 7. (Rev. 1) Addressed.
13. Clarify the areas that would need 1:1 side slopes for filter media rather than placing a note. (Rev.
1) Addressed.
14. Is there a defined channel for emergency spillway? (Rev. 1) Partially addressed. As follow -up,
acquire temporary construction easement from downslope property owner. Requirements for off -
site easements have acquired priority urgency. Approval requires easement since the 25' wide
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Engineering Review Comments
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emergency spillway cannot be built without an off -site temporary construction easement (TMP
#45- 101B). We accept 7 -Jul response that emergency spillway activates only in a 100 -yr event.
15. On sheet 7, show landscaping buffer as note calls out one. (Rev. 1) Addressed.
16. Verify where the forebay gabion design is from. (Rev. 1) Addressed.
17. Provide the outlet protection design. (Rev. 1) Addressed. As follow-up: Extend riprap to stream.
Appreciate note stating contractor shall not disturb existing wetlands /streams. Revise note (sheets
4, 7) to reference placement to stream. Site visit shows current length of riprap outfall protection
coincident with 110'± of stream (photo, 5/6/14).
04 0F4
18. There is a proposed easement beyond outlet protection. Provide. (Rev. 1) Addressed.
19. Remove the "level 2 minimum 36" note from bioretention detail. (Rev. 1) Addressed.
20. Show geotextile fabric around in basin. See standard. (Rev. 1) Addressed.
New —
21. Provide additional existing contour labels, sheet 7, Level II bioretention basin detail.
Engineering Review Comments
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22. Ref. ACDSM, 6.A.3.b; fig., p. -15. Note: At mid -point of 276 LF detention cell outfall, trench
depth is 11.3' ±. Depth/trench width suggest it will not be possible to preserve the entire 10' X
113' strip labeled to remain undisturbed with phase 1 and to be surrounded with tree protection —
an observation.
23. Recommend MH be placed near midpoint of 276 LF outfall, to provide access for maintenance.
24. Provide yard inlet to capture (turf) runoff in areas west of uncurbed parking aisle to prevent runoff
passing over retaining wall without routing to SWM bioretention forebay; capture is critical —
Also, see ESC comment, La.ii., below.
25. Provide CG -6 in uncurbed areas of paved parking aisle as barrier to silt -laden runoff, as barrier to
prevent deterioration of pavement or turf or impact to facility forebay, or storm inlet. This is a
requirement (18- 4.12.15(g)).
C. VSMP: SWPPP: Erosion Control Plan (WPO201500025)
Virginia Code §62.1- 44.15:55 requires the VESCP authority to approve or disapprove an ESCP. This plan is disapproved
for reasons provided in comments below. The erosion control plan content requirements can be found in County Code
section 17 -402.
1. Basin
a. Phase 1,
i. Basin does not appear to capture the existing swale in the rear of the site. Please add a
diversion or extend the basin over the swale. The 400 feet of drainage swale exceeds
the protective ability of the proposed silt fence that T -bones the Swale. (Rev. 1)
Addressed.
ii. Basin does not appear to capture the existing swale in the front of the site. The front of the
site has a smaller swale ( @200 feet long) with a diversion that bucks grade into the basin.
Please extend the basin to capture this swale, or a better design for the diversion that does
not appear to force stormwater uphill into basin. (Rev. 1) Partially addressed. As ollow-
yp and critical if runoff intended to be captured/routed to bio- retention (or SB 1) is to reach
either: provide permanent swale /ditch and ESC diversion west of existing area to remain
undisturbed within subarea `A' (sheets 4, 5, 6). Sheet 6 (inset) lacks contours to ensure
runoff west of this area will reach the new inlet (corner of paved area). Runoff must reach
this inlet to enter basin forebay. ESC -SWM designs must provide well- defined contours
between this inlet/SB 1 and Berkmar, with contours (or diversion) extending parallel with
Berkmar 150' to the north. Revise inset, subarea A, sheet 6 /SWM; sheets 4 and 5/ESC.
b. Phase 2,
i. Diversion is needed in back of site to help direct stormwater flows into basin after
pipe is installed. Please show the grading for the diversion. (See Std. & Spec. 3.12, design
criteria, page 111 -66) (Rev. 1) Addressed.
ii. Front swale will need to be shown graded into the proposed contours due to proximity to
property line. Temporary grading easement may be required from adjacent property
owner in order to actually construct slope and diversion in location as shown. (See Std.
& Spec. 3.12, design criteria, page 111 -66) (Rev. 1) Not addressed. Repeat request to
carefully examine need for temporary grading easement from adjacent property owner.
In places, proposed grades are within 5' of PL. Also, SWMP, item #14, above.
Emergency spillway,
i. 60' spillway length seems excessive, contractor will have a difficult time
constructing a spillway that equally distributes basin overflow across what is
basically a 60' level spreader. (Rev. 1) Addressed.
ii. Please show armoring of the spillway and state on the plans that the emergency spillway
must be constructed in a manner that allows the basin overflow to equally utilize the
Engineering Review Comments
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entire length of the spillway. (Rev. 1) Addressed. As follow -up, label EC -3 matting on
sheet 4.
d. Due to the unusual geometry of the basin design, the inspectors are not able to verify plan
compliance and an as -built survey will be required upon completion of the sediment basin. The as-
built survey verification will be added to the SWPPP for review. (Rev. 1) Applicant response noted.
Request restated: Provide As -built to confirm sediment basin dimensions. Teardrop geometry
requires As- built. Final SWM facility occupies near identical footprint, and requires Construction
Record Drawing /As- built. Error in sediment /SWM basin construction may impact other properties.
(After note: initial comment reflects expert plan review experience. I rely on that experience.)
2. Please show the existing topography at least 50' past the property line and/or limits of disturbance for a
better understanding of the neighboring drainage patterns. Additional comments may arise from missing
information. (Rev. 1) Addressed.
3. Inlet protection should be shown on all inlets along Berkmar Drive that site may drain into. Appears there
might be 3 inlets that will need protection. (Rev. 1) Addressed.
4. New —sheet 3: Show existing gravel and pavement not to be removed/to be preserved. Ref. sheet 5,
plan/insets.
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 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 emails 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 request a pre - construction conference by completing a 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=cdengMTo
Thank you - 434.296 -5832 —x3069
WP0201500025_CMA Properties 081315 - revl.docx