HomeMy WebLinkAboutWPO201400077 Review Comments WPO VSMP 2014-12-19� OF AL
,. vIRGINIP
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 rile number:
Plan preparer:
Owner or rep.:
Plan received date:
Date of comments:
Reviewers:
VSMP Permit plan review
Rivanna Village Phase 1
WP0201400077
Santec
RIVANNA VILLAGE LLC
3 December 2014
19 December 2014
Max Greene, Glenn Brooks
[scott.blossom@ stantec.com]
[ANDREW.BONINTI@ CBRE.COM]
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. The rationale is
given in the comments below. The application may be resubmitted for approval if all of the items
below are satisfactorily addressed. No additional fee is required for resubmittal. 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 SWMP, and (4) any TMDL measures necessary.
1. The registration statement appears to be in error. The land development is listed as 94.66 acres and
disturbed area as 40.93. The plans submitted show 58.8 acres "project limits" and 36.5 acres
disturbed. The registrations statement and SWPPP will only be permitted for areas with approved
plans.
2. Plans included with the SWPPP must be approved plans. The SWPPP includes a "Preliminary
Stormwater Concept" plan. This does not appear to have been included with ZMA201300012 or
earlier plans, and so does not appear to have any official standing. It should not be part of the SWPPP.
3. Include an explanation of the staging and phasing in the SWPPP. The concept of a stage 3, in which
the ultimate development is not considered per 9VAC25- 870 -72, presents some difficulties, and we
will have to run this by DEQ personnel for guidance.
4. Please follow the standard Albemarle County SWPPP template. Including more is fine, but it should
at least have the template items.
A. Pollution Prevention Plan (PPP)
The PPP content requirements can be found in County Code section 17 -404.
Please provide a pollution prevention plan as part of the SWPPP. Label it clearly, and provide a site
layout plan with pollution prevention measures located on it to start.
B. Stormwater Management Plan (SWMP)
VSMP Regulation 9VAC25- 870 -108 requires the VSMP authority to approve or disapprove a SWMP.
This plan is disapproved, and the reasons are provided in the comments below. The stormwater
management plan content requirements can be found in County Code section 17 -403.
1. Provide the VRRM spreadsheets for each section of the site. A full review could not be completed, as
these were not included in the submittal. Please ensure that the areas used in the computation, both for
Engineering Review Comments
Page 2 of 5
drainage to each facility, and for disturbed area load computations turf, forest, and impervious, appear
on a plan sheet or map.
2. Where preserved/forested areas are credited in the computations, there must be temporary physical
barriers and permanent easement measures provided to ensure they remain undisturbed.
3. The "project limits" shown on plans are confusing. It is unclear what they represent, as the limits of
disturbance, parcel boundaries, and drainage areas appears to provide what is necessary.
4. The stormwater plan seems to have temporary measures still shown, like construction entrances,
temporary stream crossings, silt fence, haul roads, and diversions. Notes even indicate temporary
perimeter measures to remain. Temporary measures should be finished, removed, and the site fully
stabilized/vegetated for the stormwater management phase. Grading and formal channels should be
provided to direct drainage if necessary rather than temporary diversions.
5. Uncollected areas will need to be accounted for in the load computations.
6. Provide planting plans, or typical areas to be repeated when planting within each facility. It is unclear
how the tables are to be implemented.
7. Keep to standard engineer scales. (i.e. not 70)
The site seems to be divided into four main areas, outlined in the graphic below, and only limited detailed
review could be provided without the load and load area computations. Facility sizing and removals
could not be checked at this time.
-
[caMa
Ewen
ncnmE
i
90\ 4
Area 1:
1. The wet Swale needs a water source for the new wetland. The existing wetlands have the stream. The
proposed wet swale appears to sit 6 feet above on constructed fill.
2. Bioretention basins have a maximum drainage area of 2.5 acres. Please adhere to the guidelines in the
Engineering Review Comments
Page 3 of 5
state specification. The proposed bioretention has 8 acres drainage too it, which is too large.
3. Grass channel AS3a -1 is too steep and not wide enough. Please adhere to the guidelines in the state
specification.
4. Provide sections and details for each grass Swale.
5. Contributing drainage areas to the swales appear incorrect. The full drainage area cannot simply be
split with half going to each grass Swale, as much of the area appears to drain directly to the basin.
Please adhere to the guidelines in the state specification; 5 acres maximum.
6. Remove the haul road which goes directly over the ditch and diversion on the east side of the basin.
This is unmanageable.
7. Biofilters/basins should have forebays and energy dissipation /spreaders at concentrated inflows.
8. The proposed grading does not appear to tie in correctly at points on this plan, and clearly goes outside
limits of disturbance. Correct the grading.
9. Label and dimension the facilities on the cross sections.
10. Provide riser details and dimensions on the cross - sections, and provide anti - clogging measures.
11. The dam should be 3:1 or flatter on the downstream face. Dimension heights and top widths.
12. The underdrains need to be installed in the gravel layer below the media in any biofilters, and cleanout
must be provided.
13. Sheet 14 standard details are confusing, as they don't match the cross - section details. If the specific
sections and plans are done correctly, these generics should not be needed.
14. On the cross - sections, remove the sub - surface EC -2 matting. This should be a surface application for
stabilization.
Area 2:
1. The basin contributing area is too large. Please adhere to the guidelines in the state specification.
2. The wet swale does not appear to have a water source.
3. See cross - section comments for Area 1. Most apply here.
Area 3:
1. The wet Swale does not appear to have a water source.
2. CS3a contributing drainage area is too large, and the other 2 channels are too narrow, and too steep in
sections. Please adhere to the guidelines in the state specification.
3. Please adhere to the guidelines in the state specification for the wet pond. The wet pond does not have
the minimum contributing area and appears to be excavated next to a stream. Physical testing of the
groundwater table is required for design. If it interferes, the pond may not achieve adequate water
quality removal according to the spec. 3:1 slopes on downstream faces must be provided uniformly.
The wet pond does not meet the type 2 criteria. It must have multiple cells and wetlands. Slopes
leading to the water should be 3:1 or flatter and a safety shelf provided. The geometry is not adequate
for shortest flow path. Provide an emergency spillway or adequate freeboard.
4. The detail on sheet 16 appears to be for a temporary riser setup. Please correct, and add these details
to the cross - section.
5. It is unclear how the planting table on sheet 10 is to be incorporated on the plan.
6. Please remove rip -rap rather than compacting into fill on dams, which appears as though it could leave
a water conduit through the structural fill if not done very well.
7. See cross - section comments for Area 1 -2. Most apply here.
Area 4:
1. Please do not include off -site areas which can be diverted. These areas may change in the future,
affecting results.
2. Please see comments for areas 1 -3, many apply here.
Engineering Review Comments
Page 4 of 5
C. Erosion and Sediment Control Plan (ESCP) Max Greene's comments
Virginia Code §62.1- 44.15:55 requires the VESCP authority to approve or disapprove an ESCP. This
plan is disapproved, and the reasons are provided in the comments below. The erosion control plan
content requirements can be found in County Code section 17 -402.
1. Match lines would be helpful to the inspector /contractor.
2. All proposed grade lines will be within the limits of disturbance.
3. There appears to be a basin proposed on sheet 8 of 9 on the bottom of the page across from the
Glenmore entrance. There is no outlet for this sump area. Please explain.
4. Silt fence is shown very close to the edge of stream. Please place a note on the plan sheets "Silt
Fence and Diversions will be kept a minimum 5' from top of bank. If a discrepancy occurs in
the field for silt fence and/or diversion installation then the plans will be amended to reflect the
changes required to keep the silt fence and or Diversion a minimum 5' from top of stream
bank."
5. Silt fence should follow contours. Low points in silt fence are pounding areas and tend to fail from
excessive collection of water and silt. Traps may be required "in field" should these areas show
potential for failure. Project delay could occur if a new plan is required for field adjustments.
"Operator" will need to be proactive to prevent delays.
6. Silt fence installed down a slope is essentially a diversion and tend to cause erosive velocities and
blow -outs in low points of silt fence. If silt fence must be utilized down slopes then check dams
should be installed to slow the velocities and to force the stormwater through the filter fabric. (See
note #3) Diversions are recommended for down slope installations.
7. Temporary Stream Crossings do not appear to be adequately addressed.
a. Please Refer to VESCH Std. & Spec. 3.24 Temporary Stream Crossing (SC) Design Criteria
Page III -221 note d for diversion requirements.
b. Please add VESCH Std. & Spec. 3.24 Temporary Stream Crossing (SC) Construction
Specifications "Temporary Bridge Crossing" to the plan.
8. Please place a note on the plans: "Silt fence will NOT be installed across the outlet of any
stormwater detention structure. Pipe Outlet: Silt fence shall be installed over the outlet of pipes.
Stone Weir: Silt fence shall be turned up slope on either side of weir outlet.
9. Limits of disturbances appear to include sanitary sewer installation limits. Early grading does not
allow for the installation of sanitary sewer lines or other hardscape. Please remove the limits of
construction for infrastructure such as sanitary or storm sewer line installation.
10. Proposed silt fence appears to have an existing swale intersecting perpendicular to the silt fence. The
silt fence directs the storm flows to the low point in the corner adjacent to the wetland area. A
diversion and trap should be shown in this location instead of silt fence.
11. Sediment basin AS1a is missing the outlet structure and riser pipe on plan view. (Page 7 of 19)
12. Proposed diversion ASIa appears to have an existing swale intersecting perpendicular to the diversion
and is also the low point of the diversion. Stormwater will not make it to the basin as shown until the
fill material is placed. Please show a temporary trap in this location. (Pages 7 of 19)
13. Silt fence and fill material appear to encroach on existing swale at the top of page 10 of 19. Swales
should not be blocked with silt fence. A sediment trap is recommended in this area; otherwise, pull
the proposed grading toe of slope back to top of 2 year storm elevation for swale to prevent erosive
undermining of silt fence.
14. Erosion control measures are not shown for East side of sediment trap BS2b along limits of
disturbance. (page 10 of 19)
15. Silt fences and diversions on Stage 2 plans sheets have all most disappeared from view like the
existing contours. Please make sure the shading of E &SC measures that are to remain are clearly
recognized on the plan sheets.
16. Proposed travel ways that cross over a diversion will require a pipe or other State approved method
designed for the 10 year storm event.
Engineering Review Comments
Page 5 of 5
Additional comments and /or conditions may be forthcoming due to requested changes to plan.
The VSMP permit application and all plans may be resubmitted for approval when all comments have been
satisfactorily addressed. For re- submittals please provide 2 copies of the complete permit package with a
completed application form.
Engineering plan review staff are available from 2 -4 PM on Thursdays, should you require a meeting to discuss
this review.
Process;
After approval, plans will need to 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 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 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;
httD:// www.albemarle.or2/deDtforms.aSD ?department= cden2wno
File: E1_vsmp_review_projectname.doc