HomeMy WebLinkAboutWPO201400094 Review Comments WPO VSMP 2015-03-13 (3)�pF A
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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
VSMP Permit Plan Review
Project title: Whittington — Phase B
Project file number: WPO- 2014 -00094
Plan preparer: Dominion Engineering & Design, LLC
Owner or rep.: Piedmont Neighborhoods, LP, Stanley Martin Homes
Plan received date: 14 November 2014
(Rev. 1) 13 February 2015
Date of comments: 11 December 2014
(Rev. 1) 13 March 2015
Reviewer: Justin Deel, Glenn Brooks
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. 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.
1. Please use the standard template from the County website. You are presenting this as a revision to
expand an existing SWPPP. Your registration statement was for 184.1 acres, 75.4 of which was
disturbed. The new plans indicate phase A was 29.9 acres and phase B is 154 acres. Please clarify
the actual acreage disturbed, and all acreages on the documents. Please incorporate the active
SWPPP document, which this will replace in large part.
(Rev. 1) Comment partially addressed. The County template has not been used, please do.
2. Include only items in template and/or County Code Section 17 -405.
(Rev. 1) Comment not addressed. Stormwater calculations should not be a part of the SWPPP
document, please remove.
3. Provide any necessary TMDL measures.
(Rev. 1) Comment partially addressed. Your response to the comment needs to be incorporated
into the SWPPP document.
B. Pollution Prevention Plan (PPP)
The PPP content requirements can be found in County Code section 17 -404.
1. Please address all items listed in section 17 -404 of the County Code.
(Rev. 1) Comment partially addressed. Please follow the template. Use the index and
numbering system, so our inspectors know where to find items, and follow the instructions on the
template for content.
Engineering Review Comments
Page 2 of 8
C. 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.
It is unclear to us, and warrants further discussion, as to how your proposed stormwater
management plan stays within the approved ZMA plan. This may not be essential for the
grandfathering provisions in the state code, as DEQ already issued a permit for this activity.
However, the stormwater management needs to meet the IIC criteria, and at least provide the
coverage intent of the approved ZMA plan. There do not appear to be enough of the roadways and
houses captured by treatment. The original plan showed rain gardens in the cul -de -sacs and
intersections, and large ponds, with the intent to capture all of the roads, and the majority of lots
central to the development. The new plan leaves large stretches of road and lots untreated, with
grading that is problematic in providing permanent capture to the BMP facilities. Please revise to
provide follow the natural drainage of the topography. Coordinate to provide adequate sediment
trapping for erosion and sediment control, along natural topography, outside limits of final lot and
road grading, and coordinated for conversion to permanent stormwater management.
(Rev. 1) Comment not addressed. An overall stormwater management plan is not found in this
plan set. In order to approve what you are proposing in your response, an overall stormwater
management plan(s) must be provided showing each SWM facility with its respective clearly
defined drainage area. We need to see what areas you are proposing to treat and what areas will be
left untreated. We need to see that you are in general accord with the rezoning plan. Specifically,
an attempt must be shown to capture and treat the areas that are shown as being treated in the
rezoning plan.
Please refer to supplemental comments provided by the County Engineer.
2. Please provide proposed mapping and plans, showing drainage areas for proposed stormwater
management facilities, at a legible scale (preferably at least 1" = 50').
(Rev. 1) Comment addressed.
3. Show stream/wetlands buffer at SWM- 3 /SB -1 and add mitigation accordingly.
(Rev. 1) Comment addressed.
4. Provide sediment forebays in all SWM facilities [VSMH Vol. 1, 3.04].
(Rev. 1) Comment not addressed. SWM 5 & 8.
5. Provide measures to avoid short- circuiting in SWM -3 and SWM -7 [VSMH Vol. 1, 3.06- 12 -13].
The basins should meet the flow and shape design parameters. (Baffles should not be a part of
permanent designs.)
(Rev. 1) Comment partially addressed. The one -foot earthen embankments will not be adequate
or practical in avoiding short- circuiting and cannot be used. There is room to grade differently and
reposition the primary spillway.
6. Provide facility access per VSMH Vol. 1, 3.06 -18.
(Rev. 1) Comment partially addressed. Show access to SWM -4.
7. Existing topography is not labeled on some SWM facility details, please correct.
(Rev. 1) Comment not addressed.
8. Show accurate existing topography for SWM -4.
(Rev. 1) Comment addressed.
9. Provide scaled cross sections for SWM facilities, including biofilters, in place of old typical details
(E43).
(Rev. 1) Comment partially addressed. Show crest elevations on all SWM details. Provide note
concerning dam core and compaction on sections. The old typical biofilter details and sections
Engineering Review Comments
Page 3 of 8
cannot be used, please remove these and provide only actual details and sections.
10. Please remove Proffered Overlot Grading Plans. They appear to be largely redundant in this plan
set. Grades should be shown anyway as part of an E &S /SWM plan package. The overlot grading
plan is a zoning requirement as part of the proffers, which are not enforced through the VSMP
program.
(Rev. 1) Comment addressed.
11. The County BMP spreadsheet is no longer acceptable. Designs must follow the state IIC or IIB
criteria.
(Rev. 1) Comment addressed.
Revision 1 Comments:
12. Slopes leading in to your basins are too steep. Any basin should have maximum 3:1 slopes for
maintenance and safety [VSMH Vol. 1, 3.01 -13]. Please reflect this on your plans, details, and
sections.
13. Please provide SWM facility type in your details (Basin I, H, Bio- Retention).
14. Show all facility structures in plan details, see riser in SWM -6 detail.
15. Show proposed contours west of retaining wall at SWM -3.
The computation package, included as an appendix to the SWPPP, could not be reviewed
adequately, because it could not be correlated to the plan set, and we anticipate changes to the
overall concept.
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, 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. Please explain how your phasing plan (E3) will be implemented. It appears as though the
installation of the sanitary sewer line will warrant E &SC measures that will not occur until
subsequent phases.
(Rev. 1) Comment addressed.
2. Mitigation for disturbance to stream buffers should occur within the affected stream buffer, please
correct [Albemarle Co. Code 17 -604 C.5]. Mitigation can occur in other stream buffer areas, but
mitigation is not valid outside stream buffers unless it is additional stormwater treatment for
discharging into buffers.
(Rev. 1) Comment not addressed. Mitigation should occur within the WPO buffer within this
subdivision.
3. Your wetlands report shows a wetland in the areas of SB -1 and SB -3. Please provide a stream
buffer for these areas and include in your mitigation plan.
(Rev. 1) Comment addressed.
4. Grading for SB -3 affects a stream/wetland that is not within your stream buffer. Please explain
why this is not included in the buffer.
(Rev. 1) Comment addressed.
5. Please explain why the northwesternmost stream on the property is excluded from your shown
stream buffer.
(Rev. 1) Comment addressed.
6. Please adjust your limits of disturbance to include all affected areas, not just the areas that are to be
graded.
(Rev. 1) Comment partially addressed. There are still "gaps" in your limits of disturbance that
Engineering Review Comments
Page 4 of 8
will receive sediment. Tree protection alone will not leave these areas unaffected by erosion and
sediment.
7. Provide staging /stockpile area(s).
(Rev. 1) Comment partially addressed. These areas require E &SC measures.
8. Show dust control and temporary /permanent stabilization.
(Rev. 1) Comment addressed.
9. Please do not show silt fencing going down/up hill. Silt fencing should be "stepped down ".
(Rev. 1) Comment partially addressed. The stepped down silt fencing looks good in some areas
but other areas require more adequate steps.
10. Silt fencing should not be used in place of diversion dikes. Please provide diversion dikes and/or
sediment traps where needed (Ex.: the silt fence traversing the southern portion of Sheet E21).
(Rev. 1) Comment partially addressed. There are still several areas (see Revision 1 comments
below) that need diversion dikes leading to traps or basins.
11. Provide legible drainage areas on E &SC plans. The provided drainage area maps are unclear and
several are unrealistic (Ex.: Drainage area for ST -12).
(Rev. 1) Comment addressed.
12. Please show topography for the entire drainage area at ST -16. It appears as though the ridgeline
may be beyond your drainage area.
(Rev. 1) Comment addressed.
13. Culvert designations vary on E &SC plans and drainage plan (E31), please correct.
(Rev. 1) Comment addressed.
14. Please show realistic shapes for sediment traps and basins (Ex.: ST -1).
(Rev. 1) Comment not addressed. Our recollection of the discussion was that the shapes of the
sediment traps and basins should be realistic; ST -1 & ST -15, for example, are not. Realistic
shapes are close to a square, circle or equilateral triangle, and do not have narrow protrusions or
turns, which tend to not be constructed, or to collect sediment unevenly, harming functionality.
Also, you are showing multiple proposed grading lines in several sediment traps, please clean this
up (Ex. ST -11, -19, -20).
15. Provide a construction entrance that drains to a sediment trap or basin [VESC Handbook, 3.02].
(Rev. 1) Comment not addressed. How are you proposing that the CE will drain to SB -2? Is
there an existing cross drain that is not shown? Otherwise, there should be a RWD. Also, the CE
is not shown in Phase 2, please correct.
16. Show critical slopes on E &SC plans.
(Rev. 1) Comment not addressed.
17. Show proposed Phase 1 topography as existing topography on Phase 2 plans. Ideally, phase A/1
areas are already graded, and topography should be resurveyed in these areas.
(Rev. 1) Comment addressed.
18. Show existing topography for Phase A.
(Rev. 1) Comment addressed.
19. Please provide an explanation for your "Phasing Plan ", Sheet E3.
(Rev. 1) Comment addressed.
20. Include proposed sediment basin at Phase B entrance in your limits of disturbance. Please show
existing topography and provide a designation for this basin.
(Rev. 1) Comment addressed.
21. Provide detail for CWD, these are not a part of the VESC Handbook.
(Rev. 1) Comment addressed.
22. The CWD above the cut on Sheet E 14 should follow limits of disturbance to avoid high velocity
flow into wetland, please adjust.
(Rev. 1) Comment not addressed. This diversion has not been changed, rather the wetland is
now being shown as ephemeral stream. I see that this reflects the provided updated report by TNT
Engineering Review Comments
Page 5 of 8
Environmental. However, high velocity flow should be avoided here whether this is wetland or
ephemeral stream. Please correct. Perhaps the diversion should lead to ST -11, which would need
to be resized.
23. Anywhere silt fence or diversions are coming to a point at a natural drainage low spot, a sediment
trap or basin must be provided. As an example, provide a sediment trap for the fill slope between
STA 21 +00 and 20 +00 on Sheet E5.
(Rev. 1) Comment partially addressed. Additional sediment traps and diversions are need
throughout the site, see Revision 1 comments below.
24. Provide sediment trapping measure in front of Lot 26.
(Rev. 1) Comment addressed.
25. Provide more effective E &SC measures at stream crossings.
(Rev. 1) Comment partially addressed. Sediment traps at stream crossings should be moved
further out of WPO buffers. In most cases, the sediment traps will need to be moved into the
proposed home lots. There should be a note on the plans saying that the building permit for these
lots cannot be issued until E &SC until a County inspector authorizes removal of E &SC measures.
26. Provide a sediment trap for the fill slope at the end of Kentra St., Phase 1.
(Rev. 1) Comment partially addressed. This trap needs to remain in place for Phase 2.
Additional E &SC measures (sediment traps) are needed at lots 39 and 40 as well.
27. Show how drainage on Sheet E12 will reach ST -7.
(Rev. 1) Comment addressed.
28. Please show access easement for Singleton Lane.
(Rev. 1) Comment addressed.
29. Provide scaled details (sections) for basins.
(Rev. 1) Comment partially addressed. Please provide both existing and proposed grades on
sections.
30. Please clarify what you are proposing at ST -14, Phase 2.
(Rev. 1) Comment addressed.
31. Please provide adequate E &SC measures to protect WPO buffer. More than silt fencing will be
required to protect WPO buffer in many areas.
(Rev. 1) Comment partially addressed. Please see Revision 1 comments below.
32. Provide E &SC measures, other than silt fencing, beneath fill slopes east of Kendra St., especially
lot 39.
(Rev. 1) Comment not addressed. See comment 26.
33. Ensure that all sediment basins outfall into an adequate channel.
(Rev. 1) Comment addressed.
34. Is ST -13 not included in Phase 2? It appears as though it is needed and is included in Phase 2
drainage area map, but not in Phase 2 plan.
(Rev. 1) Comment addressed.
35. Please make sure all existing and proposed contours are labeled on all plan sheets (Ex.: Proposed
contours on Sheet E 13 are not labeled, existing and/or proposed contours are not labeled on many
of the sediment basin/trap details.
(Rev. 1) Comment not adequately addressed. See proposed contours on Sheet E22. Additional
contour labels are need throughout these plans, existing and proposed.
36. Further, please ensure that all structures and embankments match permanent design for facilities to
be converted to permanent stormwater management facilities.
(Rev. 1) Comment addressed.
37. Diversion dike cannot go through home lots. As stated in the stormwater management comments,
please ensure all protection measures are outside lot and road grading where ongoing maintenance
is not possible. Perimeter protections must be on the perimeter.
(Rev. 1) Comment addressed.
Engineering Review Comments
Page 6 of 8
38. Silt fence alone is not adequate enough on and around Lot 28, please correct.
(Rev. 1) Comment not addressed. There are no E &SC measures to prevent stream buffer
disturbance from the grading of this lot.
Revision 1 Comments:
39. Ensure that sediment traps/basins in Phase 1 are designed for drainage areas increase with Phase 2.
40. Many of your sediment traps and basins need diversions leading to them (SB -1, SB -4, ST -12, and
others).
41. The limits of disturbance around the CWD at around elevation 620' (Sheet E5) are unrealistic and
need to be adjusted. Is this being removed in Phase 2? Please clarify.
42. The diversions leading to ST -19 should remain in place in Phase 2, please correct.
43. More sediment traps and diversions are needed to protect the WPO buffer on both sides of
Cottontail Way. Silt fencing alone is not adequate. For example, Lot 23 needs diversions leading
to a trap in the swale, as does the open space between Lots 27 & 28.
44. Silt fencing is needed to protect the stream buffer east of SB -1. Tree protection alone will not
leave this area undisturbed.
45. Diversions leading to a sediment trap are needed between Lots 43 & 44, please provide.
46. Provide silt fence and/or diversions behind Lots 11 & 12.
47. Drainage should not traverse more than 3 home lots without a sediment trap (Ex. Most of Kendra
Street), please correct.
48. Diversions and more silt fence are needed to protect WPO buffer at the back of the lots along
Kendra St.
49. A sediment trap(s) is needed at Lots 38 & 39, and 68 &69, please provide.
50. Diversion dikes leading to a sediment trap are needed along the back of the proposed lots on the
south side of Warbler Way, please provide.
51. More than silt fence is needed to protect the WPO buffer at Lot 73.
52. ST -13 needs to be at the base of the slope with diversions leading to it.
53. Provide silt fence between SB -3 &4 and the WWO buffer, there are labels in place but not drawn.
54. Provide silt fence at SB -2.
55. Please clarify SB -5 grading on Phase 1 & 2 plans. Also, you are showing the basin outfalling into
a sediment trap in Phase 2. The basin should be located where this trap is located. Please correct
and clarify this.
56. The riser /outfall at SB -1 should be placed in a location that would avoid short- circuiting.
57. Your sediment trap spillways are too small and are unrealistic, please correct. A practical limit
with rip -rap is about 6 feet.
58. The diversion dike around ST -11 is unrealistic in that we feel it will be impractical to construct
and inadequate, please address. This ties in with the italicized comment below concerning your
phasing approach.
59. A variance is required for each proposed MT and CWD.
60. There are multiple proposed contours for ST -11, 19, & 20, please clarify.
61. Please be consistent with DD /CWD line weights. Some are enormous while others are difficult to
see. See Sheet E5.
Note: Due to the above requested changes, sediment trap/basin sizes have not been verified with this
submission, and will be checked with the next revision.
Please refer to supplemental comments provided by the County Engineer.
Engineering Review Comments
Page 7 of 8
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 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 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;
hqp://www.albemarle.org/deptfonns.asp?department--cdengno
Engineering Review Comments
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File: Whittington Phase B WPO201400094 R1.doc