HomeMy WebLinkAboutWPO200800042 Review Comments Stormwater Management Plan 2008-11-07ALg�,��
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COUNTY OF ALBEMARLE
Department of Community Development
401 McIntire Road
Charlottesville, Virginia 22902 -4596
Phone (434) 296 -5832 Fax (434) 972 -4126
Project:
WPO- 2008 - 00042, Avon Court
Plan preparer:
Mr. Scott Collins, PE; Collins Engineering
Owner or rep.:
Avon Court Holdings, LLC
Date received:
23 April 2008
(Rev 1) 11 August 2008
(Rev. 2) 27 October 2008
Date of Comment:
6 June 2008
(Rev. 1) 3 September 2008
(Rev. 2) 7 November 2008
Engineer:
Phil Custer
(Rev. 1) John Diez
(Rev. 2) Phil Custer
fax 434.245.0300
fax (unknown)
The SWM, ESC, and road plans for Avon Court, received on 27 October 2008, have been reviewed. The
plans can be approved after the following comments have been addressed.
A. General Review Comments
1. For the ESC plan, construction operations appear to take place on TMP 77 -7. Please provide a
letter of intent from the property owner. The permanent easement on this property will be handled
through the ACSA review process.
(Rev. 1) Comment has been addressed
2. Please note that State Route 742 is Avon Road and not Avon Court. Please change this state route
number on all sheets.
(Rev. 1) Comment has been addressed
Please provide letters from the property owners of TMP 77 -9, TMP 77 -9A, and TMP 77 -8C
acknowledging that access to their site will be limited during the road construction operation.
VDOT approval may eliminate this comment.
(Rev. 1) Comment has been addressed
4. A letter of intent from the owner of TMP 77 -9A is needed for the construction of the parking lot
entrance.
(Rev. 1) Comment has been addressed
Stream buffers in the development areas are independent of the floodplain. Please adjust the plan
to correct this.
(Rev. 1) Comment has been addressed
6. Please amend note 1 on Sheet E -1 to match the floodplain note on the cover sheet.
(Rev. 1) Comment has been addressed
7. Please state the datum the topography was generated from on the plan.
(Rev. 1) Comment has been addressed
8. At Sta. 13 +50, there is a paved area with a culvert that is not shown or accounted for on this plan.
(Rev. 1) Comment has been addressed
B. ESC Plan Review Comments
1. Please provide adequate channels for all temporary and permanent discharge points. It appears
adequate channels are needed from trap #2 and the biofilter /trap #1. Easements will be needed
along these channels as well.
(Rev. 1) Comment has been addressed
2. Please provide a second construction entrance at the beginning of the work on Avon Court and
provide a note on the plan that this construction entrance is only to be implemented during the
construction of the roadway from Sta. 12 +50 to Sta. 18 +00.
(Rev. 1) Comment has been addressed
Silt fence on the southside of Avon Court is not an acceptable measure because it is placed across
contours. It appears that a diversion leading to a sediment trap would be a more appropriate
measure to treat this part of the construction. Please provide a letter of intent from the owners of
TMP 77 -8C to allow these construction operations to take place.
(Rev. 1) Comment has been addressed
4. Please state specifically on the ESC plan how the upgrade of the roadway between Sta. 12 +50 and
18 +00 will be carried out to minimize access issues to TMP's 77 -9, 77 -9A and 77 -8C.
(Rev. 1) Comment has been addressed
The post development drainage area to sediment trap #1 is greater than 3 acres and should be
designed as a sediment basin. The drainage area that I found using a planimeter was somewhere
between 3.5 to 3.75 acres depending on drainage line on a fully- constructed Avon Court that is not
shown correctly on sheet ESC -2.
(Rev. 1) Comment has been addressed
6. The graded slope northwest of sediment trap #2 needs an ESC measure.
(Rev. 1) Comment has been addressed
7. Please extend the diversion east of sediment trap #2 to capture the existing roadside swale
drainage. It appears that a grading easement exists in this area already.
(Rev. 1) Comment has been addressed
8. There are areas within the limits of disturbance that are not protected. Please amend the limits of
disturbance or adjust ESC measures to protect all disturbed areas.
(Rev. 1) Comment has been addressed
9. Will the concrete and waste areas located on TMP 77 -7 be removed with this plan? If not, please
clearly show the limits of construction and the existing concrete and areas to remain on the ESC
plan. If so, please provide protection measures for this work and a letter of intent from the
property owner.
(Rev. 1) Comment has been addressed
10. In trap 1, all slopes above the wet storage must be at least 2:1.
(Rev. 1) Comment has been addressed
11. Please adjust the calculation sheet of trap #2 to indicate the bottom dimension is 13' x 58'.
(Rev. 1) Comment has not been addressed
12. In all of the lots, please replace temporary seeding symbols with permanent seeding symbols.
(Rev. 1) Comment has been addressed
13. The ESC portion of the WPO bond will be computed once all comments have been addressed.
(Rev. 2) Comment remains unchanged.
14. Please note that a grading permit will be withheld until a copy of the state VSMP permit is given
to the county. Please contact Mr. Matthew Grant, DCR, at 804.225.3068 for more information.
(Rev. 1) Comment has been addressed
C. SWM Plan Review Comments
1. A signed Stormwater Management Facility maintenance agreement and recordation fee will need
to be submitted. Please contact Pam Shifflett (x 3246) for questions regarding this procedure.
(Rev. 1) Comment has been addressed
2. Engineering is only reviewing the SWM plan for the proposed construction of the extension of
Avon Court. There will be no future impervious area credit granted with this approval. On sheet
SWM -1, please remove the statement "It also demonstrates the ultimate development of the
parcels can achieve stormwater detention and quality." As always, the applicant may oversize
their facilities at his discretion but, as noted on the plan, additional SWM reviews will be required
for each future development plan.
(Rev. 1) Comment has been addressed
3. Please remove all "conceptual" stormwater management facilities and conveyance systems that
will not be constructed with this road from the calculations sheet.
(Rev. 1) Comment has been addressed
4. The downstream slope of the embankment should be constructed with 3:1 slopes.
(Rev. 1) Comment has been addressed
5. All slopes steeper than 3:1 will require a low maintenance, non - grassed groundcover. This
requirement is also enforced around biofilters.
(Rev. 1) Comment has been addressed
6. The SWM access road should be shown as 1Oft on the detail on SWM -2. Gravel is not required
unless the slopes are greater than 10%.
(Rev. 1) Comment has been addressed
7. The maximum ponding depth allowed in biofilters is lft. Please adjust biofilter elevations.
(Rev. 1) Comment has been addressed
8. Please change all callouts for Luckstone biofilter mix to "state approved mix."
(Rev. 1) Comment has been addressed
9. On the embankment detail, please show the cutoff trench into existing grade as it appears in Figure
3.01 -1a.
(Rev. 1) Comment has been addressed
10. Please provide a planting schedule for the biofilter. The planting plan should be designed
following the recommended specifications in the VSMH MS 3.11.
(Rev. 1) Comment has been addressed
11. It appears a permanent SWM easement will be needed on TMP 77 -7 for the underdrain. An
easement for this must be recorded before a grading permit will be given.
(Rev. 1) SWM easement is needed for level spreader. SWM facility maintenance agreement will be
needed for this property as well.
(Rev. 2) Please provide a letter from the owner of TMP 77 -7 allowing grading to take place on
their property. Also, no part of the level spreader can be located in the ACSA easement.
Maintenance of the ACSA easement may disrupt the level spreader and cause concentrated
flows.
Also, provide a detail and dimensions for the proposed level spreader in accordance with
Standard 3.21 of the VESCH.
12. The detention calculations do not appear to route the critical storm duration. I do not see how
there could not be any discharge from the bioiilter during the 2 -year and 10 -year critical storms. A
detention waiver could possibly be granted by the program authority. If desired, please submit to
me a justification letter citing any of the reasons listed in Section 17 -314G and I'll discuss the
issue with Glenn. On occasion, projects within close proximity to floodplains have been given
waivers for detention, but flooding of Moore's Creek is a well -known issue and a waiver may not
be granted in this watershed.
(Rev. 1) Comment has not been addressed. The facility has not been routed using the critical
storm. A storm with a longer duration and lower intensity would discharge water from the
facility. Our calculations indicate that the bioiilter detains the 2 and 10 -year storms to the pre -
development levels but it needs to be included in the plan set. Please contact Phil Custer at x3072
for further clarification.
In addition, the elevation -area table used in the computation is not representative of the basin as
graded between elevations 362 and 363. To correct, please use an increment of 362.99 with an
area close to 0.025acres.
(Rev. 2) The calculations are satisfactory.
13. The underdrain inlet elevation is incorrect.
(Rev. 1) Comment has been addressed
14.The SWM portion of the WPO bond will be computed once all comments have been addressed.
(Rev. 2) Comment remains unchanged.
D. Road Plan Review Comments
1. VDOT approval is required. Comments will be forwarded at the time they are received.
(Rev. 1) Comment has not been addressed
(Rev. 2) Comment has been addressed.
2. Please show all entranceways and parking lots of all of the sites affected by the road
improvements.
(Rev. 1) Comment has been addressed
3. Please provide horizontal curve information on the plan.
(Rev. 1) Comment has been addressed
4. Please provide marks at all +50 stations. [DM]
(Rev. 1) Comment has been addressed
5. Please show and label all traffic control signs on the plan.
(Rev. 1) Comment has been addressed
6. Please label all curb radii on the plan.
(Rev. 1) Comment has been addressed
7. Pipes 11 and 9 must be a minimum 15" in diameter.
(Rev. 1) Comment has been addressed
8. Please show outlet protection on the storm profile as well.
(Rev. 1) Comment has been addressed
File: E2_esc swm rp_JPD_08 -042 Avon Court