HomeMy WebLinkAboutWPO201100070 Review Comments Erosion Control Plan 2011-12-16ALg�,��
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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: The Haven at Stonefield ESC Plan; WPO- 2011 -00070
Plan preparer: Mr. Herb White, PE; W & W Associates
Owner or rep.: Albemarle Place EAAP LLC
Date received: 29 August 2011
(Rev. 1) 16 November 2011
Date of Comment: 13 October 2011
(Rev. 1) 16 December 2011
Engineer: Phil Custer, PE
The ESC plan for the Haven at Stonefield (WPO- 2011 - 00070), received on 16 November 2011, has been
reviewed. The plan can be approved after the following comments have been addressed:
1. Similar to the comments made on previous ESC plans for Stonefield (WPO- 20 1 1 - 00037, WPO-
2011- 00055, and WPO- 2011 - 00060), this ESC plan must be a standalone application. The current
proposed plan relies on the northern sediment basin approved in the initial mass grading plan,
WPO- 2009 - 00074. Because there is a nine month timeline for all ESC plans, the mass grading
plan will need to be taken to the Board of Supervisors for an extension of the grading permit to
allow earth disturbing activities to continue (outside of reasonable building work areas). The nine
month expiration will occur on January 26`", 2012. To schedule a hearing on this extension, please
file a request to the clerk of the Board of Supervisors by November 23rd, 2011. If the Board does
not grant this extension to all of or portions of this plan, all plans relying on it may be invalidated
and a stop work order for all related construction will be issued until an amendment is approved
that meets state regulations. At that time, County Engineering may note that alternatives to
keeping the northern and southern basin online for more than nine months was possible, but was
not proposed by the applicant.
(Rev. 1) Comment has been noted by the applicant.
2. Sediment -laden water must not enter the permanent stormsewer system. A temporary pipe system
(TEMP -1) has been proposed from the corner of the site plan to EX 44. EX -44 to the pond is not
a temporary system and will be online indefinitely. Please extend TEMP -1 to the pond or outlet
into a diversion that takes the dirty water to the northern sediment basin. This pipe is to be
abandoned or removed once the site is stabilized.
(Rev. 1) Comment has been addressed.
3. The contractor will want to start on the construction of the footprint of each building as soon as
possible. Buildings E2 -I and E2 -II conflict with the diversions. Once the footprint of building E2-
II is in place, construction runoff cannot be directed to the temporary system; there will not be
enough room on site to maintain diversions on the north and east sides of building E2 -II. Building
E2 -11 should be constructed last after the county ESC inspector or County Engineer authorizes the
building permit. This can occur once all of the uphill inlet drainage areas are stabilized and clean
water is entering the permanent drainage system. Please place notes to this effect throughout the
plan. If the current concept is not working in the field, county staff may require that sediment
basin be constructed on the structure where the footprint of Building E2 -II is until the rest of the
site is stabilized. Please place notes to this effect throughout the plan.
(Rev. 1) All buildings are proposed to be constructed at the same time. The Phase H concept
proposed by the applicant in this submittal can be approvable with the following changes:
a. Please provide a diversion to the structure 115 sediment trap from the rear and top of
the retaining wall east of Building E2 -1.
b. Please provide dashed 83 contours to more clearly show an embankment for sediment
trap 115.
c. Please provide a small trap on structure 124. Structures 123 and 125 will have
overland flow relief.
d. Please remove the trap on structure 120.4 and add a trap on either 120.1 or 120.2 while
sealing the opposite one. Please also draw a diversion from the disturbance north of
G5 to this trap.
e. Please remove the trap on structure 131 and add a trap to structure 133 since it is the
low point of the area. Please callout structure 131 to be sealed until stabilization of its
drainage area.
f. Please provide maximum drainage area lines for each trap.
g. Please provide safety fence around all sediment traps.
4. The temporary pipe system discussed in comments 2 and 3 must be constructed after the
installation of the construction entrance. Please modify the construction sequence accordingly.
(Rev. 1) Comment has been addressed.
5. Please increase the diameter of the temporary pipe. Engineering review will consider this pipe as a
temporary slope drain since its function is to move construction runoff to a sediment basin. Table
3.15.A of the VESCH indicates that pipe diameter of around 36" will likely be necessary.
(Rev. 1) Comment has been addressed.
6. Please clearly note the sump on the temporary structure at the north east corner of the site.
(Rev. 1) Comment has been addressed.
7. Please include the construction of TEMP -1 within the limits of disturbance.
(Rev. 1) Comment is no longer necessary. This plan relies on the pipe and channel constructed
with the Town Centerplan (WPO -2011- 00059).
8. Please provide a RWD at structures 120.2 and 120.1 directing runoff into the existing diversion on
the north side of the site.
(Rev. 1) Comment has been addressed.
9. Please provide a completed Bond Estimate Request Form to the county engineer to receive an ESC
bond estimate. If the subdivision of this parcel occurs before the bond is posted, the owners of all
parcels disturbed will need to sign the bond estimate request and be party to the bond when it is
posted.
(Rev. 1) The ESC bond will be computed after comment 3 has been addressed.
File: E2_ecp_PBC _ wpo- 2011 -00070 Albemarle Place The Haven Apartments.doc