HomeMy WebLinkAboutWPO201100059 Review Comments Erosion Control Plan 2011-10-20ALg�,��
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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: Stonefield Town Center ESC Plan; WPO- 2011 -00059
Plan preparer: Mr. Herb White, PE; W & W Associates
Owner or rep.: Albemarle Place EAAP LLC
Date received: 11 August 2011
(Rev. 1) 17 October 2011
Date of Comment: 29 September 2011
(Rev. 1) 20 October 2011
Engineer: Phil Custer
The second submittal of the ESC plan for Stonefield Town Center (WP0- 2011 - 00059), received on 17
October 2011, has been reviewed. The plans can be approved after the following comments have been
addressed:
1. Similar to the comments made on previous ESC plans for Stonefield (WPO- 2011 -00037 and
WPO- 2011 - 00055), this ESC plan must be a standalone application. However, this plan cannot
help but rely on the sediment basin constructed with the mass grading plan (WPO- 2009 - 00074)
until the site is almost entirely stabilized. 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`h, 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.
(Rev. 1) Comment has been acknowledged by the applicant.
2. The ESC plan for this project will need to be at least three sheets:
-a sheet showing what the site will look like with proper protections on the day a grading permit is
issued (Route 29 and Hydraulic Rd improvements, Swanson Rd., Stonefield Blvd., and Regal
Cinema work areas completed)
-a sheet showing what the site will look like on the day before the sediment basin will be filled in
(including the size and location of the soil stockpile); on this sheet, please include a note stating
that the sediment basin shall not be removed until permission is given by the county E & S
inspector
-a sheet showing the necessary protection measures /construction area to construct the areas not
stabilized in the previous sheet.
The basin cannot be removed until the majority of the site (everything but the basin and stockpile)
is stabilized with grass, roof, building pad, or gravel.
(Rev. 1) The project has been project out into the phases as requested. Please make the
following changes to the plan:
-In Phase 3, please remove all inlet protection on inlets that are in areas assumed to be
stabilized. Every inlet drainage area other than those in the northern parking lot must be
stabilized with cleanwater running to the detention facility in Phase III.
-In Phase 3, please show a limits of disturbance line around the work area (east of District
Avenue, north of Bond Street). The rest of the site should not need to be disturbed.
-In Phase 3, the drainage area of trap 72.4 will be larger than 3 acres. This settling facility will
need to treat from Stonefield Blvd. to Route 29 north of buildings B -I, B -II, B -III, and C2 -II.
By my calculations this area is close to 4.5 acres. A basin should be cored into structure I of
WPO- 2010 -00023 as the ground around it (its embankment) is constructed. A diversion should
be extended to the slip ramp to capture as much of this road as possible (as the plan currently is
doing).
- Remove all proposed hardscape lines from Phase 2 that must be constructed in Phase 3.
-The bottom of the slip ramp next to the Sperry Marine property looks to be an area of possible
blowout. Please address. Can the pipe going to inlet 85 be exposed with CIP on it?
3. The site is graded /will be graded in such a way that runoff would likely end up in the Route 29
ROW (at the east end of Main Street). This plan must address this concern. It seems that the 6ft
diversion ditch, SCC1 on WPO- 2009 - 00074, could be extended to structure 79 and kept on the
plan (illustrated phase 2 as referred to in the previous comment) as surrounding infrastructure and
buildings are completed.
(Rev. 1) Phase 2 of this plan shows a graded diversion up to Main Street with the utilization of
a ROW diversion across this travelway. This is not acceptable. Please extend the grading of a
3ft deep diversion to structure 79. Much of the Main Street Entrance that appears on the Route
29 and Hydraulic Road Plans should not be built until Phase 3. After discussions with the
VDOT engineer, it appears construction can realistically stop about IOft into the site from the
flow line between structures D -2A and D -3A. The diversion's depth should be established by
cutoff of the contours from the Route 29 ROW and should not rely on fill. A trap at structure
79 is no longer necessary.
4. Sediment -laden water must not enter the permanent stormsewer system and detention facilities.
Inlet protection is more often than not an inadequate measure because the inlets are constructed
well after initial land disturbance. Even after installation, storm inlets are often bypassed because
their rim elevation is higher than the subbase and gravel around them until the final stage of
construction. Please make it clear throughout the plan that construction runoff is not to enter the
permanent drainage system.
Engineering review is especially concerned with the two sump conditions in the south eastern
parking lot and the grate inlets along Bond Street. A sediment trap inlet protection will likely be a
solution on structure 82. The diversion, SCC1, shown on the mass grading plan (WPO -2009-
00074) can be extended to structure 79. The grate inlets on Bond Street can be sealed until the
county inspector has confirmed the drainage area is stabilized.
The hotel construction area has a similar construction issue as the western parking lot for the
cinema plan had. To keep sediment -laden runoff out of the permanent drainage system and
Stonefield Blvd. ROW, please keep the temporary pipe system approved in the WPO- 2009 -00074
active and direct this construction area to this system with diversions on the east and north ends of
the hotel construction area. These diversions and temporary pipe system can be removed (or
abandoned) once the county ESC inspector has determined that the hotel area is stabilized. A
more advanced inlet protection on structures 110 and 112 will be needed since these inlets are in
sump. Perhaps a sediment trap inlet protection, similar to sediment trap culvert inlet protection,
could be designed at these structures. The grading for such a measure would need to be shown
and designed as a sediment trap.
(Rev. 1) As directed in Comment 3, please extend the diversion ditch in Phase 2 to Inlet 79.
The switch from 50 scale to 100 scale makes the review of the rest of this comment difficult.
Please make the following modification to the plan:
-In Phase 2, by the hotel site, please provide notes in several areas that sediment laden water is
to be directed to structures 21 and 20. Please identify that these inlets are not to have inlet
protection and specify the sump for each.
- Please identify the pipe that was added to the Regal Cinema ESC plan to the south for the
construction parking lot on the west side of District Avenue.
-In the same note as the one that talks about the use of flowable fill in TEMP -1, please state
that when the hotel site is stabilized and the permanent drainage system has been turned online
that these pipes are to be filled with flowable fill.
Please show the updated grading with the Route 29 and Hydraulic Road improvements on the
phase it is expected to be completed. The county is most concerned with how the Route 29 turn
lane and Main Street entrance from Route 29 affects the eastern diversion shown on WPO -2009-
00074. Please also see comment 3.
(Rev. 1) Please refer to Comment 3.
6. Please show the soil stockpile on each phase of the plan. Please also refer to comment 2.
(Rev. 1) Comment has been addressed.
7. Please place a construction entrance on Swanson Drive at Hydraulic Road and include it in the
limits of disturbance. It seems unreasonable that traffic flow to the theater can be maintained
through this entrance considering the significant construction traffic. Other construction entrances
on Main Street east of Stonefield Blvd., into the hotel parking lot from Stonefield Blvd., and First
Street west of Stonefield Blvd. are recommended.
(Rev. 1) Comment has been addressed.
8. Please show a diversion /fill diversion at the top of the slope south of the southern Sperry Marine
boundary line.
(Rev. 1) Comment has been addressed.
9. Please show silt fence on the southern limits of disturbance of the hotel site.
(Rev. 1) The silt fence should be shown in the Phase 2 sheets because the site is graded to the
south in this phase. In phase 1, the hotel site drains to the northeast.
10. The construction of Second/Third Street will either need its own sediment trap or basin north of
the intersection with Stonefield Blvd. or a ditch from the construction area to the sediment basin
approved WPO- 2009 - 00074. Please note that the use of this facility will be conditioned on Board
approval as explained in comment 1. Engineering staff will likely note that a new sediment trap or
basin for this construction area for this road (and the Haven) is a practical solution.
It is also recommended that the construction of this road be removed from this plan and included
in the Haven ESC plan which was recently submitted because the Haven will likely need an
independent sediment basin north of this intersection as well.
11. (Rev. 1) A temporary pipe system (TEMP -1) has been proposed from the intersection of
Blackbird Lane and District Ave. 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. Please also 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.
12. Please update the construction sequence as necessary to account for changes to the plan required
by the above comments.
(Rev. 1) Please continue to update the construction sequence based on modification necessary
to address comments 2, 3, and 4.
13. Please include the amount of total land disturbance shown on this plan.
(Rev. 1) Comment has been addressed.
14. If a temporary construction trailers are necessary, they will likely need to be shown on an approved
ESC Plan.
v. 1) Comment has been acknowledged by the applicant.
15. Please provide a completed Bond Estimate Request Form to the county engineer to receive an ESC
bond.
(Rev. I) A completed Bond Estimate Request Form has been submitted. Bond estimates will be
provided after all WPO comments have been addressed.
File: E2_ecp_PBC _ wpo- 2011 -00059 Stonefield Town Center.doc