HomeMy WebLinkAboutWPO200800091 Review Comments Erosion Control Plan 2008-10-21� OF AL
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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 - 00091, SDP - 2008 - 00134; The Meadows Expansion
Plan preparer: Brian Smith, PE
Owner or rep.: Jordan Development Corporation
Plan received date: 09 September 2008
Date of comments: 21 October 2008
Reviewer: Phil Custer
The major site plan amendment, SWM, and ESC plans for The Meadows Expansion, submitted on
9 September 2008, have been reviewed. The plans cannot be approved as submitted and will
require the following changes:
A. General Review (SDP- 2008 - 00134)
1. To engineering review, there appear to be several discrepancies between this plan and the
approved rezoning plan. The discrepancies are listed below:
A. The rezoning plan states that biofilters will be used on site. No biofilters were provided in this
site plan amendment.
B. The location, orientation, and parking of building 8 do not match.
C. In the application plan, a yard was proposed between buildings 10 and 11. SWM facility 2 is
currently proposed in that location.
D. SWM facility 3 has been placed in an area reserved for a future interparcel connection. This
facility should be relocated.
The Planning Department will need to determine whether the plan is consistent with the approved
rezoning plan. If it is found to be not in general accord with the plan, a determination must be
made by the Zoning Department whether these deviations from the approved ZMA plan can
possibly be approved through a variation by the Director of Planning.
2. Please provide the date of the topographic survey.
3. Please show the stream buffer lines on all applicable sheets.
4. VDOT approval is required. VDOT approval has not been received at this time. As indicated in
the rezoning plan, a left turn lane on northbound Crozet Avenue may be required.
B. Major Site Plan Amendment (SDP- 2008 - 00134)
1. Slopes steeper than 3:1 require a low maintenance, non - grassed groundcover.
2. Please show all necessary signage.
3. Concentrated discharge appears to be running across several sections of the walking path/sidewalk.
Engineering review recommends that the walking path be placed uphill of the outfalls for Basins 2
and 3 and a drop inlet to be added at the northern corner of building 20 to prevent direct
stormwater discharge across these pedestrian areas.
4. Please provide a channel from the existing culvert west of building 8 around the fill for the parking
lot.
5. It appears private sanitary sewer easements are needed for several laterals as they cross property
lines.
6. The plan is missing a few drainage easements. Drainage easements are necessary for pipes
Engineering Review Comments
Page 2 of 3
carrying water from public ROW or adjacent parcels.
7. Please show all easements on the Landscape plans. At least one of the new drainage easements
will require the relocation of a proposed tree.
8. All necessary easements must be recorded before the site plan can be approved.
9. Please show sight distance lines for all entrances onto the public ROW.
10. Please provide a VDOT designation on the plan for each new entrance.
11. The minimum radius on an entrance to VDOT ROW is 12.5ft (VDOT's requirement may be
larger).
12. Please provide a traffic generation summary for the site onto the existing public road.
13. Curbing is required in more areas than where it is currently shown on the plan. In all locations
where improvements are made, curbing is required. Curbing requirements can only be waived by
Current Development Engineering when pavement drains to Stormwater Management Facilities.
14. Please provide a VDOT designation for the endsections in the profiles.
15. Please specify the grate type for each DI -1.
16. Concrete inlet shaping IS -1 is required on all structures with a 4ft or greater drop, including drops
from surface level.
17. In the profiles, please label and dimension the outlet protection from each pipe system.
18. The profiles for 3 culverts are missing from the plan. Spot elevations for culvert inverts should
also be provided in plan view.
19. Calculations for the culverts are required. Culverts must not have a head greater than 1.5 x
Diameter and the water level must be 18" below the shoulder elevation.
20. The inlet drainage area map is missing watersheds for several existing and proposed structures and
channels. The text on the plan is also difficult to read.
21. For each watershed in the inlet drainage area map, please provide the average C -value and time of
concentration. [DM]
C. Stormwater Management Plan Review (WPO- 2008 - 00091)
1. SWM facility 3 should be moved outside of the area reserved for interparcel connection.
2. A copy of the Lickinghole Basin pro -rata share for the site will be calculated by County
Engineering once the plans are ready for approval.
3. For each watershed in the SWM facility drainage area maps (both pre and post), please provide the
average hydrologic coefficient.
4. During the review of the plan I've found the following discrepancies that should be corrected on
the next submittal:
A. The embankment details for Basin 1 and 2 specify widths of 8ft, but both embankments
are shown wider on the plan. All embankments are satisfactory as drawn in plan view.
B. The invert of the culvert in Basin 3 is mislabeled in the section detail.
C. The grading for Basin 2 does not appear to show an emergency spillway at elevation 633
as suggested in the embankment detail. It does not appear that a spillway is necessary for
this facility and the grading can remain as shown
D. A 664 contour line is labeled as 666 in Basin 3.
5. Please provide an overall detention compliance table for each facility.
6. The latest (July 2005) 24 hour rainfall totals for the 2, 10, and 100 years storms are 3.7in., 5.6in,
and 9.1in., respectively. Please update calculations.
7. Please raise the elevation of the incoming 15" pipes in storm lines E and D to the highest invert as
possible to limit the backing water into the smaller pipe.
8. The SWM portion of the bond will be computed when the plans are ready for approval.
9. Additional requirements may be necessary depending on the determinations of the Planning and
Zoning Departments regarding the biofilters shown on the approved rezoning plan. Please see
comment A. LA.
Engineering Review Comments
Page 3 of 3
D. Erosion and Sediment Control Plan Review (WPO- 2008 - 00091)
1. Engineering review is concerned about the lack of adequate channels for all of the concentrated
discharge from pipes and channels. Please provide channel adequacy calculations or provide level
spreaders at each outfall. Each level spreader should be included inside either a SWM or drainage
easement depending on where the water is coming from.
2. A sediment trap appears to be necessary at the end of the reconstructed channel (west of the two
15" cedar trees) between buildings 8 and 9. A fill diversion should be extended to the west to
direct all runoff for the area around building 8 to this trap.
3. The elevation of the dam in sediment trap 1 should be lft above the crest elevation of the weir.
Engineering review recommends that a culvert inlet sediment trap be used in this location so
minimal earthwork is required when converting from ESC to SWM in the final stage of
construction. Please see VESCH standard 3.08 for CIP -ST requirements.
4. Not all land disturbances have been included in the limits of construction. For instance, the
waterline across Meadows Drive is not shown within the limits of construction.
5. Please place a construction entrance near building 20. The gravel base of the parking lot can be
used as a construction entrance during the earthwork operations as long as it meets the minimum
dimensions for a CE.
6. The existing soil boundaries on the plan are confusing. Please clarify or provide a smaller map
detail on another sheet.
7. Please provide a staging and parking area on the plan. The parking spaces and areas adjacent to
each building could be used as parking and staging areas.
8. Four hundred feet of additional silt fence is needed on sheet SS -1 for the construction of the
sanitary sewer line.
9. Silt fence is needed downhill of the private sanitary sewer line on sheet ESC -3.
10. The ESC portion of the bond will be computed when the plans are ready for approval.
File: E1_fmj esc swm _PBC_WP0200800091_SDP200800134 Meadows Expansion.doc