HomeMy WebLinkAboutWPO200800004 Review Comments Erosion Control Plan 2008-05-23ALg�,��
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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 - 00004, Martha Jefferson Phase II Grading Operation (ESC)
Plan preparer:
Mike Matthews, Matthews Dev. Company LLC fax 434.972.7769
Plan preparer:
Dan Knapp, Graef Anhalt, Scholemer & Assoc. fax 414.259.0037
Owner or rep.:
MJH Foundation [459 Locust Ave Charlottesville, VA 22902]
Date received:
(Rev. 1)15 April 2008 (plan signed 11 April 2008)
24 January 2008 (plan signed 23 January 2008)
Date of Comment:
(Rev. 1) 23 May 2008
10 March 2008
Engineer:
Phil Custer
The E &SC plan for the Phase II grading operations on the Martha Jefferson Hospital site, received on 15
April 2008, has been reviewed. The plan cannot be approved as submitted and will require the following
changes /corrections prior to final approval.
A. General review comments:
1. Please submit a payment of $2850 to the Community Development office for this ESC plan
review. This is not an amendment to the previously approved plan because the previously
approved plan did not protect the entire site area. New land is being disturbed and will require
new protection measures. Please contact me prior to the resubmittal of these plans so I can let
our intake specialists know what is coming with the plans.
(Rev. 1) Approval will be withheld until this fee is received.
2. It appears that temporary grading easements will be needed from the owners of parcel 78-
20M1 and 78 -31H. Approval of this plan will not be issued until proof that the proposed
construction operations will be allowed to take place on the neighboring properties.
(Rev. 1) The letter from Andrew Dracopoli of Worrell Land and Development Company is
not sufficient. The letter states the adjacent landowners' willingness to perform a boundary
line adjustment with the Martha Jefferson foundation referencing a previous plan that does
not show all necessary ESC disturbances. The property line used in the ESC plan also will
not be the official property at the time of the Phase II mass grading plan approval because
a plat will likely not be submitted and approved before Phase II is undertaken. I would be
happy to discuss this will Mr. Dracopoli if necessary.
3. Please include all necessary sheets that were approved on Phase I of the mass grading plan in
this set. The intention of this latest set should be to replace the existing approved plan. The
stream restoration sheets do not have to be included in this set, but the stream channel work
should be referred to in all ESC sheets.
(Rev. 1) Comment has been addressed.
4. All utilities will be reviewed and approved by the Albemarle County Service Authority.
(Rev. 1) This comment has been noted by the applicant.
5. The outlet system to Basin 1 appears to work as proposed in this plan. However, please
update this set with if the ESC amendment recently submitted ifs approved (Sheet C520 and
all other necessary information). The review of the amendment is currently pending.
(Rev. 1) Comment has been addressed.
B. Engineering review comments for ESC Narrative:
6. In the offsite section of the narrative, please state that any offsite borrow or waste area will
need to have an approved erosion and sediment control plan.
(Rev. 1) Comment has been addressed.
C. Engineering review comments for Erosion and Sediment Control plan:
7. The proposed ESC measures on the southern end of the site do not appear to adequately
protect the disturbance on the other side of the ridge. Relying on a series of diversions and
temporary slope drains to direct water to a sediment basin 400ft away from any disturbed area
is impractical for this filling operation. Engineering review recommends relocating the
sediment basin into the natural gully at the base of the large fill and extending diversion dikes
up both slopes.
(Rev. 1) The revision to the measures in this area are closer to being adequate, but will
require the following comments to be addressed before approval can be granted.
a. Please connect the diversions above traps 4 and 5 so that most runoff from above
the filling operation in Phase II -A will run to the existing basin. Please note that
this diversion should be shown with a (DV) symbol rather than (DD) and sized
based on the appropriate design discharge. Please refer to VESCH standard 3.12.
b. Sediment trap 3 should be moved farther south with diversions directing water from
the edges of the spoil area into the trap. Silt fence is not adequate in this location
because the fences run across contours and are intended to filter concentrated flow.
c. Please provide an access path on the plan to access trap 4.
d. The drainage area to trap 4 is in excess of 3 acres. Please design this facility as a
basin.
8. The construction operation next to the existing biofilter is a significant concern for engineering
review. Engineering is concerned that the proposed diversion and slope drain at the base of
this fill (just above the biofilter) may blowout and clog the stormwater facility. Please adjust
the ESC controls in this area and provide a blowup drawing.
(Rev. 1) The biofilter would be better protected from construction operations if the trap was
reconfigured so that there would not be a constructed embankment uphill of the bed area.
For instance, if the trap was moved 15ft to the south and the embankment was designed at
approximately the 492 elevation (the same as the existing embankment), then the majority
of the operation would be cut.
9. Please specify clearly in the construction sequence and on the plan when the sanitary line for
the current Martha Jefferson Hospital Foundation office is to be redirected. The hollowing out
of the basin cannot occur until the new line has been installed and the existing line removed.
Therefore, approval from the service authority for this work will be required before this mass
grading plan can be approved. Please provide a letter from ACSA when approval has been
received.
(Rev. 1) I have spoken with Tom Garrison regarding this matter. The ACSA is satisfied
with the latest alignment of the sanitary sewer line adjacent to the sediment basin. This
comment has been addressed.
10. At this time, it is difficult to review the basins and sediment traps for meeting state standards.
Please provide a blowup detail for all new sediment traps and basins of at least 30 scale with
all pertinent information labeled.
(Rev. 1) Details of all sediment traps have been provided by the applicant. A review of all
traps is as follows:
a. Please show all other necessary ESC measures (silt fence, diversion dike, etc.) in
the details.
b. The maximum slope in dry storage in sediment traps is 2:1.
c. The maximum embankment height for sediment traps is 5ft. Embankment height
is defined as the difference between the elevation of the top of embankment to the
elevation of the toe of the fill slope.
d. Embankment widths for each sediment trap should be adjusted to be in accordance
with Plate 3.13 -1.
e. The steepest grade allowed for the downstream slopes of a sediment trap
embankment is 2:1.
f. The slope north of trap 5 should be 2:1.
g. The outlet to trap 2 does not appear to be correct. The existing elevation at the end
of the rock weir appears to be close to 519. Please adjust the location of the outlet
or show the grading necessary to obtain adequate gravity flow from the wet storage
elevation.
11. Please show the limits of construction on all sheets.
(Rev. 1) Please adjust the limits of disturbance to include the construction of the sanitary
sewer line from the Martha Jefferson Offices in Phase II -A.
12. Sediment basin 2 of the phase II plan should be designated basin 3.
(Rev. 1) Comment has been addressed.
13. Please include on all erosion and sediment control sheets, all previous measures needed to
protect the disturbed areas. For instance, it is conceivable that all basins and sediment traps
(and their associated diversions) from earlier phases will be needed throughout the latest
phases of the plan. Phase II -A should show all required measures from Phase 1. Phase II -B
should show all required measures from both Phase I and Phase 11 -A, and so on.
(Rev. 1) All measures must be shown, not just basins and traps.
14. There appears to be a VDOT pipe spilling into the stream restoration area or road fill. Please
show and specify on the plan how this water is to be handled.
(Rev. 1) Comment has been addressed.
15. The Water Protection Bond has not been computed at this time.
16. Additional comments may be forthcoming on the next submittal due to required changes.
(Rev. 1) The following comments have been given due to changes from the first review of
the plan:
a. This plan proposes to disturb an existing biofilter treating runoff from the Martha
Jefferson OCC facility. The applicant must either amend this phase II plan so as
not to disturb this biofilter and its drainage area or wait until approval of the SWM
plan is given.
b. Why are limit of disturbance lines encompassing the existing entrance to the
Martha Jefferson OCC from the PJP? In addition, silt fence running across the
travelway is not acceptable.
c. The topsoil stockpiles are located on large areas of fill and may cause
complications during construction. Engineering review recommends locating the
stockpile next to the spoil area so the topsoil does not get in the way of fill
operations.
d. Please remove all references to proposed inlets and all other infrastructure not yet
approved from the construction sequence and any other location on the plan.
e. In the construction sequence, please add a step 3 in Phase II -A that requires the
installation of the diversion above the fill slopes uphill of traps 4 and 5.
f. Please note that all slopes steeper than 3:1 will require low - maintenance, non -
grassed ground cover. When specifying permanent slope stabilization in this ESC
plan, the applicant should consider this requirement.
g. Please correct the slope of the outlet barrel on detail I on sheet ESC -510.
Please contact me at (434)296 -5832 ext. 3072 should you have any questions.
File: E2_esc_PBC_08 -004 Martha Jefferson Phase H grading operations