HomeMy WebLinkAboutWPO201700005 Other 2017-03-20 (2)])AM
AND ASSOCIATES INC
REFLECTING TOMORROW
March 14, 2017
Engineering Department
County of Albemarle
401 McIntire Road
Charlottesville, VA 22902
RE: Response to Comments
Timberland Park Apartments - Final
Balzer Project No: 34160034
County Project No: WP0201700005
This letter serves as our written responses to the attached February 17, 2017 Engineering comments
on the subject project:
A. Stormwater Pollution Prevention Plan (SWPPP)
1. Please update any E&S or SWM sheets if changes are made with the next submission. E&S
and SWM sheets updated with this submittal.
2. Ensure that the offsite disposal area is added to the SWPPP. Offsite disposal area was added
to the SWPPP.
B. Pollution Prevention Plan (PPP)
1. PPP appears satisfactory at this time. Noted.
C. SWM Plan
1. Detention pipe is located offsite. Please show the agreement that allows this or move the pipe
on the property. Also, if these pipes convey offsite water, they will need to be in an easement.
Detention pipes are located onsite. A temporary grading easement has been provided to
ensure flow from detention outlet to existing culvert under Old Lynchburg Road.
PLANNERS ' ARCHITECTS ' ENGINEERS ' SURVEYORS
ROANOKE ' RICHMOND ' NEW RIVER VALLEY' STAUNTON ' HARRISONBURG
1561 Commerce Road, Suite 401 ' Verona, Virginia 24482 ' (540) 248-3220 • FAX (540) 248-3221
Response to Comments
Timberland Park Apartments
Page 2 of 3
2. Grading occurs offsite in the NE corner. Please show the agreement or temporary easement
that allows this proposed grading. Approval by VDOT has been received for the grading off
the NE corner of the property in VDOT R-O-W.
3. Level 2 bioretention requires 2 forms of pre-treatment. Please illustrate the 2 forms being
used. Two forms of pre-treatment have been provided for both Level-2 bioretentions
(sediment forebay & grass filter strip).
4. Provide infiltration test results or underdrain in BMP #2. Both bioretentions are now being
underdrained.
5. Please provide maintenance requirements for detention pipe on the plan to include annual
inspections, cleanings and necessary repairs. Maintenance requirements for Detention pipes
have been added, Sheet C 10.
6. The actual Q Dev on PDF page 51 was whited out. Please correct so the number is shown.
Actual Q Dev shown on page 78 of the Stormwater Management Report (dated 03-14-2017).
The 1-YR Energy Balance calculation has also been thoroughly explained.
7. Provide summary/narrative on plan sheet that describes compliance with water quality and
quantity requirement (show pre vs post quantity and phosphorus removal required vs achieved
quality). Supporting calculations can remain in the provided SWM report. A summary has
been provided that details pre vs. post compliance for water quantity and quality, Sheet C7.
8. Provide an easement around the BMP facilities that includes access for maintenance. An
access easement has been provided for all BMP facilities (bioretentions and detention pipes),
Sheet C4.
9. Please ensure that water drains away from the buildings. Provide spot elevations in the
graded ditches. Show that these graded ditches will not erode over time. To ensure water
drains away from buildings, spot grades have been added to the graded ditches. No mulch
lines are proposed in ditch to help ensure longevity of integrity.
10. Provide detail for PG-4 flume and show the proposed flow/velocity vs. its capacity. PG-5
detail has been added to plans (Sheet C17), as well as a SCC calc showing 2-YR velocity and
10-YR depth for the paved ditch (Sheet C7).
11. Show equations used for inlet calculations or use standard VDOT Appendix I" T D-204
Stormwater Inlet Computations. Inlet computations (VDOT Appendix 913-1 LD-204) have
been added to Sheet C 12.
12. Ensure that drainage in the southern corner of the site does not runoff into neighboring
properties. It should be directed to the point of analysis 2 on site. A diversion has been added
to ensure drainage in the southern corner of the site does not runoff into neighboring
properties, Sheet C7.
13. A Stormwater Management (SWM) Maintenance Agreement and a SWM Easement Plat with
a SWM Deed of Dedication will be needed before the VSMP plan can be approved. Please
contact Ana Kilmer to begin the process of completing the Maintenance Agreement. The
application for an easement plat can be found here:
http://www. albemarle. org/upload/images/forms_center/departments/Community_Developme
nt/forms/applications/Easement_ Plat_&_Checklist.pdf. The fee for the easement plat will be
the one shown for the easement plat required with a site plan. We recommend you begin this
n-i-c-c ac, soon as nn-0-11e. Noted.
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1561 Commerce Road, Suite 401 ' Verona, Virginia 24482 ' (540) 248-3220 • FAX (540) 248-3221
Response to Comments
Timberland Park Apartments
Page 3 of 3
D. Erosion Control Plan
1. Please provide a separate existing conditions sheet and ESC Phase 1 sheet. Insert the ESC
Phase I sheet with the other ESC sheets of the plan set. A separate ESC Phase 1 sheet has
been added, Sheet C6.
2. Please remove all "field observed steep slopes". Only the steep slopes from the County GIS
should be shown. All "field observed steep slopes" have been removed.
3. Show a wash rack on plans with the construction entrance. Ensure that water from wash rack
is directed to the sediment trap. A wash rack has been added and directed to Sediment Trap
#1, Sheet C6.
4. A paved construction entrance is required for this site. Gravel will not be allowed. Please
note this on the plans. Paved Construction Entrance noted on the plans, Sheet C6.
5. Show dust control and temporary seeding on ESC Phase 1. It is currently only shown on
Phase 2. Dust control and temporary seeding shown on ESC Phase 1, Sheet C6.
6. Show the stockpile, concrete washout, staging area, etc. on Phase 1 as well as Phase 2.
Staging area, stockpile, concrete washout, etc. shown on ESC Phase 1.
7. Please explain why RWD diversion was used in the NW corner of the site. There does not
appear to be a road or travel way. DD on Phase 1, RWD on Phase 2.
8. It appears the required outlet protection on structure 13 will be offsite. Please obtain/provide
a temporary access easement/agreement. OP for STR #13 & STR #39 no longer offsite.
9. Ensure that grading/construction of retaining wall in the NW corner of the site does not
encroach on the steep slopes. Grading/construction of retaining wall in NW corner of site does
not encroach on the steep slopes. This part of the wall is not tall.
10. Please label and darken the contours for the proposed sediment traps. The contours of the
sediment trap have been labeled and darkened, Sheet C6.
11. Show OP symbol at structure 13 Out. OP symbol for STR #13 & STR #39 shown.
12. The landscape plan shows proposed trees outside of the limits of disturbance and in the steep
slopes in the NW corner. Please remove. Proposed tree locations revised.
Sincerely,
BALZER AND ASSOCIATES, INC.
117
D. Kent O'Donohue Jr., PLA
Landscape Architect
Project Manager
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1561 Commerce Road, Suite 401 ' Verona, Virginia 24482 ' (540) 248-3220 • FAX (540) 248-3221