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HomeMy WebLinkAboutWPO200900017 Review Comments Stormwater Management Plan 2009-07-31� OF AL ,. vIRGI1`IZP COUNTY OF ALBEMARLE Department of Community Development 401 McIntire Road Charlottesville, Virginia 22902 -4596 Phone (434) 296 -5832 Fax (434) 972 -4126 Project: Wal -Mart Major Amendment Plan preparer: Dewberry & Davis, Inc. Owner or rep.: Wal -Mart Real Estate Business Plan received date: (Rev. 2) 13 July 2009 (Rev. 1) 18 May 2009 14 April 2009 Date of comments: (Rev. 2) 31 July 2009 (Rev. 1) 15 June 2009 5 May 2009 Reviewer: Phil Custer [SDP -2009- 00028, WPO- 2009 - 000171 The site plan amendment, ESC, and SWM plans for the Wal -Mart Expansion Project, received on 13 July 2009, have been reviewed. Comments for all three plans are provided in this letter. The plans can be approved after the following items have been addressed. A. Final Site Plan [SDP- 2009 - 00028] 3. The steepest slope allowed in the County is 2:1. All slopes steeper than 3:1 must have a low maintenance, non -grass groundcover. Though there are no slopes shown with proposed contours that fall into these categories, it is safe to assume that the steep slopes uphill of new walls will be disturbed. When the slopes are restored, show the proposed grading and make sure all slopes steeper than 3:1 have a low maintenance, non -grass groundcover. (Rev. 1) Comment has not been addressed. The extent of the slope disturbance has not been shown on either the grading plan or the wall detail sheet. The impacts to this slope must be determined before many of these comments can be addressed. When the slope uphill of the wall is restored it cannot be restored to existing grade because some slopes are steeper than 2:1. Please show restoration grading and propose low - maintenance groundcover on any slope steeper than 3:1. (Rev. 2) The low maintenance non -grass groundcover has been provided as required. However, the soil nail detail indicates disturbance to the property south of the development. Permission from the adjacent owner will be required with the current plan. 6. VDOT approval is required. At this time, VDOT approval has not yet been received. (Rev. 1) VDOT approval has not yet been received. (Rev. 2) VDOT approval has not yet been received. A copy of the latest plan has been sent to VDOT. 7. Engineering has reviewed the traffic study prepared by Ramsey Kemp and has some concerns with the calculations and findings. The appendix showed several movements within the study area with a level of service of E. The applicant should investigate possible improvements to bring those movements up to a level of service of at least D. The County's review of the study also questions whether a bypass reduction should be used for traffic on Hilton Heights Rd. In addition, the county believes the increase in peak hour traffic is underestimated because the ITE estimate for PM peak hour generation (370, considering bypass reduction) is well below the existing traffic counts for peak hour trips into and out of the site (607 4PM -5PM and 597 5PM -6PM). (Rev. 1) The applicant's traffic study acknowledges that after the Walmart building expansion, Albemarle County Community Development Engineering Review Comments Page 2 of 3 three turning movements affected by development (Left and Thru from EB Hilton Heights and Left from NB 29) will be operating at an E Level of Service, which is considered by engineering review to not meet Section 18- 32.7.2 (Safe and Convenient Access). Engineering review recommends that the site plan not be approved unless the applicant addresses the delay experienced for the affected movements at the surrounding intersections. (Rev. 2) Under Virginia Law, the applicant is not required to make any improvements to offset impacts. 12. With the current grading, the truck entrance will intercept most of the drainage area to the VDOT inlet and direct it into the site. Please provide a new curb inlet uphill of the entrance or modify the grading so a 4in/hr storm will continue draining to the existing DI -3 inlet. (Rev.]) On sheet 4 please provide the CG -9D callout note. The grading for the travelway also does not match the necessary vertical geometry of a CG -9D. Please provide a vertical profile detail for this entrance to verify that the all CG -9D standards are met. (Rev. 2) Comment has not been addressed. The grading in this area does not appear to match a standard CG -9D entrance. In addition to CG -9D requirements, the entrance cannot be greater than 10% in grade, measured from any point in the travelway not just the centerline. Another option could be that a new inlet is provided in the VDOT ROW immediately uphill of the entrance and modify the entrance to a CG -11 to address grading problems. 20. Please show the depth of MH -1 in the drainage profile. (Rev. 1) Comment has not been addressed. (Rev. 2) Comment has not been addressed. The depth should be shown graphically. 22. In a parking lot drainage system, all changes in direction or slope require a VDOT standard manhole or inlet. (Rev. 1) Please show the manifold risers in the drainage profile. These structures must be a VDOT Standard MH -1. (Rev. 2) The manifold risers should have VDOT standard ST -1, or equivalent, specified so the structures are accessible. B. Stormwater Management Plan [WPO- 2009 - 00017] 6. The detention pipes must be accessible at each end of the facility. The control orifice should be easily accessible. (Rev. 1) The minimum diameter outlet pipe is 15in. Also, the detention system should be arraigned in a way so that if the control orifice is clogged with debris it is easily accessible for maintenance. Right now, a clogged orifice would require someone diving into the manhole. (Rev. 2) The manifold risers should have VDOT standard ST -1, or equivalent, specified so the structures are accessible. 10. The SWM portion of the WPO bond will be calculated at the time of plan approval. (Rev. 2) The SWM portion of the WPO bond has been calculated to be $188,100. C. Erosion and Sediment Control Plan [WPO- 2009 - 00017] 1. Please provide more detail as to how the 30ft wall is to be constructed. It appears that a grading /construction easement will be needed onto the adjacent property unless pilings are used. The smaller wall between Sta. 0 +00 and 0 +90 may also require a temporary construction easement on the adjacent property. (Rev. 1) Please provide a note on both phases of the ESC plan in the area of both walls that the contractor is responsible for installing and maintaining appropriate shoring to construct the walls within the property boundaries. A temporary safety fence should also be shown at the property boundary. (Rev. 2) Please provide a note on both phases of the ESC plan in the area of both walls that the Albemarle County Community Development Engineering Review Comments Page 3 of 3 contractor is responsible for installing and maintaining appropriate shoring to construct the walls within the property boundaries. Also, the plan currently shows that disturbance to the adjacent property will occur. 11. The ESC portion of the WPO bond will be calculated at the time of plan approval. (Rev. 2) The ESC portion of the WPO bond has been calculated to be $46,600.