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HomeMy WebLinkAboutWPO201400010 Correspondence 2014-02-18 ETTER OF TRANSMITT . (RECEIVED .44%#411ffr MAR 2 , 2014 Tc DESIGN FACILITIES D V, 500 FIRM Engineering News Record A. Morton Thomas and Associates, Inc_ 3/24/14 110-886.004 Consulting Engineers DATE AMT PROJECT NO. Community Development Cale Elementary School TO AMT PROJECT NAME County of Albemarle Don Rissmeyer, P.E. COMPANY FROM 401 McIntire Road Charlottesville, VA 22902-4596 Parking Lot Improvements ADDRESS RE 434-296-5832 Blake Abplanalp (copies are noted below) PHONE FAX COPIES TO Sent Via: MAIL L PICK-UP DC MESSENGER 1 OVERNIGHT E-MAIL FAX Comments: Here is our second submittal for the design of a new parking lot at Cale Elementary School for Albemarle County. We are distributing the following copies with this re-submittal package. Minor Site Plan Amendment(To: Ellie Ray) 2 sets of site plans 2 sets of E&S plans - 1 copy of the SDP comment response letter ARB Review(To: Margaret Maliszewski) - 1 set of the site plan amendment - 1 sets of E&S plans - 1 copy of the ARB comment response letter WPO Application (To: Frank Pohl& Blake Abplanalp) 2 sets of site plans 2 sets of E&S plans - 2 sets of drainage calculation reports 2 copies of the comment response letters (SDP, ARB and WPO) 100 Gateway Center Parkway, Suite 200 Richmond, Virginia 23235 Phone: (804)276-6231 Fax: (804)276-6233 E-mail: drissmeyer @amtengineering.com ift41117.1-'" rroP DESIGN 500 FIRM° A.Morton Thomas and Associates,Inc. Engineering News Record Consulting Engineers March 21, 2014 AMT Project No. 110-886.004 Re: WPO 2014-00010-Cale Elementary School -Parking Lot Improvements Minor Site Plan Amendment Department of Community Development Comments Please find below the comments dated March 7th from the review of the referenced Cale Elementary School project repeated below in italics type with our respective responses in bold type. 9. The approved plan must be included in the plan set, with the specific areas of amendment clearly outlined by bubbling or circling affected areas. The approved plan must not otherwise be altered. The location of this proposed parking lot is depicted on the Tree Replacement Plan which utilizes a previously approved site landscape plan from SDP #05-00113 as a base map. The cover sheet also notes SDP-2006-01 as a previously approved plan reference,taken from our correspondence with Ellie Ray. [18-32.6.6, 14-302]Include an existing conditions plan in the plan set. An existing conditions plan has been added too the plan set. ` 3. [18-32.6.6, 14-302]Add description of datum reference to Note 9, General Notes. The Cover Sheet has been revised to reflect the datum reference in the general notes. 4. [18-32.6.6, 14-302]Indicate date of field survey in Note 10, General Notes. The Cover Sheet has been revised to reflect the date of field survey in the general notes. [32.5.2(a)]Show present use on abutting parcel to the south. The adjacent parcel information has been revised to reflect the present use of the parcels. V/6. [32.5.2(a)]Show setback line for parcel to the south. 15' and 20' setback lines have been added to the dimensional site plan for the nearest property line to the south. l ' [32.5.2(a)]Add overlay districts to the General Notes(Airport Impact Area and Entrance Corridor). The Cover Sheet has been revised to add overlay districts to the general note on the zoning designation. [32.5.2(a)]Include Comp Plan Use, Primary, Secondary and Land Use information in General Notes. The Cover Sheet has been revised to add Comp Plan Use, Primary, Secondary and Land Use information to the general notes. PHONE: 804-276-6231 FAX:804-276-6233 E-MAIL: drissmeyer@amtengineering.com 100 Gateway Centre Parkway, Suite 200 Richmond, Virginia 23235 ..• March 21, 2014 Page 2 ✓9 [32.5.3(d)] Show area of critical slopes as obtain from the County GIS website. If critical slopes are impacted, a critical slope impact application is required. An area of managed critical slope has been added to the Existing Conditions Plan. To adequately drain the parking lot and provide stormwater management it will be necessary to impact a portion of critical slope with an additional pipe outfall. Impacts will be minimized by including a rip-rap flume to mitigate possible erosion. -- /t id F 7�--G.m-t'p / t t/E'er eC t}--e -• d :j 4 �r „ , t: . z- `;, ,.. ',+'"'is i"_1:--- r -e-A V c / . [32.5.2(f)]Indicate the watershed in Note 13, General Notes (Moore's Creek watershed). ) ° The Cover Sheet has been revised to indicate the watershed designation in the general notes. 11. [4.12.16.c.6]Parking spaces may be reduced to 16-ft deep where a 2-ft grassed overhang is provided. The Site Dimensional Plan has been revised to reduce the parking space along the southern perimeter to a depth to 16-foot with a ' grass overhang. , t q s t fd 12. [Design Manual, Section 3.F1 The adequate channel analysis provided does not address / all requirements of the Design Standards Manual. / 14 4(1- A more complete adequate channel analysis has been included in the drainage , vii y report for the grassed swale at our project's point of discharge and at the existing stormwater management basin in the corner of the site. As shown in the .L-t4„,t6 p' ' drainage calculations the discharge end of the existing stormwater basin is where * ' 4' this projects disturbed areas are less than 1% of the entire watershed meaning r 1,1-,, j X`� there are no anticipated impacts further downstream to evaluate. \tip\ c U� 13. [Design Manual, Section 5]It appears that only detention (water quantity) is being \ e \' provided. Water quality shall also be addressed for all additional impervious areas. 1. Please provide pollutant loading and removal calculations. Facility may need to be revised to provide treatment. '' The Design Report has been revised to include water quality calculations for pollutant loading and removals. Bioretention basins have been added to the design. ✓ 14. [Design Manual, Section 8]Proposed slopes steeper than 3:1 shall have low maintenance (not grass) ground cover specified on the plans. Proposed slopes shall not exceed 2:1. No slopes exceed 3:1. V6 Please indicate slopes within detention facilities on the plan. The Grading Plan has been revised to reflect side slopes of the detention facilities. 16. rovide a stage-storage table with water quality volume for each facility on the drawings. he Grading Plan has been revised to reflect a stage-storage table and the water _ quality volumes for each facility on the drawing. ..,rr f✓ E' , ;4 ” _ �/try `- 17. Provide a summary table indicating pre/post flow rates and velocities for the design \,_F storm events for each facility on the drawings. The Grading Plan has been revised to reflect a summary table of the pre/post flow rates and velocities for the design storm events. A. MORTON THOMAS and Associates, Inc. woo woof March 21, 2014 Page 3 Indicate Curve Number and Time of Concentration on drainage maps. The Drainage Maps have been revised to reflect the curve number and time of concentration for each drainage area. E&S plan shall be a separate set of plans. Please submit separate plan sets for the site plan application and the E&S Control application. A separate Erosion and Sediment Control Plan set has been developed. 1710. Provide an existing conditions plan as part of the E&S Plan. The Existing Conditions Plan is part of the Minor Site Plan Amendment and the Erosion and Sediment Control Plan set. 21./Provide cross sections of SWM facilities, to include: dimensions, storm staging for 2- and ---, 10-yr events, treatment stage elevation, width of embankment, side slopes, freeboard, etc. A Stormwater Management Plan has been added to the plan set depicting dimensions, peak stage for the 2-and 10-yr events, treatment stage (water quality) elevations, width of embankment, side slopes, and freeboard for each facility. yel.. For embankments over 3-ft high, the top of back should have a minimum width of 8-ft. This applies to the detention facilities. Bioretention Basin's A and B have embankment heights of less than 3-feet. L 2 Inverts from the ponds appears to be below the elevation shown (i.e. pipe inv. elevation =576.82 and contour= 578.00). Show grading at headwalls/riprap. The Grading Plan has been revised to reflect the addition of water quality features to the detention basins, and inverts have been updated. \Confirm benchmark elevation (384.61?). The topographical error of the benchmark elevation has been corrected. l45. Submit letter of approval from the County ARB once received. The approval letter from the County ARB will be provided upon receipt. , 6. It appears that the sediment trap weir has an elevation of less than 580 when looking at the contours. However, the sizing chart states the top elevation of weir is 581. The Erosion and Sediment Control Plan has been revised to reflect revisions to the sediment trap information table. \7. The overflow weir from the sediment trap should include outlet protection. The Erosion and Sediment Control Plan has been revised to reflect the addition of outlet protection to the overflow weir. J8. Consider moving the locating of the silt trap to where future pond will be. Once the hole is excavated it can be used for both the silt trap and the future SWM facility. This is just a suggestion. The Erosion and Sediment Control Plan has been revised to reflect the relocation of the sediment trap to the location of the permanent SWM facility. A. MORTON THOMAS and Associates, Inc. March 21, 2014 Page 4 IX:Identify what "RR"means on the E&S Control Plan. The Erosion and Sediment Control Plan has been revised to reflect the removal of "RR" designation. It was previous used to designate rip-rap. . Change direction of Diversion Dike on E&S Control Plan. The Erosion and Sediment Control Plan has been revised to reflect the correct direction of the diversion dike. vd7 Submit ARB approval letter showing the landscaping plan meets County requirements. See comment response#25. Please let us know if you have any questions regarding our responses to these comments or if you need additional information. Thanks for your assistance with this project. Sincerely, Don Rissmeyer, PE Associate A. MORTON THOMAS and Associates, Inc.