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Home My WebLink AboutWPO201300028 Review Comments 2013-04-16 . r 5 ,,,e-00 c�`,e ;_ Dominion 172 South Pantops Drive y;a • Engineering Charlottesville, VA 22911 0.4 434.979.8121 (p) � 434.979.1681 (f) e SS DominionEng.com May 16, 2013 Ms. Michelle Roberge Albemarle County Department of Community Development 401 McIntire Road Charlottesville, Virginia 22902 RE: Castle Hill Cider- Comment-Response Letter— WPO 2013-00028 Dear Michelle, Enclosed please find two (2) sets of revised WPO plans and two (2) sets of Erosion and Sediment Control Narrative and Simple4 calculations. Please note that we have revised the plans to address your comments dated May 1, 2013 in accordance with the following: ENGINEERING COMMENTS A. SWM Plan (WPO201300028) 1) The road elevation abutting the detention pond is below the 10 year water elevation. Also, it does not appear that a detention pond is necessary at the proposed location. There are (2) -24" existing RCP pipes from Turkey Sag Rd draining south to a low spot. A proposed 15" culvert drains to the same low spot, east of proposed road, before it enters existing culvert EX-1. One solution is for the entrance to be flattened to a max of 4.5%for gravel to stay in tact and establish a vegetative swale for water quality west of proposed road. RESPONSE: The stormwater management facility has been removed. 2) Please provide the removal rate calcs. RESPONSE: A simple-4 worksheet has been included with this submission and is attached to this comment letter. 3) Please address MS-19. RESPONSE: We have expanded our drainage study and added a surveyed downstream cross section. The receiving ditch is adequate to convey the design flow at non-erosive velocities. As discussed at our post submission meeting on May 9,we have added a note for the portion of outfall that is characterized by sheet flow below the ditch. This note allows the County to pull the bond to complete ditch improvements if there are signs of erosion following construction. B. Erosion Control Plan (WPO201300028) 1)A VDOT permit is required for entrance improvements. RESPONSE: VDOT has approved the plan and the owner is currently working with VDOT to obtain the entrance permit. Page 1 of 3 ev s e is r��y�' Dominion 172 South Pantops Drive °'y;a ► Engineering Charlottesville, VA 22911 69 434.979.8121 (p) �� I ,. 434.979.1681 (f) 9�ej'S DominionEng.com 2) The location is not clear for the proposed road widening shown in inset on sheet S2. Please provide a dimension from the intersection or stationing to locate improvements. RESPONSE: A dimension has been added showing the distance to the turnaround intersection. 3) Please provide pavement sections for the following: a. The proposed entrance b. The road to be widened from comment 2 c. The new turnaround RESPONSE: Typical pavement sections have been provided for each location. 4) Please provide a separate sheet with existing conditions and include items to be removed, such as fence. RESPONSE: As discussed at our May 9 meeting, we have clarified the items to be removed by adding more effective labeling and linetypes, and therefore, a separate existing conditions sheet is not required. 5) In conjunction with comment 1 from section A, SWM Plan, the diversion dike shall be extended north and relocated outside limits of grading. Please show a high point to divert clean water north and south. RESPONSE: The clear water diversion has been pushed to the high side of the limits of grading. A high point has also been added. 6) Please place one sediment trap west of proposed road. Please provide calcs for sediment trap. RESPONSE: We have added a culvert inlet protection with excavated sediment trap as discussed. The detail and calculations have been added to the plans. 7) Please place a culvert inlet protection lined with rip-rap in horseshoe shape. Please provide detail. See 3.08 in VESCH. RESPONSE: Please see response to comment#6 above. 8) Please place a RWD approximately 10' before intersection to divert water from proposed road to sediment trap. A slope drain can be placed behind this RWD to divert clean water from diversion dike to culvert EX-1. RESPONSE: A RWD has been added as requested. 9)The construction entrance on plan is not 70' long. Please show on plan. RESPONSE: The construction entrance has been updated to 70' long. 10) Please provide dust control on plan. RESPONSE: Dust control symbols have been added. 11) Please provide the E&S narrative on plan. Page 2 of 3 �s �e ors te Dominion 172 South Pantops Drive y ► Engineering Charlottesville, VA 22911 ,,°1' I ; 434.979.8121 (p) *,P 434.979.1681 (f) Hers s DominionEng.com RESPONSE: An E+S narrative has been provided as a separate attachment. We trust the above adequately addresses your comments. Please let me know if you have any questions or require additional information. Very truly yours, Aitickxat �►�t�er5 Michael Myers, P.E., C.F.M. Attachments Cc: John Rhett Page 3 of 3 Short Version BMP Computations For Worksheets 2 -6 Albemarle County Water Protection Ordinance: Modified Simple Method Plan: Castle Hill Cider Water Resources Area: Development Area Preparer: Dominion Engineering Date: 03/29/2013 Project Drainage Area Designation DA SWM-1 L storm pollutant export in pounds, L=[P(Pj)Rv/12][C(A)2.72] Rv mean runoff coefficient, Rv=0.05+0.009(1) Pj small storm correction factor,0.9 1 percent imperviousness P annual precipitation,43"in Albemarle A project area in acres in subject drainage area A= ..1-29,92 C pollutant concentration,mg/I or ppm target phosphorus f factor applied to RR ✓ required treatment volume in cy,0.5"over imperv.area= A(I)43560(0.5/12)/27 RR required removal, L(post)-f x L(pre) %RR removal efficiency, RR100/L(post) Impervious Cover Computation(values in feet&square feet) Item pre-development Area post-development Area Roads&Parking Length Width subtotal Length Width subtotal 0 0 35719 0 0 35719 0 0 0 0 0 1307 0 0 0 0 0 35719 0 37026 Driveways Length Width no. subtotal Length Width no. subtotal and walks 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 - 1 2 3 4 1 2 3 4 0 0 0 Gravel areas Area Area 4792 x 0.70= 3354.4 9583 x 0.70= 6708.1 ; Structures Area no. subtotal Area no. subtotal 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Actively-grazed pasture& Area Area yards and cultivated turf 1123412 x 0.08= 89873 1117314 x 0.08= 89385.12 Active crop land Area Area x0.25= 0 x0.25= 0 Other Impervious Areas 0 0 Impervious Cover 10% 11% l(pre) l(post) Rv(post) V 0.15 ' =.,205.4 New Development(For Development Areas,existing impervious cover<=20%) C f I(pre)* Rv(pre) L(pre) L(post) RR %RR Area Type '070 - 1 00 20% 0.23 40.83 25.76 -15.07 - ,,--A''..-.690/1; Development Area 035 ' 100 fo 0.14 12.62 12.88 0.26 2:',,-,-.° - Drinking Water Watersheds 040 '.`.-1.00 = 1% 0.14 14.42 14.72 0.30rt. 2%' Other Rural Land *min.values .._ Redevelopment(For Development Areas,existing impervious cover>20%) C f I(pre)* Rv(pre) L(pre) L(post) RR %RR Area Type ' -0 70 090 *u 20% 0.23 40.83 25.76 -10.99 -43% Development Area '0.'. 5 f``; 85 - 0% 0.14 12.62 12.88 2.16 17% Drinking Water Watersheds 040 . - 0.85 ,.,.� 1% 0.14 14.42 14.72 - 2.47 '':,7,,,,,-„,,,;‘,-,- . "17%, Other Rural Land Interim Manual, Page 70 rev. 16 Feb 1998 GEB COUNTY OF ALBEMARLE Department of Community Development 401 McIntire Road, Room 227 Charlottesville, Virginia 22902-4596 Phone (434) 296-5832 Fax (434) 972-4126 Project: Castle Hill Cider Plan preparer: Dominion Engineering [979-8121] Owner or rep.: Raymond Humiston LLC Plan received date: 9 Apr 2013 Plan received date for Engineering review: 16 Apr 2013 Date of comments: 1 May 2013 Reviewer: Michelle Roberge I have completed the engineering review for WPO2013-28. Please see below for the following comments. A. SWM Plan (WPO201300028) 1) The road elevation abutting the detention pond is below the 10 year water elevation. Also, it does not appear that a detention pond is necessary at the proposed location. There are (2) - 24” existing RCP pipes from Turkey Sag Rd draining south to a low spot. A proposed 15” culvert drains to the same low spot, east of proposed road, before it enters existing culvert EX-1. One solution is for the entrance to be flattened to a max of 4.5% for gravel to stay in tact and establish a vegetative swale for water quality west of proposed road. 2) Please provide the removal rate calcs. 3) Please address MS-19. B. Erosion Control Plan (WPO201300028) 1) A VDOT permit is required for entrance improvements. 2) The location is not clear for the proposed road widening shown in inset on sheet S2. Please provide a dimension from the intersection or stationing to locate improvements. 3) Please provide pavement sections for the following: a. The proposed entrance b. The road to be widened from comment 2 c. The new turnaround 4) Please provide a separate sheet with existing conditions and include items to be removed, such as fence. 5) In conjunction with comment 1 from section A, SWM Plan, the diversion dike shall be extended north and relocated outside limits of grading. Please show a high point to divert clean water north and south. 6) Please place one sediment trap west of proposed road. Please provide calcs for sediment trap. 7) Please place a culvert inlet protection lined with rip-rap in horseshoe shape. Please provide detail. See 3.08 in VESCH. 8) Please place a RWD approximately 10’ before intersection to divert water from proposed road to sediment trap. A slope drain can be placed behind this RWD to divert clean water from diversion dike to culvert EX-1. 9) The construction entrance on plan is not 70’ long. Please show on plan. Engineering Review Comments Page 2 of 2 10) Please provide dust control on plan. 11) Please provide the E&S narrative on plan. Sincerely, Michelle Roberge File: E1_rp,esc,swm,fsp_GEB_template.doc