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HomeMy WebLinkAboutWPO201400068 Review Comments WPO VSMP 2014-12-02 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: Farmington Country Club Southside Improvements -WPO Plan preparer: WW Associates Owner or rep.: Farmington Country Club Plan received date: 28 Nov 2014 Date of comments: 2 Dec 2014 Reviewer: Michelle Roberge County Code section 17-410 and Virginia Code §62.1-44.15:34 requires the VSMP authority to act on any VSMP permit by issuing a project approval or denial. The comments below have been addressed; however, the applicant stated that a revised plan will be submitted. That new plan will be reviewed to ensure it is in general accord with the comments below and the WPO ordinance. No additional fee is required for resubmittal. The VSMP application content requirements can be found in County Code section 17-401. A. WPO (WPO2014000068) 1) [Comment] Show soil map of site. [Revision 1] Comment addressed. The soils are shown on sheet C -12. 2) [Comment] The drainage area A table on sheet C-13 shows a BMP practice to a rain garden #2. The plan does not show a rain garden. Please clarify if you are proposing a rain garden. [Revision 1] Comment addressed. There is no rain garden proposed. This has been removed from the table. 3) [Comment] The sloped area south of the proposed parking lot all drain to the biofilter, but only .5 acres is shown going to the bioretention practice. It appears more than .5 acres will drain to biofilter. Please revise. [Revision 1] Comment addressed. Applicant confirmed the areas going to the biofilter. The existing improvements north of parking lot will drain into an existing stormsewer system that will eventually bypass the biofilter. 4) [Comment] Add this note on C-12 for biofilter mix. “Tested for acceptable phosphorus index between 10 and 30 or between 7 and 23 mg/kg of P in soil media.” [Revision 1] Comment addressed. 5) [Comment] Submit perc rate for biofilter area. (One per 1,000 sq ft of filter surface). Also, verify that the bottom of #57 aggregate is 2’ above seasonably high water table. Engineering Review Comments Page 2 of 5 [Revision 1] Comment not addressed. The bottom of the biofilter is 601 .16 and the geotech report states that groundwater is present at test site HA-3. The geotech submitted an email stating that the water is perched at HA-3. The response doesn’t clear up my concern about groundwater due to the following reasons: i) The tests were not advanced below 601 (the bottom of the biofilter). If it is perched how far below is the groundwater table? We need to clarify that there is no groundwater at 2’ below the biofilter. ii) The response from the geotech states the 6 nearby IT locations were dry as well. Which 6 tests is he referencing? This is useful if tests are within the biofilter area. Here are my recommendations. A) You can resubmit the report addressing the above concerns. We just need the geotech to sign and seal the doc. The email below will not suffice. B) Or revising layout to raise bottom of basin elevation to 603. For example, you can move the biofilter just south of the parking lot to a higher elevation. If A doesn’t work, then unfortunately, we will have to explore option B. Revision 2] Comment addressed. ECS Mid-Atlantic, LLC advanced three additional boring samples below the bottom of proposed biofilter. See certified letter from ECS. 6) [Comment] Label underdrain with Schedule 40 PVC with cleanouts. Show 12” depth for #57 aggregate. [Revision 1] Comment addressed. 7) [Comment] The geometry of basin does not meet spec of bioretention design criteria. Short circuiting should be prevented. Please revise. [Revision 1] Comment addressed. 8) [Comment] Show the 2’ gravel diaphragm level spreader at pretreatment area. On profile view, show the lip on level spreader. [Revision 1] Comment addressed. 9) [Comment] I recommend moving the curb cut location away from the corner of parking lot and shifting layout of gravel spreader to enter far east side of biofilter. [Revision 1] Comment addressed. 10) [Comment] Two rip rap strips are shown on plan, but only one profile view is shown. Please show both since one is from sidewalk and the other from the culvert under the golf cart path. My concern is that #57 stones will wash away at steeper slopes. The detail shown is for sheet flows off pavement, then into a pretreatment area that is flat. Please clarify design since the detail has been modified. [Revision 1] Comment partially addressed. The weir is 5’ wide on plan view. Please revise to provide room for weir as it appears to conflict with the gravel level spreader location. Engineering Review Comments Page 3 of 5 [Revision 2] Comment addressed. 11) [Comment] The water quantity analysis for channel protection should show the actual drainage area to the point of analysis, such as drainage area A, B, C and existing areas. The CN should be different to drainage area D. The spreadsheet shows how much phosphorus to remove, but channel analysis cannot be determined by the separate disturbed drainage areas alone since the CN is not correct. [Revision 1] Channel protection is addressed. At our engineering meeting, we directed applicant to show adequate channels further downstream since the energy balance equation at point of discharge was not met. The entire site is owned by Farmington Country Club and applicant was able to look 450’ downstream to show adequate channel within their sit e. 12) [Comment] Please clarify the total drainage area to pond. It appears to be larger than what is shown. [Revision 1] Comment addressed. 13) [Comment] Clarify the surface elevation of the bioretention area. The profile shows 607, but the plan view shows 606. [Revision 1] Comment addressed. The surface elevation is 606. 14) [Comment] Relabel bioretention facility #2 under the Bioretention Facility sizing calculations. It should be bioretention facility #1. [Revision 1] Comment addressed. 15) [Comment] Submit a Pollution Prevention Plan and a Stormwater Pollution Prevention Plan. [Revision 1] Comment addressed. New Comment 16) [Comment] The disturbed acreage on sheet C10 should match the registration statement in the SWPP. [Revision 2] Comment partially addressed. It should also match the SWPP. The SWPP does not need to be resubmitted, but the actual SWPP on construction site should match registration statement. 17) [Comment] The forebay area is in addition to the bioretention area required. It is sized to at least 15% of the total Treatment Volume. Please revise. [Revision 2] Comment addressed. The forebay was resized. 18) [Comment] For future reference, please use the Albemarle County SWPP template. For example, you can use/create the tables from section 6 B), C), D) E) F) and G). [Revision 2] Comment acknowledged. Erosion and Sediment Control Plan (ESCP) 1. [Comment] Sediment trap outlet needs to be extended to the bottom of the slope/disturbed soil area to prevent additional sediment loss during trap overflows. [Revision 1] Comment addressed. Engineering Review Comments Page 4 of 5 2. [Comment] Paved construction entrance detail needs to be on the plan. The Albemarle County Temporary Paved Construction Entrance detail can be found in the County Design Standards Manual. [Revision 1] Comment addressed. 3. [Comment] Please remove the bio-filter components from the E&SC plan sheets. Bio-filter components should be shown on the SWM pages. [Revision 1] Comment addressed. The VSMP permit application and all plans may be resubmitted for approval when all comments have been satisfactorily addressed. For re-submittals please provide 2 copies of the complete permit package with a completed application form. Engineering plan review staff are available from 2-4 PM on Thursdays, should you require a meeting to discuss this review. Process; After approval, plans will need to be bonded. The bonding process is begun by submitting a bond estimate request form and fee to the Department of Community Development. One of the plan reviewers will prepare estimates and check parcel and easement information based on the approved plans. The County’s Management Analyst will prepare bond agreement forms, which will need to be completed by the owner and submitted along with cash, certificates or sureties for the amounts specified. The agreements will need to be approved and signed by the County Attorney and County Engineer. This may take 2-4 weeks to obtain all the correct signatures and forms. Stormwater Management Facilities Maintenance agreements will also need to be completed and recorded. The County’s Management Analyst or other staff will prepare the forms and check for ownership and signature information. The completed forms will need to be submitted along with court recording fees. After bonding and agreements are complete, county staff will need to enter project information in a DEQ database for state application processing. DEQ will review the application information based on local VSMP authority approval. At this time, the DEQ portion of the application fees will need to be paid directly to the state. For fastest processing, this is done electronically with the emails provided on the application. DEQ should notify applicants with instructions on how to pay fees. When DEQ approves the application, they will issue a permit coverage letter. This should be copied to the county. After DEQ coverage is issued, via the coverage letter, the County can hold a pre-construction conference. Applicants will need to complete the request for a pre-construction conference form, and pay the remainder of the application fee. The form identifies the contractor and responsible land disturber, and the fee remaining to be paid. This will be checked by county staff, and upon approval, a pre-construction conference will be scheduled with the County inspector. At the pre-construction conference, should everything proceed satisfactorily, a joint VSMP and grading permit will be issued by the County so that work may begin. County forms can be found on the county website forms center under engineering; Engineering Review Comments Page 5 of 5 http://www.albemarle.org/deptforms.asp?department=cdengwpo Sincerely, Michelle Roberge