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HomeMy WebLinkAboutSDP200500071 Correspondence Final Site Plan and Comps. 2005-08-03 Page 1 of 3 Mark Chambers From: Mark Chambers Sent: Wednesday, August 03, 2005 4:51 PM To: 'Phillip Custer' Subject: RE: A few questions regarding Waldorf School LID Design Phillip: In regard to using pervious pavers in the 8'wide zone between the handicap parking spaces. Jay Schlothauer reviewed the pertinent section of building code [ICC/ANSI A117.1-1998 American National Standard for Accessible and Usable Buildings and Facilities (particularly Sections 302 and 303)] and sent me the attached e-mail. Based on that e-mail I have the following recommendation. Find out the widths of the slots in the installed surface. If the widths are less than 1/2 inch it will be okay to install the pavers adjacent to the handicap spaces. If the widths are 1/2 inch or more please spec asphalt paving in these areas. Mark Chambers Water Resources, Reviewer/Inspector Albemarle County Department of Engineering & Public Works 401 McIntire Road, Room 211 Charlottesville, VA 22902-4596 Phone (434)296-5832 ext. 3025 Fax(434)972-4035 mchambers@albemarle.org From: Phillip Custer [mailto:pcuster@mckeecarson.com] Sent: Monday, August 01, 2005 12:15 PM To: 'Mark Chambers' Subject: RE: A few questions regarding Waldorf School LID Design Mark: Thanks for the quick response. I have just a few follow up questions. Since we plan on retaining the difference between the post and pre development runoff volumes, we assumed the underdrain wasn't necessary. It is my understanding that the underdrain is used in cases where permeability is below 0.5in/hr and the intention of the filter is simply to clean the water rather than retaining it to allow infiltration into the water table. Could you please specify any requirements for having an underdrain that I may be neglecting? Is that requirement the same for dry wells too? Lastly, I have an unrelated question. We are using concrete pavers in our parking lot similar to those in used in your county lot and filling the voids with pea gravel. Can the pavers be used in the 8ft wide zone between our two handicapped spaces or must we pave this section with asphalt? Thanks again for your time. 8/3/2005 Page 2 of 3 ikee '0•1 Philip B. Custer McKee Carson 301 East High Street Charlottesville, Virginia 22902 T: 434-979-7522 F: 434-977-1194 www.mckeecarson.com. www.fieldsport.com Original Message From: Mark Chambers [mailto:mchambers@albemarle.org] Sent: Monday, August 01, 2005 10:52 AM To: Phillip Custer Cc: Glenn Brooks Subject: RE: A few questions regarding Waldorf School LID Design Phillip: In regard to the LID design calculations I recommend following the Prince Georges County methodology. The Prince Georges Handbook does not appear to have a modified rational method. In Albemarle County we allow the use Modified Rational in traditional SWM pond/basin routings, but it may not be a good choice for LID design. The plants recommended for bio-retention facilities can generally withstand inundation (water standing around there stems)for 2 -4 days, any longer than that and the plants die, the soil becomes anaerobic and you get unwanted fungus and bacteria growth. Under normal circumstances I like to see all the standing water off the filter within 1 -2 days max, that way, when you have a wet season with frequent back to back storm events the filter will still function and you don't loose plants. Generally if you use the prescribed soil mix, install the under drain correctly, and have a maximum pond depth of 1'the filter will function. Please design the bio-retention filters to provide 1'of pond depth above the filter soil mix to the invert of the outlet structure. Let me know if I can be of any more assistance. Mark Chambers Water Resources, Reviewer/Inspector Albemarle County Department of Engineering & Public Works 401 McIntire Road, Room 211 Charlottesville, VA 22902-4596 Phone (434)296-5832 ext. 3025 Fax (434)972-4035 mchambers@albemarle.org From: Phillip Custer [mailto:pcuster@mckeecarson.com] Sent: Monday, August 01, 2005 8:53 AM To: mchambers@albemarle.org Subject: A few questions regarding Waldorf School LID Design Mark- 8/3/2005 • Page 3 of 3 )4r/ Hello. We had met earlier last week when I accompanied Eugene and Todd to your meeting to discuss the comments they got back on the Waldorf School LID project. That was Todd's last week, so another engineer and myself have taken over the design and I just wanted to run a few things by you before we submit it because I want you to only have to review this design one more time. First of all, my colleague and I are disagreeing on the method to calculate Volume needed to provide 100% retention. One method that has been used is the one outlined in Appendix A of the LID design handbook which uses Chart Series B in the LID Companion document handbook. The other method is using the modified rational method and designing retention for both the Water Quality Value and Water Quantity value because my colleague tells me that is the method primarily used in Albemarle County. Is it acceptable to design using Modified Rational Method for LID purposes? Second, is the three day drainage requirement for Bioretention filters referring to the ponded water on the surface or the complete drainage of the entire facility? Because of the large volume of water retention we are seeing on this project,we are planning on using maximum ponding depths of 1ft in our bioretention filters. Will this be accepted? I've seen maximum heights of both 6in and 1ft used in the handbook. Thanks for your time Mark. We appreciate any insight you could give us. Philip B. Custer McKee Carson 301 East High Street Charlottesville, Virginia 22902 T: 434-979-7522 F: 434-977-1194 www.mckeecarson.com WNW.fieldsport.com 8/3/2005 . 4 Page 1 of 3 Nirre '40000 Mark Chambers From: Mark Chambers Sent: Monday, August 01, 2005 4:42 PM To: 'Phillip Custer' Cc: Glenn Brooks; Jay Schlothauer Subject: RE: A few questions regarding Waldorf School LID Design Phillip: More intense planning and design considerations are required if you do not plan on using under drains in the bio- retention filter. As you pointed out under drains are needed where saturated soil permeability is lower than .52 inches per hour to a depth 3' below the bottom of the facility. You will need to have infiltration tests done as well as determine that the mean high ground water elevation is a minimum 2 feet below the bottom of the proposed facility. You will have to provide sediment control for the bio-filter areas during construction of the rest of the project so that fines cannot accumulate and alter the infiltration rate of the indigenous soils. The areas will have to be fenced off during the entire construction process so that heavy equipment and other vehicles cannot compact the soil and alter the infiltration rate. See these and other requirements for infiltration facilities in the Virginal Stormwater Management Handbook MS-3.10. Due to the above additional requirements and the fact many soils in the Piedmont will not meet the required infiltration rate most designers choose to go with the under drain system. In this case, where LID goals could be compromised by the under drains I would recommend altering the standard bio-filter cross section requiring more depth in the under drain stone. For example, you could have a under drain stone depth of 3 feet with the under drain piping system contained in the upper foot of stone. This would ensure the filter could dewater at the desired rate and allow the water stored in the lower portion the under drain to infiltrate at whatever rate the soil will provide. At this time I do not know of any objections to using the pavers adjacent to the handicap stalls. I'm waiting on confirmation from the building official and will get back to you on that. Mark Chambers Water Resources, Reviewer/Inspector Albemarle County Department of Engineering & Public Works 401 McIntire Road, Room 211 Charlottesville, VA 22902-4596 Phone (434)296-5832 ext. 3025 Fax (434)972-4035 mchambers@albemarle.org From: Phillip Custer [mailto:pcuster@mckeecarson.com] Sent: Monday, August 01, 2005 12:15 PM To: 'Mark Chambers' Subject: RE: A few questions regarding Waldorf School LID Design Mark: Thanks for the quick response. I have just a few follow up questions. Since we plan on retaining the difference between the post and pre development runoff volumes,we assumed the underdrain wasn't necessary. It is my understanding that the underdrain is used in cases where permeability is below 0.5in/hr and the intention of the filter is simply to clean the water rather than retaining it to allow infiltration into the water table. Could you please specify any requirements for having an underdrain that I may be 8/1/2005 Page 2 of 3 neglecting? Is that requirement the same for dry wells too? Lastly, I have an unrelated question. We are using concrete pavers in our parking lot similar to those in used in your county lot and filling the voids with pea gravel. Can the pavers be used in the 8ft wide zone between our two handicapped spaces or must we pave this section with asphalt? Thanks again for your time. Philip B. Custer McKee Carson 301 East High Street Charlottesville, Virginia 22902 T: 434-979-7522 F: 434-977-1194 www.mekeecarson.com www.fieldsport.com Original Message From: Mark Chambers [mailto:mchambers@albemarle.org] Sent: Monday, August 01, 2005 10:52 AM To: Phillip Custer Cc: Glenn Brooks Subject: RE: A few questions regarding Waldorf School LID Design Phillip: In regard to the LID design calculations I recommend following the Prince Georges County methodology. The Prince Georges Handbook does not appear to have a modified rational method. In Albemarle County we allow the use Modified Rational in traditional SWM pond/basin routings, but it may not be a good choice for LID design. The plants recommended for bio-retention facilities can generally withstand inundation (water standing around there stems)for 2 -4 days, any longer than that and the plants die, the soil becomes anaerobic and you get unwanted fungus and bacteria growth. Under normal circumstances I like to see all the standing water off the filter within 1 -2 days max, that way, when you have a wet season with frequent back to back storm events the filter will still function and you don't loose plants. Generally if you use the prescribed soil mix, install the under drain correctly, and have a maximum pond depth of 1'the filter will function. Please design the bio-retention filters to provide 1'of pond depth above the filter soil mix to the invert of the outlet structure. Let me know if I can be of any more assistance. Mark Chambers Water Resources, Reviewer/Inspector Albemarle County Department of Engineering & Public Works 401 McIntire Road, Room 211 Charlottesville, VA 22902-4596 Phone (434)296-5832 ext. 3025 Fax(434)972-4035 mchambers@albemarle.org 8/1/2005 - Page 3 of 3 Nome ‘4110 From: Phillip Custer [mailto:pcuster@mckeecarson.com] Sent: Monday, August 01, 2005 8:53 AM To: mchambers@albemarle.org Subject: A few questions regarding Waldorf School UD Design Mark- Hello. We had met earlier last week when I accompanied Eugene and Todd to your meeting to discuss the comments they got back on the Waldorf School LID project. That was Todd's last week, so another engineer and myself have taken over the design and I just wanted to run a few things by you before we submit it because I want you to only have to review this design one more time. First of all, my colleague and I are disagreeing on the method to calculate Volume needed to provide 100% retention. One method that has been used is the one outlined in Appendix A of the LID design handbook which uses Chart Series B in the LID Companion document handbook. The other method is using the modified rational method and designing retention for both the Water Quality Value and Water Quantity value because my colleague tells me that is the method primarily used in Albemarle County. Is it acceptable to design using Modified Rational Method for LID purposes? Second, is the three day drainage requirement for Bioretention filters referring to the ponded water on the surface or the complete drainage of the entire facility? Because of the large volume of water retention we are seeing on this project, we are planning on using maximum ponding depths of 1ft in our bioretention filters. Will this be accepted? I've seen maximum heights of both 6in and 1ft used in the handbook. Thanks for your time Mark. We appreciate any insight you could give us. Philip B. Custer McKee Carson 301 East High Street Charlottesville, Virginia 22902 T: 434-979-7522 F: 434-977-1194 www.mckeecarson.com www.fieldsport.com 8/1/2005 `I tir ..r I I11 or )(ye' qfk 41.• IFIL ( 11I I'1IG.\ FOR THE greenest •,c hoot in America CHARLOTTESVILLE WALDORF FOUNDATION June 23, 2005 To: Albemarle County Officials RE: Charlottesville Waldorf School LID storm water plan/curb and gutter waiver request. Dear Albemarle County Officials, This letter is a formal request to replace the curb and gutter along our travel-way and lower portion of the parking lot with a low impact design. By this we mean to utilize above-ground natural storm water attenuation practices versus conventional heavy- handed `in-the-pipe' structural methods. Our School community has strong pro-environmental convictions and is dedicated to developing this property in such a way that our presence will actually enhance the site's natural functions. We hope to accomplish this by minimizing impervious surfaces; conserving natural resources; maintaining natural drainage-ways and reducing use of underground pipes (PG Co. LID Manual; 2000; xi). Low impact development (LID) storm water practices are an integral part of this plan. Our plan calls for a super-elevated roadway sloped toward a vegetated swale along its inner curve. Water will sheet off the road into the swale, utilizing the full length of the grassy shoulder to reduce the velocity and absorb some of the storm water. Once in the swale, a reinforced channel (geotextile fabric) and native plants will serve to slow and filter the runoff and encourage further absorption. The remaining storm water will be directed into an existing detention pond which we have modified with a flatter grade and native hydric species plants. We hope to use the vegetated swale and enhanced detention pond as a didactic element in the landscape where the students can learn about both storm water and urban infrastructure. Ideally we would rather utilize a bio-retention area (similar to the proposed parking lot) rather than a detention pond. However, as the pond is already in place (as a result of a previous BMP), we find that a hybrid system of the vegetated swale and existing BMP to be the most pragmatic solution. Our plans for this property have received strong support from multiple community groups (listed below), as well as two state agencies. The Department of Forestry has identified this property as valuable under its Strategic Urban Forest Grant program and has awarded us funding to consult with the Community Design Assistance Center(CDAC) in P.O. Box 4474• Charlottesville, Virginia 22905 1 434 293 3900 I campaign©greenestschool.org I www.greenestschool.org Ni Blacksburg regarding the enhancement of the site as both a natural area and a community resource. The Department of Conservation and Recreation has also awarded us a grant (which has been matched 2 to I by our community) under its Chesapeake Bay Watershed Grant Program to implement these very LID practices, in recognition of this parcel's importance due to its relationship to Meadow Creek. Use of conventional storm water systems (i.e. curb and gutter) will forfeit our state grant. We have already mentioned using the existing detention pond on site. Though they were not pleased by this proposition, we have worked with them in designing a system that they find more suitable, i.e. the aforementioned hybrid system that does not include curb and gutter. Our list of Community Partners (from whom we have letters of support) includes the Piedmont Environmental Council, the Thomas Jefferson Planning District Commission, The Thomas Jefferson Soil and Water Conservation District, and the Charlottesville- Albemarle Community Foundation. We also have a letter dated April 2004 from the Albemarle County Department of Engineering embracing and supporting our project and praising it as "laboratory of innovation from which others can learn valuable lessons." You are no doubt well aware that Virginia gets an"F" overall in air quality rating, and that our waterways are similarly polluted, largely by run-off. We believe that the high rate of growth of our county and its popularity in national rankings should push us to pursue methods that mitigate the environmental impact of that growth. The Charlottesville Waldorf Foundation, The Charlottesville Waldorf School community, multiple greater Charlottesville-Albemarle community groups, and several State agencies all recognize the importance of adopting environmentally responsive development practices, and join us in our request to do better by this site than the curb and gutter, storm water concentration approach. Please favorably consider our request to replace it with the LID strategies McKee-Carson has designed. Sincerely, Kevin O'Brien for the Charlottesville Waldorf School JUN 24 2005 OF n rgF, Arm 4RclNt COUNTY OF ALBEMARLE Department of Planning&Community Development 401 McIntire Road,Room 218 Charlottesville,Virginia 22902-4596 (434)296-5823 Fax(434)972-4035 January 15,2003 Bruce Wardell, Architects, PC 112 4th Street, NE Charlottesville VA 22902 RE: SDP-2002-118 Charlottesville Waldorf School Preliminary Site Plan Dear Mr. Wardell: The Department of Planning and Community Development hereby grants administrative approval to the above-referenced site plan. The approval of the preliminary site plan is valid for(1) one year in accordance with Zoning Ordinance Section 32.4.3.1. Therefore, the preliminary approval shall expire January 15,2004. If the preliminary site plan approval expires, a new application must be filed and processed. Please address all of the requirements and conditions listed below and submit eight (8) tentative plan copies to the Department of Planning and Community Development. This letter must be submitted with the tentative plans,as a checklist, to document that you have addressed all requirements or conditions, or the tentative plan will be denied. A submission and review schedule is attached for your information. The Erosion and Sediment Control Plan and the BMP Stormwater Management Plan, with the associated applications and fees, may also be submitted with the eight(8) tentative Plans. Failure to do so will result in a separate application to be filed with the Engineering Department at a later date. After the initial tentative plan submittal, each department/agency will contact you to discuss any remaining conditions. After all aforementioned department/agencies have granted a tentative approval, you may submit the final mylars (2 sets), one blueprint copy, final site plan application, final site plan fee, and a copy of all written tentative approvals to the Department of Planning and Community Development by 5:00 p.m. on any Monday. Assuming that the final site plan mylars reflect all tentative approvals, signing of the plans will occur within one week. The final site plan will be subject to all final site plan requirements (Zoning Ordinance Section 32.6), in addition to the following conditions. 1. The Planning Department shall not accept submittal of the final site plan for signature until tentative approvals for the following conditions have been obtained. The final site plan shall not be signed until the following conditions are met: Sid ❑ A. Planning Department approval to include: 1. Provide two copies of a landscape plan that is in conformance with Section 32.7.9. The landscape plan should be coordinated with the utility plan to keep all new trees out of any existing and proposed utility easements; and, ❑ 2. Provide for all required landscaping, utilities, grading, Special Use Permit conditions, and other site work for each appropriate phase when submitted for final approval. ❑ 3. The road servicing this development must be labeled with an approved road name. The applicant should develop a list of several potential replacement names prior to contacting our office for road name approval. This will increase the likelihood that some of the road names on the list are approvable. ❑ 4. If necessary; before the final approval of Phase 2 the angled parking and one way vehicular circulation will need Planning Commission approval. ❑ B. Engineering Department approval to include: ❑ 1. Access must be provided for the Daniel property, TMP 61-174, through the proposed school driveway. We feel this is necessary because signal queuing along Rio Road will likely obstruct access to this home. This must be addressed with the final site plan. ❑ 2. An erosion control plan, narrative and computations. [18-32.7.4.3, 17-203]; • 3. A completed application and fee for erosion control and stormwater management. [17-203, 17-303]; ❑ 4. A stormwater management/BMP plan and computations. Computations must include water quality and detention routings for the 2yr and l0yr storms. [17-304]; ❑ 5. A completed stormwater management facilities maintenance agreement and fee. [17-323]; and, ❑ 6. Drainage computations. [18-32.7.4, Policy] ❑ C. Albemarle County Building Codes and Zoning Services approval to include: ❑ 1. If the same pupils in Phase 1 are being counted in Phase 2 then no new parking spaces would be required; therefore, the info in the chart is incorrect and confusing, please correct. ❑ 2. Please show and label the required 25' front setback adjacent to the access easement. ❑ 3. Please show the location of all proposed lighting; 4. Please provide a photograph or diagram and description of all proposed luminaires demonstrating that the luminaire is full cut-off; and, 5. Please provide a photometric plan demonstrating that all proposed luminaires do not exceed % foot-candle spillover onto public roads and adjacent rural and residentially zoned parcels. ❑ 6. If necessary,before the final approval of Phase 2 the angled parking and one way vehicular circulation will need Planning Commission approval. E. Albemarle County Service Authority Approval to include: ❑ 1. Approval of final construction drawings for the water and sewer extensions. ❑ G. Virginia Department of Transportation approval to include: f lieI O I. Adequate ingress and egress must be provided to the following parcels TMP61-171, 172, 172A, 174 at all times. The ultimate access to these parcels should be a connection to the Waldorf school entrance road, and should include such modifications to the existing driveway as are deemed necessary to ensure safe and convenient access. CI 2. Drainage computations are required. CI 3. Traffic signal improvements must be operational prior to commencement of use. L) 4. The right turn and taper must be labeled and the entrance and frontage improvements need additional details. Please contact me at your earliest convenience if you have any questions or require additional information. Sincerely, , i "Francis H. MacCall Planner Attachments: Tentative Approval Process Timeline Procedure for Final Site Plan Review Tentative Plan Submission Schedule Cc: Mark Chapelle,The Cox Company John Diven,Applicant Charlottesville Waldorf School, Owner 1 1 1 I I 1