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HomeMy WebLinkAboutCorrespondenceALL SERVIOF 33 Four Wheel Drive Rd Carbondale, Co 81823 970-309-5259 March 18, 2016 Andy Schwaller Garfield County Building and Planning Department a schwalier(cgarfield-county.com Andy, ALL SERVICE septic, LLC recently designed an Onsite Wastewater Treatment System (OWTS) for the Van Rand Park Owner's Association in Garfield County. The property is located outside of Glenwood Springs, in an area where OWTSs and wells are necessary. The legal description of the subject site is Lots 1-11, Van Rand Park Subdivision. The existing septic tanks and soil treatment area (STA) serving the business park are experiencing problems and a repair to the OWTS is necessary. There is a designated utility easement on Lot 10 of the Van Rand Park Subdivision. The easement measures 57 -feet (east and west) and 75 -feet (north and south). The proposed replacement OWTS must be entirely located within the designated easement. Additionally, this easement is located the ProBuild lumber yard. This area is subject to heavy traffic loading from machinery and vehicles transporting lumber, as well as weight from lumber stored in the area. The proposed OWTS design from ALL SERVICE septic dated November 30, 2015 is in accordance with current Garfield County On -Site Wastewater Treatment System Regulations, and specific sizing criteria for seepage pits. Design choices and sizing are in accordance with 43.10 Design Criteria — Soil Treatment Area !. Repairs 4. Seepage Pits (citations below). "When space is not available or if there are other site limitations that preclude other soil treatment area options for OWTS repairs, wide beds, deep gravel trenches, and seepage pits may be considered for repairs only." (6) `The infiltrative surface of the pit is the vertical wall area (based on dug perimeter) of the pervious strata below the inlet plus the bottom area inside the vertical cylinder." Given the commercial nature of the businesses within the Van Rand Park, the OWTS design is based on a maximum potential daily wastewater flow of 1999 gallons/day (GPD). Historic water meter readings have been recorded as an average of 900 GPD. Continued water meter readings will be required to assure the OWTS does not exceed the maximum design flow of 1999 gallons/day. Design Calculations: Average Design Flow = 1999 GPD Soil Long Term Acceptance Rate (LTAR) = 0.8 gal/SF 1999 GPD 10.8 gal/SF = 2499 SF seepage pit (not including bottom area) Under current regulation, this seepage pit must be 57 -feet long (east and west), 46 -feet wide (north and south), and a minimum of 12 -feet deep below the inlet pipes. Page 2 When the most recent version of the OWTS Regulations was adopted, there was a significant difference in sizing criteria for seepage pits (formerly referred to as drywells) from previous regulations. Under previous regulations, vertical sidewall AND the entire bottom area of the excavation was included in the infiltrative area calculations. As noted above, current regulation restricts infiltrative area sizing to vertical sidewall and only bottom area inside the vertical cylinder, which is typically 4 -feet in diameter and equals approximately 12 square feet per cylinder. Previous language in 5 CCR 1003-6, Colorado Department of Public Health and Environment Guidelines on Individual Sewage Disposal Systems, Section VIII. C. 2. c. pertaining to drywells stated "... The absorption area of the dry well shall be computed on the basis of percolation rates, or the long-term acceptance rates of each stratum penetrated. The weighted average of the results shall be used to obtain a design value. The effective area of the pit will be calculated by adding the area of the sidewalls below the horizontal inlet line and the area of the bottom of the pit, excluding any impermeable stratum penetrated..." Given this discrepancy, there is a stakeholder process currently underway to propose changes to the regulation. There have been several proposed changes in the "Seepage Pit" section, including the inclusion of bottom area for purposes of infiltrative area sizing. Proposed revisions to the current Colorado Department of Public Health and Environment Onsite Wastewater Treatment System Regulation, Regulation #43, includes "The infiltrative surface of the pit is the vertical wall area (based on dug perimeter) of the pervious strata below the inlet plus the bottom of the area excavated." A copy of the working revision dated March 16, 2016 is enclosed. Under previous regulations, a seepage pit design with a design flow of 1999 GPD and LTAR of 0.8 gal/SF would have dimensions of 32 -feet long (east and west), 32 -feet wide (north and south), and a minimum of 12 -feet deep below the inlet pipes. ALL SERVICE septic is of the opinion that a seepage pit with dimensions of 32' x 32' x 12' deep will be sufficient to accommodate design flows of up to 1999 GPD. A seepage pit sized under current code with dimensions of 57' x 46' x 12' deep not only increases the cost and complexity of the installation, but also decreases the separation distance to the existing well serving the Van Rand Park Subdivision. Additionally, the Van Rand Park Owner's Association has agreed to connect to the future Cattle Creek Metro District (River's Edge) sewer system. This future development is proposing sewer collection services in the area of the Van Rand Park. There is currently no sewer collection infrastructure available in this area. We would appreciate Garfield County's consideration to permit a seepage pit design for the Van Rand Park Owner's Association that would be inclusive of the vertical sidewall AND the entire bottom area of the excavation to calculate the infiltrative area of the STA. Please call with questions. Sincerely, ALL SERVICE septic, LLC &v (aa -&g Carla Ostberg, MPH, REHS Andy Schwaller From: Andy Schwaller Sent: Monday, March 28, 2016 3:01 PM To: 'David Dodson; Carla Ostberg Cc: Dave Malehorn Subject: RE: Van Rand Business Park OWTS sizing Based on all the input and information contained in the March 18, 2016 letter from All Service Septic, the county would approve the proposed smaller OWTS as a repair for the existing system. It would appear the actual design flows can be used and the proposed design would be in compliance with the present OWTS rules and regulations. This would limit any expansion of the facilities using the system, but the future might hold some solutions to this problem either due to a new central system or a change in the present OWTS rules and regulations. The county would require verification of the soil test with an open hole inspection. Continued water meter readings would also be required. Hopefully there will be a central system in the near future. Hook up to this system would be mandatory. Work can begin once a formal OWTS permit is submitted and issued. Thanks, Andy Schwaller Building Official Garfield County From: David Dodson {mailto:ddodson@rof.net] Sent: Monday, March 28, 2016 11:54 AM To: Carla Ostberg <carla.ostberg@gmail.com> Cc: Andy Schwaller <aschwaller@garfield-county.com>; Dave Malehorn <dave@proautogws.com> Subject: Re: Van Rand Business Park OWTS sizing Carla, the answers you provided to Andy's questions are accurate as far as I know. There is no more land or capacity to add any more businesses in the future on to our existing system. Thank you, David Dodson On Mar 25, 2016, at 12:42 PM, Carla Ostberg <carla.ostberg@2mail.com> wrote: Hi Andy, I will try to answer these questions, but am copying two of the Board members in case further clarification is necessary. 1. Why was 1999 GPD used rather than the actual flow rate of 900 GPD analysis based on 43.6 A 4 a? It would appear there is a 100% safety factor from actual flow to estimated flow based on Table 6- 2. A design flow of 1999 gallons was used due to the commercial nature of the Business Park. At any time, a business could sell and be replaced with one requiring higher water usage. It would not be feasible to modify the system each time a business sold and/or changed water usage. 2. How far is the closest water well to the proposed system and how deep is the well or do we know at what level they hit water? I have attached documents pertaining to the well. We are able to acheive 100 -feet from the proposed seepage pit to the well. If we are able to decrease the footprint to of the seepage pit, we would be able to increase the setback to approximately 125'. Excerpt from our design letter regarding the well: "State of Colorado, Office of the State Engineer Well Permit Number 036168-F documents this well. The well was originally drilled in 1988 to a depth of 115 -feet. In 2000, the well was drilled to a depth of 140 -feet." 3, Is a higher level system an option? While we recommend secondary treatment, this will be cost prohibitive for the Van Rand Business Park. I have also attached one proposal, which adds approximately $18,000 to the cost of the system. 4. It would appear the Van Rand Business Park is built out. Are there any plans or land available to add any businesses to the proposed system in the future? Possibly Dave Malehorn or Dave Dodson can better answer this question. I believe there is no capacity for additional businesses; however, businesses may change resulting in a change in water usage. Please correct me if I have not accurately addressed this question. Thanks Andy - let me know if you have more questions! On Fri, Mar 25, 2016 at 12:50 PM, Andy Schwaller<aschwaller@garfield-county.com> wrote: Hi Carla, A couple of questions: 1. Why was 1999 GPD used rather than the actual flow rate of 900 GPD analysis based on 43.6 A 4 a? It would appear there is a 100% safety factor from actual flow to estimated flow based on Table 6- 2. 2. How far is the closest water well to the proposed system and how deep is the well or do we know at what level they hit water? 3. Is a higher level system an option? 4. It would appear the Van Rand Business Park is built out. Are there any plans or land available to add any businesses to the proposed system in the future? Thanks, Andy Schwaller Building Official Garfield County 2 From: Carla Ostberg[mailto:carla.ostbere@email.comj Sent: Tuesday, March 22, 2016 11:22 AM To: Andy Schwaller<aschwaller@earfield-countv.com>; David Dodson <ddodson@rof.net>; Dave Malehorn <dave@proautogws.com> Subject: Van Rand Business Park OWTS sizing Hi Andy, Please find the attached letter regarding the Van Rand Business Park and sizing for their proposed seepage pit. Please feel free to call me with any questions. Thank you! Carla Ostberg CBO Inc. working with ALL SERVICE septic cell) 970-309-5259 office) 970-704-0484 33 Four Wheel Drive Road Carbondale, CO 81623 Carla Ostberg CBO Inc. working with ALL SERVICE septic 3 cell) 970-309-5259 office) 970-704-0484 33 Four Wheel Drive Road Carbondale, CO 81623 <well information.pdf> <well pump test and report.pdf> <well request to drill deeper.pdf> <well statement of beneficial use.pdf> <FAST 3.0 Quote for Van Rand_12.2.15.pdf>