The URL can be used to link to this page

Home My WebLink AboutOWTS Design129 Cains Lane Carbondale, CO 81623 970.309.5259 carla.ostberg@gmail.com March 26, 2022 Project No. C1701 Ryobi Foundation c/o Jill and Jesse Steindler jill@ryobifoundation.org jesse@ryobifoundation.org Subsurface Investigation and Onsite Wastewater Treatment System Design 5-Bedroom Residence 13112 Hwy 82 Garfield County, Colorado Jill and Jesse, CBO Inc. performed a subsurface investigation and completed an onsite wastewater treatment system (OWTS) design for the subject residence. The 6.3-acre property is located outside of Carbondale, in an area where OWTSs are necessary. Legal Description: Section: 27 Township: 7 Range: 88 Subdivision: RYOBI FOUNDATION PROPERTY SUBDIVISION Lot: PARCEL 3 AS PER PLAT RECEPTION Parcel ID: 2393-271-03-003 SITE CONDITIONS A 5-bedroom residence presently exists, and a building permit will be obtained for a remodel. No records on the existing OWTS were available from Garfield County. The existing septic tank was located, and it has a single compartment. The existing OWTS will be abandoned and the proposed OWTS will serve the remodeled residence. The residence is currently served by a spring located to the north of the residence. A water line runs to the west of the residence. This water line must be at least 25-feet from any OWTS component. The proposed soil treatment area (STA) location has an approximate 10% slope to the southeast. The proposed area is vegetated with native grasses and sage. There should be no traffic or staging of material over the future STA site to avoid compaction of soils prior to construction of the STA. SUBSURFACE The subsurface was investigated on March 16, 2022 by digging two soil profile test pit excavations (Test Pits). A visual and tactile soil analysis was completed by Carla Ostberg at the time of excavation.1 1 Carla Ostberg holds a Certificate of Attendance and Examination from the CPOW Visual and Tactile Evaluation of Soils Training. Page 2 The materials encountered in Test Pit #1 consisted of dark brown topsoil to 1.5-feet, underlain by light brown silt loam to a maximum depth explored 6.0-feet. No bedrock or groundwater was encountered. The horizon between 2.5-feet to 4.0-feet had weak structure grade with greater density. The materials encountered in Test Pit #2 consisted of dark brown topsoil to 1.5-feet, underlain by light brown silt loam to a maximum depth explored 7.0-feet. No bedrock or groundwater was encountered. The horizon between 1.5-feet to 3.0-feet had weak structure grade with greater density. A sample of the soils was taken from Test Pit #1. The soil formed a ball and a ribbon approximately 1- inch in length before breaking. Soil structure shape was blocky and consistence was firm. Soil texture was more smooth than gritty. Both Test Pits had a horizon with weak structure grade. STA sizing is based on Soil Type 2A, Silt Loam with weak structure grade. A long term acceptance rate (LTAR) of 0.5 gallons per square foot will be used to design the OWTS. View of Test Pit #1 looking south Test Pit #1 Page 3 Sieved sample Ribbon approx. 1-inch in length Test Pit Page 4 Test Pit #2 Page 5 DESIGN SPECIFICATIONS The existing septic tank will be abandoned by pumping and crushing the top, bottom, and sides and filling the void with onsite material. The existing STA will be abandoned in place. Design Calculations: Average Design Flow = 75 GPD x 2 people/bedroom x 5 Bedrooms = 750 GPD LTAR = 0.5 GPD/SF 750 GPD / 0.5 GPD/SF x 1.0 (gravity trenches) x 0.7 (chambers) = 1050 SF The new OWTS design is based on 5-bedrooms. An average daily wastewater flow of 750 GPD will be used. For the purposes of this OWTS design, Benchmark Elevation has been established as the sewer line exiting the residence (100’). CBO Inc. should be notified of any discrepancies or problems with grade elevations of proposed components during installation of the OWTS. OWTS Component Minimum Elevation Primary Tank Inlet Invert Approximate horizontal distance 55’ / min. 2% fall / min. 13.75” fall Distribution Box Approximate horizontal distance 21’ / min. 1% fall / min. 2.625” fall Infiltrative Surface Approximate horizontal distance to furthest trench 44’ / min. 1% fall / min. 5.5” fall *Elevations are based upon standard OWTS installation practices. Component elevations may change during installation due to site conditions. Minimum grade refers to piping between components. The sewer line existing the residence must be located. This can be done by utilizing a sewer line camera and entering the sewer line through a lower level toilet or through the sewer line as it enters the existing septic tank. Once located, a new 4-inch diameter sewer line must be installed with a double-sweep clean out and a minimum 2% grade to the septic tank. Minimum Schedule 40 strength pipe must be used under the driveway. The system installation must include a 1000-gallon, two-compartment Infiltrator® poly septic tank with an effluent filter on the outlet tee. Other state-approved concrete or poly septic tanks may be substituted. Risers must bring the manhole lids to grade for access. If more than one riser is added to the septic tank, an extension handle must be installed on the effluent filter. Effluent will gravity flow to a distribution box, and then to six gravelless chamber trenches. The distribution box must be accessible from grade and must have flow equalizers, or similar product, installed on each outlet pipe in the distribution box to assure equal flow to each bed. Each trench will consist of 15 ‘Quick 4’ Standard Plus Infiltrator® chambers for a total of 90 chambers and 1080 square feet of infiltrative area. There must be at least 4-feet of undisturbed soil between each trench. Inspection ports must be installed at the beginning and end of each trench. Ports may be cut to grade and placed in sprinkler boxes for access. Page 6 COMPONENT SPECIFICATIONS The component manufacturers are typical of applications used by contractors and engineers in this area. CBO Inc. must approve alternative components prior to installation of the OWTS. Requests must be submitted, in writing, to our office for approval prior to installation. Component technical data sheets are available upon request. COMPONENT MANUFACTURER MODEL NO. COMMENTS Septic Tank Valley Precast or Infiltrator® Item # 1000T-2CP or Item # 1060-2CP 1000-gallon, 2- compartment septic tank Risers and Lids Orenco® Double-walled PVC risers and lids Effluent Filter Orenco® 4-inch diameter Full size Distribution Box Polylok Distribution box, lids, rises, and (6) flow equalizers Chambers Infiltrator® Standard Plus 90 ‘Quick 4’ Construction must be according to Garfield County On-Site Wastewater Treatment System Regulations, the OWTS Permit provided by Garfield County Building Department, and this design. INSTALLATION CONTRACTOR CBO Inc. expects that the installer be experienced and qualified to perform the scope of work outlined in this design. The installer must review this design thoroughly and coordinate with our office in advance of installation. Any additional conditions in this design or county permit must be completed and documented prior to final approval of the OWTS installation. Communication between the installer and this office is expected throughout the installation. INSTALLATION OBSERVATIONS CBO Inc. must view the OWTS during construction. The OWTS observation should be performed before backfill, after placement of OWTS components. Septic tanks, distribution devices, pumps, dosing siphons, and other plumbing, as applicable, must also be observed. CBO Inc. should be notified 48 hours in advance to observe the installation. In an effort to improve the accuracy of the record drawing, we request that the installer provide a sketch of the installation, including path of the sewer lines, water line installation (if applicable), septic tank location, STA location, and measurements from building corners or another fixed objects on the property. This sketch is most easily provided on Sheet W2.0 of the OWTS Design Packet. Photographs of the installation and final cover are also requested to supplement our installation documentation. REVEGETATION REQUIREMENTS An adequate layer of good quality topsoil capable of supporting revegetation shall be placed over the entire disturbed area of the OWTS installation. A mixture of native grass seed that has good soil stabilizing characteristics (but without taproots), provides a maximum transpiration rate, and competes well with successional species. No trees or shrubs, or any vegetation requiring regular irrigation shall be placed over the STA. Until vegetation is reestablished, erosion and sediment control measures shall be implemented and maintained on site. The owner of the OWTS shall be responsible for maintaining proper vegetation cover. Page 7 OPERATION INFORMATION AND MAINTENANCE The property owner shall be responsible for the operation and maintenance of each OWTS servicing the property. The property owner is responsible for maintaining service contracts for manufactured units, alternating STAs, and any other components needing maintenance. Geo-fabrics or plastics should not be used over the STA. No heavy equipment, machinery, or materials should be placed on the backfilled STA. Machines with tracks (not wheels) should be used during construction of the STA for better weight distribution. Livestock should not graze on the STA. Plumbing fixtures should be checked to ensure that no additional water is being discharged to OWTS. For example, a running toilet or leaky faucet can discharge hundreds of gallons of water a day and harm a STA. If an effluent filter or screen has been installed in the OWTS, we recommend this filter or screen be cleaned annually, or as needed. If the OWTS consists of a pressurized pump system, we recommend the laterals be flushed annually, or as needed. The homeowner should pump the septic tank every two years, or as needed gauged by measurement of solids in the tank. Garbage disposal use should be minimized, and non-biodegradable materials should not be placed into the OWTS. Grease should not be placed in household drains. Loading from a water softener should not be discharged into the OWTS. No hazardous wastes should be directed into the OWTS. Mechanical room drains should not discharge into the OWTS. The OWTS is engineered for domestic waste only. ADDITIONAL CONSTRUCTION NOTES If design includes a pump, weep holes must be installed to allow pump lines to drain to minimize risk of freezing. The pump shall have an audible and visual alarm notification in the event of excessively high- water conditions and shall be connected to a control breaker separate from the high-water alarm breaker and from any other control system circuits. The pump system shall have a switch so the pump can be manually operated. Excavation equipment must not drive in the excavation of the STA due to the potential to compact soil. Extensions should be placed on all septic tank components to allow access to them from existing grade. Backfill over the STA must be uniform and granular with no material greater than minus 3-inch. LIMITS: The design is based on information submitted. If soil conditions encountered are different from conditions described in report, CBO Inc. should be notified. All OWTS construction must be according to the county regulations. Requirements not specified in this report must follow applicable county regulations. The contractor should have documented and demonstrated knowledge of the requirements and regulations of the county in which they are working. Licensing of Systems Contractors may be required by county regulation. Please call with questions. Sincerely, CBO Inc. Carla Ostberg, MPH, REHS 13112 Hwy 82 Legend 650 Lion's Ridge Rd 100 ft N➤➤N Garfield County, CO Developed by Account Number R084005 Par cel Number 239327103003 Acr es 6 Land SqFt 0 T ax Ar ea 011 2019 Mill Levy 79.7760 Physical A ddr ess 13112 82 HWY C ARBONDALE 81623 Owner Addr ess RYO BI FOUNDATION 13110 HIGHWAY 82 C ARBONDALE C O 81623 2019 Total Actual Value $976,650 La st 2 Sales Date Pr ice 8/21/2017 $0 8/21/2017 $0 Date created: 1/30/2022 Last Data Uploa ded: 1/29/2022 2:04:48 AM 461 ft Overvi ew Legend Parcels Roa ds Parcel/Account Number s Highw ays Limited Access Highwa y Major Road Loca l Roa d Minor Road Other Road Ra mp Ferry Pedestria n Way Owner Na me Lakes & River s County Boundar y Line