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Home My WebLink AboutC1860 OWTS Design Packet 1 30 24129 Cains Lane Carbondale, CO 81623 970.309.5259 carla.ostberg@gmail.com January 30, 2024 Project No. C1860 Todd Christman todd@unionpropertycapital.com Subsurface Investigation and Onsite Wastewater Treatment System Design 4-Bedroom Residence 5970 CR 109 Garfield County, Colorado Todd, CBO Inc. performed a subsurface investigation and completed an onsite wastewater treatment system (OWTS) design for the subject residence. The 2.437-acre property is located outside of Carbondale, in an area where OWTSs and wells are necessary. Legal Description: Section: 28 Township: 7 Range: 88 Subdivision: SNOBBLE EXEMPTION Lot: A AMENDED 2.438 ACRES Parcel ID: 2393-283-18-001 SITE CONDITIONS The property is currently developed with a 5-bedroom residence and served by an existing OWTS. The structure will be re-built with a new, 4-bedroom residence and will be served by the proposed OWTS described in this design. The residence will be served by a private well on the property. The existing well will be abandoned and a new well drilled to the south of the proposed residence. We have approximated the well location on our site plan. The well will be located greater than 50-feet from the proposed septic tank and greater than 100-feet from the proposed soil treatment area (STA). The proposed mounded soil treatment area (STA) will be built into an existing hillside to an elevation at least 3-feet above high seasonal groundwater. A portion of the proposed mounded sand filter extends into the 100-year floodplain; however, the height of the infiltrative area of the mound will be outside of the floodplain elevation. The existing STA is located in the same approximate area as the proposed base of the mounded sand filter. 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. Page 2 SUBSURFACE The subsurface was investigated on December 13, 2015 by digging one soil profile test pit excavation (Test Pit). Only one Test Pit was excavated due to the presence of groundwater in the Test Pit. A visual soil analysis was completed by Carla Ostberg at the time of excavation.1 The soil was very wet to saturated, and the existing STA was encountered. The materials encountered in the Test Pit consisted of dark brown, moist, organic topsoil to 1.5-feet, underlain with medium brown, moist, loamy sand to 3-feet, underlain by a gray, moist to saturated organic horizon (which is likely the existing STA) to 4-feet, underlain by gravel and cobbles to a maximum depth explored of 6-feet. Groundwater entered the pit at approximately 3-feet below grade at the time of excavation. Given the location of the flood plain, the proximity to the river, and time of year, we estimate high seasonal groundwater at the ground surface. STA sizing is based on Soil Type R-1 with a minimum of 3-feet of sand filter material. A long term acceptance rate (LTAR) of 0.8 gallons per square foot will be used to design the OWTS. Test Pit Note groundwater entering test pit at approx. 3’ 1 Carla Ostberg holds a Certificate of Attendance and Examination from the CPOW Visual and Tactile Evaluation of Soils Training. Page 3 Backfill, very wet View of test pit and edge of bank DESIGN SPECIFICATIONS The existing septic tank will be abandoned by pumping the tank and removing it. The existing STA will be abandoned in place. Design Calculations: Average Design Flow = 75 GPD x 2 people/bedroom x 3 Bedrooms + 75 GPD (4th Bedroom) = 525 GPD LTAR = 0.8 GPD/SF 525 GPD / 0.8 GPD/SF = 656.25 SF The OWTS design is based on 4-bedrooms. An average daily wastewater flow of 525 GPD will be used. For the purposes of this OWTS design, Benchmark Elevation at grade 6101’ has been established as 100’ (Finished Floor). CBO Inc. should be notified of any discrepancies or problems with grade elevations of proposed components during installation of the OWTS. Page 4 OWTS Component Minimum Elevation Primary Tank Inlet Invert Approximate horizontal distance 16’ / min. 2% fall / min. 4” fall Automatic Distributing Valve Approximate horizontal distance 3’ / min. 1% rise / min. 0.375” rise Infiltrative Surface Approximate horizontal distance 21’ / min. 1% fall to STA / min. 2.625” 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. A new, 4-inch SDR-35 sewer line exiting the residence must have a double-sweep clean out and a minimum 2% grade to the septic tank. The system installation will include a minimum 1250-gallon, two-compartment septic tank with an Orenco® Biotube Effluent filter on the outlet tee. Any state-approved concrete or poly septic tank may be used. We have specified a 1500-gallon, two-compartment Infiltrator® poly septic tank as they are locally available. A 500-gallon, single-compartment Infiltrator® poly pump chamber with an Orenco® Biotube Pump Vault and an Orenco® PF3005 pump will follow. The floats should be set to dose approximately 78 gallons each pump cycle, allowing approximately 1 gallon of drain back. The control panel for the pump must be located within line of sight of the septic tank. An electrician will be responsible for wiring the pumping system and the contractor will be responsible for connecting the plumbing. This office should be contacted for start up of the system to verify its functioning and to perform a squirt test prior to use of the system. Pump Table Dose Range Max = 132.25 gal. (525 GPD x 25% + 1 gal drain back) Min. 53 gal. (13 gal x 4) + 1 gal drain back Dose Setting 78 gallons/dose 1 gallon drain back (3’ / 1.5” diameter pump line) Float Separation 500 gallon, single-compartment Infiltrator® poly pump chamber 6” on/off float separation Pump Criteria 23.1 gallons per minute (GPM) 16.7 feet total dynamic head (TDH) Effluent will be pressure dosed through a 1.5-inch diameter pump line to a mounded, unlined sand filter. The mound will be positioned against the existing 6-foot high bank to blend the mounded area into the topography on the property. The topsoil horizon (18-inches) must be scraped from the base of the 13’ x 50.5’ mound and replaced with sand filter material. If any saturated soils from the existing STA are encountered, they should be removed and staged for drying prior to disposal at a landfill. The mound will consist of a minimum of 3-feet of sand filter material above native grade. Sand filter material must be clean, coarse sand, all passing a screen having four meshes to the inch. The sand must have an effective size between 0.25 and 0.60 mm. The uniformity coefficient must be 4.0 or less. Material meeting ASTM 33, for concrete sand, with one percent or less fines passing 200 mesh sieve may be used. A gradation of the sand media must be provided. Effluent will be pumped through a 1.5-inch diameter pump line from the pump chamber to an Orenco® automatic distributing valve (ADV), model 6402. The pump line must have a minimum 1% grade for proper drain back into the tank after each pump cycle. The ADV must be placed at a high point in an insulated riser with access from grade. Screened rock must be placed below the ADV to support the ADV and to assure the clear pipes exiting the ADV remain visible for future inspection and maintenance. Level, 1.5-inch diameter manifolds will connect two laterals in each zone (see W3.0/1 Mounded Sand Filter Plan). Laterals must be 1.5-inches in diameter with 5/32-inch diameter orifices facing down, spaced 3- feet on center, installed on the GeoMat™ with the filter fabric over the laterals. Laterals should be placed 2- Page 5 feet from the edges of the bed leaving 3’ between center of laterals. Four 39” wide GeoMat™ must be placed on the 13-foot wide bed. All material associated with the GeoMat™ installation must be proprietary products associated with the GeoMat™, including orifice shields and geotextile fabric. Manufacturer instructions must be followed regarding installation of the GeoMat™. Each 1.5-inch diameter lateral must end in a sweeping ell facing up with a ball valve for flushing. Laterals must be covered by the gray Geomat™ soil separation fabric and at least 1-foot of topsoil or other suitable soil able to support vegetative growth. There shall be no cobble-sized (2.5”) or greater rock in final cover over the GeoMat™. Inspection ports must be placed into the sand filter material on each corner of the beds. The mound must have a minimum 3:1 slope (horizontal:vertical); therefore, the basal area will extend approximately 10.5-feet beyond the sand filter on all sides (with a mound height of approximately 3.5-feet above native grade). Soils in the sloped perimeter areas of the mound must be well draining and able to support vegetative growth. This soil must be approved by this office prior to installation. The mound must be crowned in a manner to promote drainage off the STA. The mound must have a minimum 3:1 slope (horizontal: vertical); therefore, the basal area will extend 12- feet beyond the sand filter on all sides, with the exception of the side of the mound bordered by the existing bank. Proposed disturbed areas below elevation 6088’ should be armored with All American Green SC250 erosion fabric covered with 3-inches of topsoil and reseeded with native grasses. 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 Infiltrator® IM-1530-2CP Min. 1250-gallon, two- compartment poly septic tank (1500-gallons locally available) Effluent Filter Orenco® Full size filter Pump Chamber Infiltrator® IM-540-HH 500-gallon, single- compartment poly pump chamber with high head pump Pump Orenco® PF500511 ½ HP 120 Volt 50 gpm pump Biotube ProPak Pump Package Orenco® BPP30DD Vault, Filter, Control Panel (demand dose) Tank Risers and Lids Orenco® Double-walled PVC Risers and Lids (24” diameter) ADV Orenco® V6402A 1.5” Inlet and Outlets ADV Riser and Lid Orenco® Double-walled PVC Risers and Lids (30” diameter) Flushing Assembly Orenco® 1.5” diameter (2) 45° or 90° long sweep only (4 total) GeoMat™ GeoMatrix Systems, LLC 202’ GeoMat™ (39”) and 64 Orifice Shields Page 6 Construction must be according to the jurisdiction’s adopted On-Site Wastewater Treatment System Regulations, the OWTS Permit, and this design. PERMIT APPLICATION INSTRUCTIONS An OWTS Permit Application must be submitted to Garfield County Environmental Health Department. https://www.garfield-county.com/environmental-health/filesgcco/sites/16/OWTS-Application-Complete- Packet-Dec.-2019.pdf. If the OWTS Permit Application will be submitted with a Building Permit Application, it should be submitted directly to Garfield County Building Department. All questions regarding permit submission can be directed to Garfield County Environmental Health Department, 970-945-6614 x8150. 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. 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 Page 7 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 Pump Selection for a Pressurized System - Single Family Residence Project Christman Parameters Discharge Assembly Size Transport Length Before Valve Transport Pipe Class Transport Line Size Distributing Valve Model Transport Length After Valve Transport Pipe Class Transport Pipe Size Max Elevation Lift Manifold Length Manifold Pipe Class Manifold Pipe Size Number of Laterals per Cell Lateral Length Lateral Pipe Class Lateral Pipe Size Orifice Size Orifice Spacing Residual Head Flow Meter 'Add-on' Friction Losses 1.25 3 40 1.50 6402 21 40 1.50 2 3 40 1.50 4 49.5 40 1.50 5/32 3 5 None 0 inches feet inches feet inches feet feet inches feet inches inches feet feet inches feet Calculations Minimum Flow Rate per Orifice Number of Orifices per Zone Total Flow Rate per Zone Number of Laterals per Zone % Flow Differential 1st/Last Orifice Transport Velocity Before Valve Transport Velocity After Valve 0.68 34 23.1 2 1.5 3.7 3.7 gpm gpm % fps fps Frictional Head Losses Loss through Discharge Loss in Transport Before Valve Loss through Valve Loss in Transport after Valve Loss in Manifold Loss in Laterals Loss through Flowmeter 'Add-on' Friction Losses 3.7 0.1 5.0 0.7 0.0 0.2 0.0 0.0 feet feet feet feet feet feet feet feet Pipe Volumes Vol of Transport Line Before Valve Vol of Transport Line After Valve Vol of Manifold Vol of Laterals per Zone Total Vol Before Valve Total Vol After Valve 0.3 2.2 0.3 10.5 0.3 13.0 gals gals gals gals gals gals Minimum Pump Requirements Design Flow Rate Total Dynamic Head 23.1 16.7 gpm feet 0 10 20 30 40 50 60 70 800 20 40 60 80 100 120 140 160 Net Discharge (gpm) PumpData PF5005 High Head Effluent Pump 50 GPM, 1/2HP 115/230V 1Ø 60Hz, 200/230V 3Ø 60Hz PF5007 High Head Effluent Pump 50 GPM, 3/4HP 230V 1Ø 60Hz, 200/230/460V 3Ø 60Hz PF5010 High Head Effluent Pump 50 GPM, 1HP 230V 1Ø 60Hz, 200/460V 3Ø 60Hz PF5015 High Head Effluent Pump 50 GPM, 1-1/2HP 230V 1Ø 60Hz, 200V 3Ø 60Hz Legend System Curve: Pump Curve: Pump Optimal Range: Operating Point: Design Point: 5970 CR 109 Legend 5970 Co Rd 109 100 ft N ➤➤ N Garfield County, CO Developed by Account Number R083584 Par cel Number 239328318001 Acr es 2 Land SqFt 0 T ax Ar ea 010 2019 Mill Levy 79.7800 Physical Addr ess 5970 109 C OUNTY RD C ARBONDALE 81623 Owner Addr ess BAZLEY, C AMERON 5970 C OUNTY ROAD 109 C ARBONDALE C O 81623 2019 T ota l Actual Value $607,270 La st 2 Sales Date Pr ice 5/2/2022 $0 5/10/2021 $0 Date created: 5/29/2022 Last Data Uploa ded: 5/28/2022 2:05:36 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