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Home My WebLink AboutOWTS Report 04.13.2023129 Cains Lane Carbondale, CO 81623 970.309.5259 carla.ostberg@gmail.com April 13, 2023 Project No. C1802 Redd Summit Ranches c/o Desmyn Swensen desmyn@reddsummit.com Subsurface Investigation and Onsite Wastewater Treatment System Design 3-Bedroom Residence 5905 CR 233 Garfield County, Colorado Desmyn, CBO Inc. performed a subsurface investigation and completed an onsite wastewater treatment system (OWTS) design for the subject residence. The 10-acre property is located outside of Silt, in an area where OWTSs are necessary. Legal Description: Section: 35 Township: 5 Range: 92 SESESW. ANTLERS ORCHARD TR 60 Parcel ID: 2127-353-00-063 SITE CONDITIONS The property is currently developed with a 3-bedroom residence. The residence is served by an existing un-permitted OWTS that was installed in the last several years. While this system is new, the groundwater table has risen in this area due to upgradient runoff and/or the infrastructure that directs the spring water from the north to the east has been damaged. The rise in groundwater table may have damaged the new Roth® poly septic tank (it has shifted and is tilted and no longer level) and has saturated the STA. We previously designed an OWTS for this property in the Fall of 2020 which was not permitted or installed. At that time, the groundwater table in the area of the existing soil treatment area (STA) was approximately 7.0-feet below grade. Depth to groundwater at the time of our site visit on April 6, 2023 was approximately 2 to 2.5-feet below grade in the area of the existing STA. Page 2 While we are proposing the STA be moved to a higher elevation on the property, we strongly recommend mitigation efforts to intercept upgradient runoff and spring water to direct it to the east and away from the residence. A civil engineer may be necessary to determine the most effective mitigation efforts. The residence will continue to be served potable water from the spring located to the north. The approximate location of the water line from the spring is located to the north of the residence, running through an agricultural field. The new STA must be at least 25-feet from this water line. The proposed soil treatment area (STA) location has an approximate ten percent slope to the east. The proposed area is vegetated with native grasses. 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 September 2, 2020 by digging two soil profile test pit excavation (Test Pits). A visual and tactile soil analysis was completed by Carla Ostberg at the time of excavation.1 The materials encountered in Test Pit #1 consisted of dark brown silty clay loam to a maximum depth explored of 8.5-feet. Soils were increasingly moist with depth. No bedrock or groundwater was encountered. The materials encountered in Test Pit #2 were consistent with those encountered in Test Pit #1. Test Pit #2 was excavated to a maximum depth explored of 8.0-feet. Soils were increasingly moist with depth, although less moisture was observed in Test Pit #2 than in Test Pit #1. No bedrock or groundwater was encountered. An existing excavation (referenced as Test Pit #3) encountered groundwater at 8.0-feet below grade. For purposes of this design, we are estimating high seasonal groundwater at 7.0-feet below grade. A tactile analysis of the soils was taken from Test Pit #1 at 3-feet below grade. Soil structure grade was moderate. The soil formed a ball and a ribbon 1 to 2-inches in length before breaking. Soil structure shape was blocky and consistence was friable. Soil texture was more smooth than gritty. 1 Carla Ostberg holds a Certificate of Attendance and Examination from the CPOW Visual and Tactile Evaluation of Soils Training. Page 3 Test Pit #1 to the west of the driveway Page 4 Increasing moisture at bottom of Test Pit #1 Sieved sample ribbon between 1 and 2 inches Page 5 Test Pit #2 Page 6 Moisture in bottom of Test Pit #2 An additional Test Pit was excavated on April 6, 2023. The materials encountered in Test Pit #4 consisted of dark brown silt clay loam to a maximum depth explored of 6.0-feet. No bedrock or groundwater was encountered. Looking east toward where the runoff and /or spring may be saturating soils at a low point on the property. Page 7 Looking south from the approximate location of the spring line toward the proposed STA Test Pit #4 Page 8 Test Pit #4 Backfill The proposed area is out of the low-lying areas on the property and will be a drier location for the STA. STA sizing is based on Soil Type 3, Silty Clay Loam with moderate structure grade. A long term acceptance rate (LTAR) of 0.35 gallons per square foot will be used to design the OWTS. DESIGN SPECIFICATIONS The existing septic tank will be abandoned by pumping the tank and removing it or crushing the top, bottom, and sides and filling in the void with onsite materials. The existing STA will be abandoned in place. Design Calculations: Average Design Flow = 75 GPD x 2 people/bedroom x 3 Bedrooms = 450 GPD LTAR = 0.35 GPD/SF 450 GPD / 0.35 GPD/SF = 1286 SF 1286 SF x 0.8 (pressure dosed chambers) x 0.7 (chambers) = 720 SF The OWTS design is based on 3-bedrooms. An average daily wastewater flow of 450 GPD will be used. For the purposes of this OWTS design, Benchmark Elevation has been established as 100’ as the existing sewer line exiting the residence. 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 26’ / min. 2% fall / min. 6.5” fall Automatic Distributing Valve Approximate horizontal distance 138’ / min. 1% rise / min.17.25” rise Infiltrative Surface Approximate horizontal distance to furthest trench 28’ / min. 1% fall to STA / min. 3.5” 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 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. Page 9 The system installation will include a 1000-gallon, two-compartment Infiltrator® poly septic tank with an Orenco® Effluent Filter on the outlet tee followed by a 500-gallon, single-compartment Infiltrator® poly pump chamber with an Orenco® Biotube Pump Vault and an Orenco® PF3005 pump. The floats should be set to dose approximately 75 gallons each pump cycle, allowing approximately 15 gallons of drain back. The control panel for the pump must be located within line of sight of the septic tank. We recommend Valley Precast out of Buena Vista be contracted for start-up of the pumping system. Pump Table Dose Range Max = 128.5 gal. (450 GPD x 25% + 15 drain back) Min. 52 gal. (9 gal x 4) + 16 gal drain back Dose Setting 75 gallons/dose 16 gallons drain back (214’ / 1.5” diameter pump line) Float Separation 500 gallon single-compartment Infiltrator® poly pump chamber 6” on/off float separation Pump Criteria 14.3 gallons per minute (GPM) 21.9 feet total dynamic head (TDH) Effluent will be pumped through a 1.5-inch diameter pump line from the pump chamber to an Orenco® automatic distributing valve (ADV), model 6404. This pump line must have a minimum 1% grade for proper drain back into the tank after each pump cycle. We recommend Schedule 40 conduit be installed for the pump line under the driveway (W4.0/4 Encasement Detail). The ADV must be placed at a high point in the system 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. Effluent will be pressure dosed through 1.5-inch diameter pipes to four gravelless chamber trenches, each 15 ‘Quick 4’ Plus Standard Low Profile Infiltrator® chambers, for a total of 60 chambers and 720 square feet of infiltrative area. There must be at least 4-feet of undisturbed soil between each trench. Installation of the chambers should be as shallow as possible, with an approximate infiltrative area 2-feet below native grade. Effluent will be pressure dosed to 1.5-inch diameter laterals, which must be hung with zip ties from the underside of the chambers. Laterals will have 5/32-inch diameter orifices facing up, with the exception of the first and last orifices facing down for drainage. Orenco® Orifice Shields may be placed under each downward-facing orifice. The orifices must be placed 3-feet on center. Each lateral must end in a 90 degree ell facing up with a ball valve for flushing. Valves may be placed in a valve box, accessible from grade, for access. Inspection ports must be placed at the beginning and end of each trench. Ports may be cut to grade and covered with a valve box for access. 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 1060-2CP 1000-gallon, 2- compartment poly septic tank Effluent Filter Orenco® 4-inch diameter effluent filter (Full Size) Page 10 Pump Chamber Infiltrator® IM 540-HH 500-gallon, single- compartment poly pump chamber Pump Orenco® PF300511 ½ HP 120 Volt 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® V6404A 1.5” Inlet and Outlets ADV Riser and Lid Orenco® Double-walled PVC Risers and Lids (30” diameter) Orifice Shields Orenco® 8 orifice shields Flushing Assembly Orenco® 1.5” diameter (2) 45° or 90° long sweep only (4 total) Chambers Infiltrator® ‘Quick 4’ 60 ‘Quick 4’ Standard Plus Low Profile chambers 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. Page 11 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 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. Page 12 Please call with questions. Sincerely, CBO Inc. Carla Ostberg, MPH, REHS Pump Selection for a Pressurized System - Single Family Residence Project 5905 CR 233 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 1.25 138 40 1.50 6404 28 40 1.50 10 0 40 1.50 4 60 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 21 14.3 1 2.7 2.3 2.3 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 1.4 1.8 2.9 0.4 0.0 0.3 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 14.6 2.9 0.0 6.3 14.6 9.3 gals gals gals gals gals gals 14.3 21.9 gpm feet 0 5 10 15 20 25 30 35 40 0 50 100 150 200 250 300 Net Discharge (gpm) PumpData PF3005 High Head Effluent Pump 30 GPM, 1/2HP 115/230V 1Ø 60Hz, 200V 3Ø 60Hz PF3007 High Head Effluent Pump 30 GPM, 3/4HP 230V 1Ø 60Hz, 200/460V 3Ø 60Hz PF3010 High Head Effluent Pump 30 GPM, 1HP 230V 1Ø 60Hz, 200/460V 3Ø 60Hz PF3015 High Head Effluent Pump 30 GPM, 1-1/2HP 230V 1Ø 60Hz, 200/230/460V 3Ø 60Hz Legend System Curve: Pump Curve: Pump Optimal Range: Operating Point: Design Point: 5905 CR 233 Legend 5905 Co Rd 233 200 ft N➤➤N DocuSign Envelope ID: 9CF370F9-3FAC-46B7-B8E2-3287BA04A191 Garfield County, CO Developed by Account Number R200724 Par cel Number 212735300063 Acr es 10 Land SqFt 0 T ax Ar ea 020 2019 Mill Levy 66.3370 Physical A ddr ess 5905 233 C OUNTY RD SILT 81652 O w ner Addr ess REDD SUMMIT RANC HES LL C PO BO X 62 SPANISH FORK UT 84660 2019 Total Actual Value $282,930 Last 2 Sales Date Pr ice 3/15/2023 $540,000 11/17/2004 $310,000 Date created: 4/13/2023 Last Data Uploa ded: 4/13/2023 2:08:02 AM 748 ft Overvi ew Legend Parcels Roa ds Parcel/Account Number s Owner Na me Lakes & River s County Boundar y Line