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HomeMy WebLinkAboutOWTS Design Report 05.15.2025129 Cains Lane Carbondale, CO 81623 970.309.5259 carla.ostberg@gmail.com May 15, 2025 Project No. C1958 Scott Sutherland sutherland1011@gmail.com Subsurface Investigation and Onsite Wastewater Treatment System Design 4-Bedroom Residence 1430 Mineota Drive Garfield County, Colorado Scott, CBO Inc. performed a subsurface investigation and completed an onsite wastewater treatment system (OWTS) design for the subject residence. The 10.029-acre property is located outside of Silt, in an area where OWTSs are necessary. Legal Summary: Section: 14 Township: 6 Range: 92 Subdivision: MINEOTA RIDGE EST. 1ST. Lot: 01 Parcel ID: 2179-143-00-001 SITE CONDITIONS The property is currently developed with a 4-bedroom residence. The residence is served by an existing OWTS that is experiencing performance issues and there is a desire to replace the system. The existing system consists of a 1000-gallon, two-compartment Copeland concrete septic tank followed by a 24’ x 42’ pipe and gravel soil treatment area (STA) with 3’ of gravel under the perforated pipe. Garfield County Individual Sewage Disposal System (ISDS) Permit 651 documents this system. The system was sized to accommodate 3 bedrooms. The permit received final approval on April 19, 1979. The residence is served potable water community water system. The water line enters the property from the subdivision road. There is an existing ranch hydrant on the east side of the driveway that is tied into the water line, which makes the water line location evident on site but was not provided on the site plan available to us. The water line is greater than 25-feet from the proposed STA. The topography of the STA is slightly variable and the proposed area has a slightly higher elevation than a low point between the residence and the proposed STA. The alignment of the trenches must be shot for a level installation and grading over the trenches may be necessary to minimum the difference in burial depth over the length of the trenches. The area is sparsely vegetated with sage and 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. Page 2 SUBSURFACE The subsurface was investigated on May 9, 2025 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 The materials encountered in Test Pit #1 consisted of light brown clay loam to 2-feet, underlain by light brown, dense clay loam to a maximum depth explored of 7.0-feet. 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 7.0-feet. No bedrock or groundwater was encountered. A sample of the soil was taken from Test Pit #1 at 3-feet below grade. Soil structure grade was weak below 2-feet. The soil formed a ball and a ribbon 1 to 2-inches in length before breaking. Soil structure shape was blocky and consistence was firm. Soil texture was both gritty and smooth. The soil is consistent with Soil Type 3A, Clay Loam, with weak structure grade. A long-term acceptance rate (LTAR) of 0.3 gallons per square foot will be used to design the STA. Approx. STA Change in elevation between house and STA Difference is more minor further to the north 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 Sieved sample Ribbon 1 to 2-inches weak structure grade below 2’ Backfill Test Pit #2 Page 4 Knoll increases in elevation further north Test Pit #2 Backfill 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 + 75 GPD (4th Bedroom) = 525 GPD LTAR = 0.3 GPD/SF 525 GPD / 0.3 GPD/SF = 1750 SF x 1.0 (chamber trenches) x 0.7 (chambers) = 1225 SF 1225 SF / 12 SF/chamber = min. 102 ‘Quick 4’ Infiltrator® chambers 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 has been established as 100’ (existing sewer line elevation). CBO Inc. should be notified of any discrepancies or problems with grade elevations of proposed components during installation of the OWTS. Page 5 OWTS Component Minimum Elevation Primary Tank Inlet Invert Approximate horizontal distance 73’ / min. 2% fall / min. 18.25” fall Distribution Box Approximate horizontal distance 93’ / min. 1% fall / min. 11.625” fall Infiltrative Surface Approximate horizontal distance 44’ / min. 1% fall to STA / 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 will be replaced beginning at the foundation. 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. The system installation must include a 1500-gallon, two-compartment Infiltrator® poly septic tank with an Orenco® Biotube effluent filter on the outlet tee. 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 trench. Each trench will consist of 17 ‘Quick 4’ Standard Plus Infiltrator® chambers for a total of 102 chambers and 1224 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. 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 1500-gallon, two- compartment poly septic tank Effluent Filter Orenco® 4” diameter full size filter Tank Risers and Lids Orenco® Double-walled PVC Risers and Lids (24” diameter) Distribution Box Polylok Distribution box, risers, lid, flow equalizers (6) Chambers Infiltrator® ‘Quick 4’ Plus Standard Chamber 102 ‘Quick 4’ chambers Construction must be according to the jurisdiction’s adopted On-Site Wastewater Treatment System Regulations, the OWTS Permit, and this design. Page 6 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 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. Page 7 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 THE LOCATION OF PROPOSED IMPROVEMENTS SHOWN ARE NOT THE RESULT OF A PROPERTY SURVEY. THE LOCATIONS ARE APPROXIMATE. IT IS THE HOMEOWNERS' DUTY TO ENSURE ALL CONSTRUCTION AND IMPROVEMENT LOCATIONS ARE ACCURATE. PROPERTY LINES AND SETBACK DISTANCES SHOULD BE CONFIRMED PRIOR TO EXCAVATION. SCALED FOR PRINTING ON 11" X 17" PAPER. PROPERTY LINE 4-BEDROOM RESIDENCE MINEOTA DRIVE K I O W A D R I V E STA D R I V E W A Y TP 1 TP 2 APPROX. WATER LINE Sutherland Residence 1430 Mineota Drive Garfield County, Colorado Project Number: C1958 Date: 05/15/2025 Designed by: CBO Reviewed by: KC Drawn by: DD Sheet 1 0F 4 W1.0 DRAWINGS MUST BE USED IN CONJUNCTION WITH DESIGN LETTER DATED 05/15/2025 CBO Inc. 129 Cains Lane Carbondale, Colorado 81623 Phone 970.309.5259 carla.ostberg@gmail.com N 0 25' 50' SCALE: 1 = 50'=0" PROPERTY LINE 70.5' 38' 4" DIA SDR-35 INSPECTION PORT AT BEGINNING AND END OF EACH TRENCH 4" DIA SDR-35 DISTRIBUTION LINE TO EACH TRENCH (MIN. 1% SLOPE TO TRENCH) 4" DIA SDR-35 SEWER LINE TO STA (MIN. 1% FALL TO STA) DISTRIBUTION BOX WITH ACCESS AT GRADE 4" DIA SDR-35 SEWER PIPE WITH CLEANOUT MIN 2% FALL TO TANK 1500-GALLON, TWO-COMPARTMENT SEPTIC TANK WITH EFFLUENT SCREEN 4-BEDROOM RESIDENCE TP 1 TP 2 D R I V E W A Y BM 100' YARD EXISTING SEPTIC TANK TO BE ABANDONED EXISTING STA TO BE ABANDONED APPROX. WATER LINE NOTE: THE STA MUST BE ORIENTED TO FOLLOW THE TOPOGRAPHY APPROX. 94' 3" (GROUND SURFACE) APPROX. 91'6" (GROUND SURFACE) APPROX. 91'6" (GROUND SURFACE) 'QUICK-4' CHAMBER TRENCHES. 6 TRENCHES WITH 17 CHAMBERS PER TRENCH FOR A TOTAL OF 102 CHAMBERS AND 1224 SF. Sutherland Residence 1430 Mineota Drive Garfield County, Colorado Project Number: C1958 Date: 05/15/2025 Designed by: CBO Reviewed by: KC Drawn by: DD Sheet 2 0F 4 W2.0 CBO Inc. 129 Cains Lane Carbondale, Colorado 81623 Phone 970.309.5259 carla.ostberg@gmail.com N 0 10' 20' SCALE: 1 = 20'=0" 1430 M in eota Drive Legend 1430 Mineota Dr 200 ft N ➤➤ N Image © 2025 A irbus Image © 2025 A irbus Image © 2025 A irbus J This does not constitute a building or use permit. GARFIELD COUNTY DEPARTMENT OF ENVIRONMENTAL HEALTH 2014 Blake Avenue Glenwood Springs, Colorado 81601 Phone (303) 945 -7255 INDIVIDUAL SEWAGE DISPOSAL PERMIT N•651 Owner Mid Mountain Inc. Gilbert Lowie) System Location Lot 1, Piling 1, Minota Ridge Licensed Contractor Eaca, t. pr. 1/4 _,/ C4 , / Conditional Construction approval is hereby granted for a /Q. gallon X Septic Tank or Aerated treatment unit. A bsorption area (or dispersal area) computed as follows: Perc rate of one inch in 649 minutes requires a minimum of 3 0 sq. ft. of absorption area per bedroom. Therefore the no. of bedrooms x j3U sq. ft. minimum requirement = a total of >sq. ft. of absorption area. May we suggest ,. eX dr , .ix .3 0/ ,5 g-x..31 t3 Date a 3 Inspector r+ -4 2 d FINAL APPROVAL OF SYSTEM: No system shall be deemed to be in compliance with the Sewage Disposal Laws until the assembled system is approved prior to cover- ing any part. Septic Tank access for inspection and cleaning within 12" of ground surface or aerated access ports above ground surface. Proper materials and assembly. FT,AA O name of septic tank or aerated treatment unit. Adequate absorption (or dispersal) area. ca---"1/ 3 /S779 -Gt 2s nom Adequate compliance with permit requirements. e Adequate compliance with County and State regulations /requirements. Other Date 9 ` Inspector RETAIN WITH RECEIPT RECORDS AT CONSTRUCTION SITE CONDITIONS: 1. All installation must comply with all requirements of the County Individual Sewage Disposal Regulations, adopted pursuant to au- thority granted in 66 -44 -4, CRS 1963, amended 66-3-14, CRS 1963. 2. This permit is valid only for connection to structures which have fully, complied with County zoning and building requirements. Connection to or use with any dwelling or structures not approved by the Building and Zoning office shall automatically be a viola- tion of a requirement of the permit and cause for both legal action and revocation of the permit. 3. Section III, 3.24 requires any person who constructs, alters, or installs an individual sewage disposal system in a manner which in- volves a knowing and material variation from the terms or specifications contained in the application of permit commits a Class 1, Petty Offense ($500.00 fine — 6 months in jail or both). iflrip III u I ai 6 Building (*diet ~V 4rmlt White Copy AdPIlee'ht -+ Green Copy t DO*. *-.Pink Copy L.. Y....... g4L LJ ... ..4....[w11•YWW ^ lhli1u1 i k.AUILee... 1116L irC \u'ili .W4vIWk W^i:rrirJ!'i n `VWdiYWl a 4i Lrr.rr.:"r,..r.1rr+sa..AiiiLJ it . Fees Paid $'7 S Gc) INDIVIDUAL SEWAGE DISPOSAL SYSTEMS APPLICATION Date/7- 2'g0 `- NOTIFICATION OF PROPOSED DISCHARGE TO WATERS OF THE STATE INDIVIDUAL HOME SEWAGE TREATMENT SYSTEM Owner:c1 intew 7k f_ . r y o /City:cgc. X1 7 Mail Address:y:l Zip: 'i' /F s/ Phone: 3y.2 INFORMATION REGARDING PROJECT SUBMITTED FOR REVIEW Attach separate sheets or report showing entire area with respect to surrounding areas, topography of area, habitable buildings, location of potable water wells, soil percola- tion test holes, soil profiles in test holes. 1. Location of facility: County Garfield City or Town 17/`1 Legal Description 4t Ad e .Lot S'0 cores , 2. 1 c_ 2. No. of Bedrooms Septic Tank / Capac I- 5 (- tr ie -,. Unit Capacity 3. Source of Domestic Water: Public (name): 6 ea Zot S 57e-c.c.„---/ Private: Well Depth Other Depth to first ground water table 4. Is facility within boundaries of a city /town or sanitation district? 4f( 5. Distance to nearest sewer system:T ore 6 Have you attempted to arrange a connection with the system?62 If rejected, what was the reason? 6. Rate of absorption in test holes shown on the location map, in min'tes per inch of drop in water level after holes have been soaked for 24 .hours: J_.' 1 ," 7. Name, address, and telephone of person who made soil absorption t ts: 8. Name, address, and telephone of person responsible for design of the system: 9. Express permission is hereby granted for the inspection of the above property by any member of the Garfield County Environmental Health Department and /or such persons as they may designate. Any withdrawal of this permission shall be in writing and receipt acknowledged by the County Environmental Health Department. 10. I have been given an opportunity to read the Individual Disposal Systems Regulations of Garfield County and I hereby agree to comply with all terms, conditions and requirements included therein. t -7( Date gnature of Ap cant TO BE RETURNED TO HEALTH DEPT.) Gareld County, CO Developed by Account Number  R023067 Parcel Number  217914300001 Acres 10 Land SqFt 0 Tax Area 023 Mill Levy 70.1900 Physical Address  1430 MINEOTA DR   SILT 81652 Owner Address  SUTHERLAND, SCOTT R & HEIDI L 1430 MINEOTA DR SILT CO 81652-9577 Total Actual Value  $0 Last 2 Sales Date  Price   4/28/2000  $220,000   9/28/1992  $88,000   Date created: 5/15/2025 Last Data Uploaded: 5/15/2025 7:11:38 AM 912 ft Overview Legend Parcels Roads Parcel/Account Numbers Owner Name Lakes & Rivers County Boundary Line