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Home My WebLink AboutOWTS Design-Revised 11.06.24129 Cains Lane Carbondale, CO 81623 970.309.5259 carla.ostberg@gmail.com November 6, 2024 Project No. C1920 Ryan Williams 929willy@gmail.com Subsurface Investigation and Onsite Wastewater Treatment System Design 2-Bedroom Residence + Future 4-Bedroom Residence TBD Panorama Drive Garfield County, Colorado Ryan, CBO Inc. performed a subsurface investigation and completed an onsite wastewater treatment system (OWTS) design for the subject residence. The 5.09-acre property is located outside of Carbondale, in an area where OWTSs and wells are necessary. Legal Description: Section: 17 Township: 7 Range: 87 TR IN N1/2NW 5.09 ACRES Parcel ID: 2391-172-00-130 SITE CONDITIONS The property is currently undeveloped. A 2-bedroom residence is proposed. A future 4-bedroom residence is also contemplated. The residences will be served by a shared well located on the adjacent property to west. The well is approximately 750-feet northwest of the proposed residence. The water line will not come within 25-feet of any OWTS component. The proposed soil treatment area (STA) location has an approximate fifteen percent slope to the east. The proposed area is vegetated with sage, native grasses, and scrub oak. 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 October 18, 2024 by digging three 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 dark brown clay loam topsoil to 1-foot, underlain by tan to whitish calcareous clay matrix with sporadic large basalt boulders to a maximum depth explored of 6.0-feet. No bedrock or groundwater was encountered. 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 #2 consisted of dark brown clay loam topsoil to 18 -inches, underlain by tan to whitish calcareous clay matrix to a maximum depth explored of 4.0-feet where practical digging refusal on a large boulder was encountered. No bedrock or groundwater was encountered. The materials encountered in Test Pit #3 consisted of dark brown clay loam topsoil to 1-foot, underlain by tan to whitish calcareous clay matrix with scattered cobbles and large basalt boulders to a maximum depth explored of 4.0 -feet. Encountering similar soil conditions as pervious test pits, we opted to discontinue digging. 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 moderate. The soil formed a ball and a ribbon less than 1-inch in length before breaking. Soil structure shape was blocky and consistence was friable to firm. Soil texture was both gritty and smooth. We have researched soils in the area through USGS Web Soil Survey. The report is enclosed. The area of the proposed STA is identified by map unit symbol 87. The map unit name is Morval-Tridell complex, 12 to 50% slopes. The calcareous clay matrix horizon is consistent with Soil Type 2 with moderate structure grade. While large basalt boulders were encountered, they are sporadic. A long-term acceptance rate (LTAR) of 0.6 gallons per square foot will be used to design the STA. Approx. STA Test Pit #1 Page 3 Sieved sample Ribbon approx. 1-inch in length Backfill Test Pit #1 Looking from Test Pit #1 towards Test Pit #2 Page 4 Peds Backfill Test Pit #2 Test Pit #2 Test Pit #3 Page 5 DESIGN SPECIFICATIONS Design Calculations: 2-Bedroom Residence = 75 GPD x 2 people/bedroom x 2 Bedrooms = 300 GPD Future 4-Bedroom Residence = 75 GPD x 2 people/bedroom x 3 Bedrooms + 75 GPD (4th bedroom) = 525 GPD Average Design Flow = 300 GPD + 525 GPD = 825 GPD LTAR = 0.6 GPD/SF 825 GPD / 0.6 GPD/SF = 1375 SF x 1.0 (gravity, trenches) x 0.7 (GeoMat™ with min. 6” sand filter material) = min. 962.5 SF The OWTS design is based on a 2-bedroom residence and a future 4 -bedroom residence . An average daily wastewater flow of 825 GPD will be used. For the purposes of this OWTS design, Benchmark Elevation at grade 7217 ’ has been established as 100’ (Finished Floor of the 2-bedroom 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 99’ / min. 2% fall / min. 24.75” fall Distribution Box Approximate horizontal distance 9’ / min. 1% fall / min. 1.125” fall Infiltrative Surface Approximate horizontal distance 30’ to furthest trench / min. 1% fall to STA / min. 3.75” 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. Where the sewer line crosses the driveway, it must be minimum Schedule 40. If desired, it may be placed in a larger diameter minimum Schedule 40 conduit. If the sewer line run extends further than 100-feet, an additional clean out must be installed. The system installation must include a 2000-gallon, two-compartment Valley Precast concrete 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 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 be 3’ x 54’ trenches with a minimum of 6-inches of sand filter material under a 39” wide sheet of GeoMat™. 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 0.15 and 0.60 mm. The uniformity coefficient must be 7.0 or less. Material meeting ASTM 33, for concrete sand, with three percent or less fines passing 200 mesh sieve may be used. A gradation of the sand media must be submitted to this office prior to obtaining the sand. The six total trenches will total 324 lineal feet of GeoMat™ and 972 square feet of infiltrative area. There must be at least 4-feet of undisturbed soil between each trench. Laterals must be perforated 4-inch diameter pipe set down the center of each 39” wide GeoMat™ sheet. The gray GeoMat™ separation fabric Page 6 will cover the laterals. All material associated with the GeoMat™ installation must be proprietary products associated with the GeoMat™. Manufacturer instructions must be followed regarding installation of the GeoMat™. Inspection ports must be installed at the beginning and end of each trench, into the sand filter material. Clean outs (inspection ports) must also be installed at the end of each perforated lateral. 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 Valley Precast Item 2000T-2CP 2000-gallon, two- compartment concrete 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 Min. 6 outlet Distribution box, risers, lid, flow equalizers (6) GeoMat™ Geomatrix Systems, LLC 39” wide 324 lineal feet GeoMat™ 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 Page 7 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. 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. Page 8 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 4,514 752.3 Map Viewer This product is for informational purposes and may not have been prepared for, or be suitable for legal, engineering, or surveying purposes. Users of this information should review or consult the primary data and information sources to ascertain the usability of the information. 3,5081: Feet5850 Legend 292 Notes Location 585 Date Prepared: 11/16/2024 2:17:02 PM Well Constructed Final Permit Ground Water Geophysical Log County Superfund Sites Aspen-Gypsum Area, Colorado, Parts of Eagle, Garfield, and Pitkin Counties 87—Morval-Tridell complex, 12 to 50 percent slopes Map Unit Setting National map unit symbol: jq7k Elevation: 6,800 to 8,000 feet Mean annual precipitation: 14 to 16 inches Mean annual air temperature: 42 to 44 degrees F Frost-free period: 85 to 95 days Farmland classification: Not prime farmland Map Unit Composition Morval and similar soils:55 percent Tridell and similar soils:30 percent Minor components:15 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Morval Setting Landform:Alluvial fans Down-slope shape:Linear Across-slope shape:Linear Parent material:Alluvium derived from sandstone and shale and/or colluvium derived from sandstone and shale Typical profile H1 - 0 to 7 inches: loam H2 - 7 to 19 inches: clay loam H3 - 19 to 60 inches: loam Properties and qualities Slope:12 to 40 percent Depth to restrictive feature:More than 80 inches Drainage class:Well drained Runoff class: Very high Capacity of the most limiting layer to transmit water (Ksat):Moderately high (0.20 to 0.60 in/hr) Depth to water table:More than 80 inches Frequency of flooding:None Frequency of ponding:None Calcium carbonate, maximum content:25 percent Maximum salinity:Nonsaline to slightly saline (0.0 to 4.0 mmhos/cm) Available water supply, 0 to 60 inches: High (about 9.3 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 7e Map Unit Description: Morval-Tridell complex, 12 to 50 percent slopes---Aspen-Gypsum Area, Colorado, Parts of Eagle, Garfield, and Pitkin Counties Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 11/6/2024 Page 1 of 3 Hydrologic Soil Group: C Ecological site: R048AY292CO - Deep Loam Other vegetative classification: DEEP LOAM (null_11) Hydric soil rating: No Description of Tridell Setting Landform:Mountains Landform position (three-dimensional):Mountainbase Down-slope shape:Linear Across-slope shape:Linear Parent material:Alluvium derived from basalt and/or colluvium derived from basalt Typical profile H1 - 0 to 2 inches: stony sandy loam H2 - 2 to 14 inches: very cobbly fine sandy loam H3 - 14 to 25 inches: cobbly sandy loam H4 - 25 to 37 inches: very stony fine sandy loam H5 - 37 to 60 inches: very stony loamy sand Properties and qualities Slope:12 to 50 percent Depth to restrictive feature:More than 80 inches Drainage class:Well drained Runoff class: Medium Capacity of the most limiting layer to transmit water (Ksat):Moderately high to high (0.60 to 6.00 in/hr) Depth to water table:More than 80 inches Frequency of flooding:None Frequency of ponding:None Calcium carbonate, maximum content:25 percent Maximum salinity:Nonsaline to very slightly saline (0.0 to 2.0 mmhos/cm) Available water supply, 0 to 60 inches: Low (about 4.0 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 7s Hydrologic Soil Group: A Ecological site: R048AY287CO - Stony Foothills Other vegetative classification: PINYON-JUNIPER (null_53) Hydric soil rating: No Minor Components Other soils Percent of map unit:15 percent Map Unit Description: Morval-Tridell complex, 12 to 50 percent slopes---Aspen-Gypsum Area, Colorado, Parts of Eagle, Garfield, and Pitkin Counties Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 11/6/2024 Page 2 of 3 Hydric soil rating: No Data Source Information Soil Survey Area: Aspen-Gypsum Area, Colorado, Parts of Eagle, Garfield, and Pitkin Counties Survey Area Data: Version 15, Aug 29, 2024 Map Unit Description: Morval-Tridell complex, 12 to 50 percent slopes---Aspen-Gypsum Area, Colorado, Parts of Eagle, Garfield, and Pitkin Counties Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 11/6/2024 Page 3 of 3 Soil Map—Aspen-Gypsum Area, Colorado, Parts of Eagle, Garfield, and Pitkin Counties Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 11/6/2024 Page 1 of 3 43 6 9 1 2 0 43 6 9 1 5 0 43 6 9 1 8 0 43 6 9 2 1 0 43 6 9 2 4 0 43 6 9 2 7 0 43 6 9 3 0 0 43 6 9 1 2 0 43 6 9 1 5 0 43 6 9 1 8 0 43 6 9 2 1 0 43 6 9 2 4 0 43 6 9 2 7 0 43 6 9 3 0 0 316040 316070 316100 316130 316160 316190 316220 316250 316280 316310 316340 316040 316070 316100 316130 316160 316190 316220 316250 316280 316310 39° 27' 13'' N 10 7 ° 8 ' 1 7 ' ' W 39° 27' 13'' N 10 7 ° 8 ' 4 ' ' W 39° 27' 6'' N 10 7 ° 8 ' 1 7 ' ' W 39° 27' 6'' N 10 7 ° 8 ' 4 ' ' W N Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84 0 50 100 200 300 Feet 0 20 40 80 120 Meters Map Scale: 1:1,380 if printed on A landscape (11" x 8.5") sheet. Soil Map may not be valid at this scale. MAP LEGEND MAP INFORMATION Area of Interest (AOI) Area of Interest (AOI) Soils Soil Map Unit Polygons Soil Map Unit Lines Soil Map Unit Points Special Point Features Blowout Borrow Pit Clay Spot Closed Depression Gravel Pit Gravelly Spot Landfill Lava Flow Marsh or swamp Mine or Quarry Miscellaneous Water Perennial Water Rock Outcrop Saline Spot Sandy Spot Severely Eroded Spot Sinkhole Slide or Slip Sodic Spot Spoil Area Stony Spot Very Stony Spot Wet Spot Other Special Line Features Water Features Streams and Canals Transportation Rails Interstate Highways US Routes Major Roads Local Roads Background Aerial Photography The soil surveys that comprise your AOI were mapped at 1:24,000. Warning: Soil Map may not be valid at this scale. Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale. Please rely on the bar scale on each map sheet for map measurements. Source of Map: Natural Resources Conservation Service Web Soil Survey URL: Coordinate System: Web Mercator (EPSG:3857) Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required. This product is generated from the USDA-NRCS certified data as of the version date(s) listed below. Soil Survey Area: Aspen-Gypsum Area, Colorado, Parts of Eagle, Garfield, and Pitkin Counties Survey Area Data: Version 15, Aug 29, 2024 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Aug 25, 2021—Sep 5, 2021 The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident. Soil Map—Aspen-Gypsum Area, Colorado, Parts of Eagle, Garfield, and Pitkin Counties Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 11/6/2024 Page 2 of 3 Map Unit Legend Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI 87 Morval-Tridell complex, 12 to 50 percent slopes 7.6 100.0% Totals for Area of Interest 7.6 100.0% Soil Map—Aspen-Gypsum Area, Colorado, Parts of Eagle, Garfield, and Pitkin Counties Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 11/6/2024 Page 3 of 3 Gareld County, CO Developed by Account Number R111408 Parcel Number 239117200130 Acres 5 Land SqFt 0 Tax Area 011 Mill Levy 72.5180 Physical Address 0 CARBONDALE 81623 Owner Address WILLIAMS, JON RYAN 267 RABBIT ROAD CARBONDALE CO 81623 Total Actual Value $450,000 Last 2 Sales Date Price 10/12/2023 $485,000 7/16/1999 $0 Date created: 11/6/2024 Last Data Uploaded: 11/6/2024 2:12:08 AM 921 ft Overview Legend Parcels Roads Parcel/Account Numbers Owner Name Lakes & Rivers County Boundary Line