Loading...
HomeMy WebLinkAboutEngineer's OWTS Design Plan-Revised129 Cains Lane Carbondale, CO 81623 970.309.5259 carla.ostberg@gmail.com August 21, 2024 Project No. C1908 Cain Cooklin cain.cooklin@hotmail.com Subsurface Investigation and Onsite Wastewater Treatment System Design 2-Bedroom Residence 6773 Four Mile Road Garfield County, Colorado Cain , CBO Inc. performed a subsurface investigation and completed an onsite wastewater treatment system (OWTS) design for the subject residence. The 1.919 -acre property is located outside of Glenwood Springs, in an area where OWTSs and wells are necessary. Legal Description: Section: 22 Township: 7 Range: 89 TR IN LOT 2 Parcel ID: 2395-221-00-002 SITE CONDITIONS The property is currently developed with a 2-bedroom residence. The existing OWTS serving the residence consists of a 1000-gallon, two -compartment concrete septic tank followed by a series of pipe and gravel areas that varied in direction and location. The outlet side of the septic tank appears to be in poor condition around the outlet pipe although the septic tank was water-tight prior to pumping. The portion of the soil treatment area (STA) near the eastern property boundary is saturated. Jetting and camera work was done to establish the location of STA and multiple laterals were discovered, including a solid pipe from the septic tank to a lateral leading towards the creek. We believe a portion of the STA encroached on the 50-foot setback to the creek. With no reasonable way to repair the system, this design will replace the existing OWTS. The residence is served by a private well on the property. The well is located to the west of Four Mile Creek. The well is located greater than 50-feet from the proposed septic tank and greater than 100-feet from the proposed STA. Four Mile Creek bisects the property. We believe the existing STA encroaches on the minimum 50-foot setback to the Creek. The proposed STA will likely be outside of the 50-feet setback; however, if a slight encroachment is necessary, it will not come closer than the existing STA1. The proposed soil treatment area (STA) location is relatively flat and is in a non-irrigated yard area. 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. 1 Garfield County OWTS Regulation 43.7 Table 7-1 Note: For repair or upgrading of existing OWTS where the size of lot precludes adherence to these distances, a repaired OWTS must not be closer to setback features than the existing OWTS, as reviewed and approved by the local public health agency. Page 2 Outlet side of septic tank Existing septic tank has a mid-steam Trouble-shooting by running water through outlet pipe SUBSURFACE The subsurface was investigated on August 12, 2024 by digging one soil profile test pit excavations (Test Pits). A visual and tactile soil analysis was completed by Carla Ostberg at the time of excavation.2 Only one test pit was excavated due to space constraints. The materials encountered in Test Pit #1 consisted of dark brown loamy topsoil to 18-inches, underlain by light to medium brown sandy loam with a reddish brown silt loam to silt clay loam horizon at 4.5 to 5.0- feet where a solid distribution pipe was discovered. We ran water from the septic tank and found the water flowed through the distribution pipe. The reddish brown soil was evident only around the pipe and we assume this soil was imported for the purpose of bedding the pipe. The Test Pit was further excavated to a maximum depth explored of 8.0 -feet with light to medium brown silt loam below the pipe. No bedrock or groundwater was encountered. A sample of the soil was taken from Test Pit #1 at 4-feet below grade. Soil structure grade was moderate. The soil formed a ball and a ribbon approximately 1-inch in length before breaking. Soil structure shape was blocky and consistence was friable. Soil texture was more gritty than smooth. 2 Carla Ostberg holds a Certificate of Attendance and Examination from the CPOW Visual and Tactile Evaluation of Soils Training. Page 3 The soil is consistent with Soil Type 2, Sandy Loam, with moderate structure grade. A long-term acceptance rate (LTAR) of 0.6 gallons per square foot will be used to design the STA. Full depth of Test Pit #1 Solid distribution pipe at 4.5 to 5-feet Page 4 Beginning excavation of Test Pit #1 Topsoil Test Pit Reddish brown soils encountered Page 5 Reddish brown soils are Silty Clay Loam (we believe imported to bed the pipe) Page 6 Sample included some reddish brown soils Ribbon approx. 1-inch in length Pipe discovered Page 7 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 2 Bedrooms = 300 GPD LTAR = 0.6 GPD/SF 300 GPD / 0.6 GPD/SF = 500 SF x 1.2 (gravity, bed) x 0.7 (GeoMat™ with min. 6” sand) = 420 SF The OWTS design is based on 2-bedrooms. An average daily wastewater flow of 300 GPD will be used. For the purposes of this OWTS design, Benchmark Elevation has been established as 100’ (Elevation of existing sewer line). 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 15’ / min. 2% fall / min. 3.75” fall Distribution Box (OPTIONAL) Approximate horizontal distance 7’ / min. 1% fall / min. 0.875” fall Infiltrative Surface Approximate horizontal distance 5’ / min. 1% fall to STA / min. 0.625” 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. Any portion of the sewer pipe from the house found to be in poor condition should be replaced. A new, 4- inch SDR-35 sewer line will be installed with a double -sweep clean out and a minimum 2% grade to the new septic tank. The system installation must include a 1000-gallon, two-compartment Infiltrator® poly septic tank with an Orenco® Biotube effluent filter on the outlet tee. Any state-approved concrete or poly septic tank 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. Page 8 Effluent will gravity flow to a distribution box, and then a GeoMat™ bed with four perforated laterals. 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 row. Installation of a distribution box is OPTIONAL and may be replaced with a level manifold connecting the laterals. Effluent will gravity flow to a 13’ x 32.5’ bed with a minimum of 6-inches of sand under 39” wide sheets 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. Laterals must be perforated 4-inch diameter pipe on the center of feet on center of each 39” wide GeoMat™ sheet. Four 39” wide GeoMat™ sheets must be placed on the 13-foot wide bed. The gray GeoMat™ separation fabric 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 in the corners of the front of each bed and at the ends 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 Infiltrator® IM-1060-2CP 1000-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 (4) GeoMat™ Geomatrix Systems, LLC 39” wide 130 lineal feet GeoMat™ Construction must be according to the jurisdiction’s adopted On-Site Wastewater Treatment System Regulations, the OWTS Permit, and this design. Page 9 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 10 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 6773 CR 117 Legend 100 Club Colorado 6773 Co Rd 117 100 ft N ➤➤ N T C SS EM C o u n t y R o a d 1 1 7 6773 County Road #117 2.00 acres ± Site - VICINITY MAP - Not to Scale - LEGEND - T S C EM Approved: Title: Improvement Location Certificate Re v i s i o n # Sheet No. 67 7 3 C o u n t y R o a d 1 1 7 Gl e n w o o d S p r i n g s , C o l o r a d o Job No. Drawn by: Date: File: 6773CR117 FB 8/15/2024 FB 6773CR117 11 8 W e s t S i x t h S t r e e t , S u i t e 2 0 0 Gl e n w o o d S p r i n g s , C O 8 1 6 0 1 97 0 . 9 4 5 . 1 0 0 4 ww w . s g m - i n c . c o m Da t e By : 1 1Of : ..PLS: Graphic Scale In U.S. Feet : 1" = 20' 0 10 20 40 Improvement Location Certificate 6773 County Road 117 A parcel of land situated in Section 22, Township 7 South, Range 89 West of the 6th P.M. Garfield County, Colorado Richard Fox Benton Colorado PLS # 38792 Gareld County, CO Developed by Account Number   R080063 Parcel Number  239522100002 Acres 2 Land SqFt 0 Tax Area 131 Mill Levy 73.2960 Physical Address   6773 117 COUNTY RD   GLENWOOD SPRINGS 81601 Owner Address  COOKLIN, CAIN 6773 COUNTY RAOD 117 GLENWOOD SPRINGS CO 81601 Total Actual Value   $566,690 Last 2 Sales Date  Price   10/24/2012  $211,000   11/9/2011  $335,601   Date created: 8/25/2024 Last Data Uploaded: 8/24/2024 10:32:45 PM 230 ft Overview Legend Parcels Roads Parcel/Account Numbers Owner Name Lakes & Rivers County Boundary Line • Has 5-10 times more flow area than other brands, so lasts many times longer between clean- ings, increasing homeowner satisfaction • Installs in min- utes inside new or existing tanks; extendible tee handle for easy removal • Easy to clean by simply hosing off whenever the tank needs pumping • Removes about two-thirds of sus- pended solids, on average, extending drainfield life • Corrosion-proof construction, to ensure long life • Lifetime warranty Residential Biotube® Effluent Filters Applications Our patented* 4-in. (100-mm) Biotube Effluent Filters, Biotube Jr., Biotube Insert Filters, and Biotube Base Inlet Filters are ideal for residential septic tanks and have a lifetime warranty. They prevent large solids from leaving the tank, dramatically improving wastewater quality and extending the life of residential drainfields. Standard Features & Benefits • Alarm available, to signal the need for cleaning • Flow modulating discharge orifices available to limit flow rate leaving tank, mitigat- ing surges and increasing retention time • Custom and commercial sizes available Effluent from the relatively clear zone of the septic tank, between the scum and sludge layers, horizontally enters the Biotube Effluent Filter. Effluent then enters the annular space between the housing and the Biotubes, utilizing the Biotubes’ entire surface for filtering. Particles larger than the Biotube’s mesh are prevented from leaving the tank. Optional Features & Benefits Biotube Filtering Process 8-in. (200-mm) Base Inlet Filter 4-in. (100-mm) Insert Filter 4-in. (100-mm) Biotube Jr. (4-in. Biotube cartridge avail- able separately as Insert Filter) Orenco’s superior effluent filters resist clogging better than all other brands. Our stan- dard, full-sized 4-in. (100-mm) Biotube Effluent Filter provides maximum long-term protection in a complete package, with housing. Our 4-in. (100-mm) Biotube Jr., at half the size of our standard model, has more filtering capacity than the full-sized filters sold by other manufacturers. For tanks with existing outlet tees, the Biotube Insert Filter is ideal. And for low-profile tanks, there’s the Base Inlet Filter. * Covered by patent numbers 5,492,635 and 4,439,323 4-in. (100-mm) Biotube Effluent Filter APS-FT-1 Rev. 3.4 © 11/10 Orenco Systems®, Inc. To Order Call your nearest Orenco Systems®, Inc. distributor. For nearest distribu- tor, call Orenco at 800-348-9843 or go to www.orenco.com and click on “Distributor Locator.” Nomenclatures Riser wall Tank wall Filter housing Extendible PVC handle Stainless steel set screws Top seal plate Air vents Biotube® filter cartridge Solid base 4-in. Biotube Effluent Filter 4-in. Biotube Jr. 4-in. Biotube Filter (standard) 4-in. Biotube Jr. (includes cartridge and housing) Distributed By: 8-in. Biotube Filter (base inlet model) 4-in. Biotube Filter Insert (cartridge only) Junior series FT J0418 Biotube effluent filter series Filter diameter (inches) Cartridge height (inches) W = fits Type 3034 outlet tee S = fits Schedule 40 outlet tee Options: Blank = no options M = flow modulation plate installed A = float bracket attached Blank = 1/8" filtration P = 1/16" filtration Insert FT i0418 Biotube effluent filter series Filter diameter (inches) Cartridge height (inches) W = fits Type 3034 outlet tee S = fits Schedule 40 outlet tee - For customized options (e.g., NC indicates North Carolina regions) - Blank = 1/8" filtration P = 1/16" filtration FT 04 Biotube effluent filter series Filter diameter (inches) Housing height: 36" and 44" are standard Options: Blank = no options M = flow modulation plate installed A = float bracket attached Cartridge height: 28" and 36" are standard - Blank = 1/8" filtration P = 1/16" filtration W = fits Type 3034 outlet pipe S = fits Schedule 40 outlet pipe FT 2208 14 B Biotube effluent filter series Housing height: 22" standard Cartridge height: 14" standard Options: A = float bracket FS = 2" outlet orifice FSO = 2" outlet orifice and overflow plate* Base inlet model - Blank = 1/8" filtration P = 1/16" filtration Filter diameter (inches) 08 = 8" * Also available with coupling and sleeve as a “kit”: FT-OVERFLOWKIT