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HomeMy WebLinkAboutOWTS Design33 Four Wheel Drive Road Carbondale, CO 81623 970.309.5259 carla.ostberg@gmail.com December 17, 2019 Project No. C1483 Robbie Levin robbie@leafpeople.com Subsurface Investigation and Onsite Wastewater Treatment System Design 4-Bedroom Residence Lot 1, Ranch at Coulter Creek Garfield County, Colorado Robbie, CBO Inc. performed a subsurface investigation and completed an onsite wastewater treatment system (OWTS) design for the subject residence. The 9.637-acre property is located outside of Glenwood Springs, in an area where OWTSs are necessary. Legal Description: Section: 6 Township: 7 Range: 87 Subdivision: RANCH AT COULTER CREEK PUD Lot: 1 AS PER FIRST AMENDED FINAL PLAT RECEPTION NUMBER 889891 9.637 ACRES Parcel ID: 2391-06-301-001 SITE CONDITIONS The property is currently undeveloped. A 3-bedroom residence is proposed with the possibility of an additional bedroom in the future. The residence will be served by a community water system. No water line will come within 25-feet of any OWTS component. An inactive, historic ditch bisects the property from north to south. While the ditch is currently inactive, it will further be mitigated in order to properly abandon the ditch in a manner that will not allow flow in the future. An additional irrigation ditch runs through the property to the south and then to the east. This ditch will remain active and is located greater than 50-feet from any OWTS component. The proposed soil treatment area (STA) is located in the southeastern corner of the building envelope. The proposed area has an approximate 5% slope to the southeast. The proposed STA is covered 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. Page 2 SUBSURFACE The subsurface was investigated on November 5, 2019 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 the Test Pit #1 consisted of medium brown clayey topsoil to 2.5-feet, underlain by light brown silty clay loam to a maximum depth explored of 8.0-feet. No bedrock or groundwater was encountered. The materials encountered in the Test Pit #2 consisted of medium brown clayey topsoil to 2.5-feet, underlain by light brown silty clay loam to a maximum depth explored of 6.0-feet. No bedrock or groundwater was encountered. The materials encountered in the Test Pit #3 consisted of medium brown clayey topsoil to 2.5-feet, underlain by light brown silty clay loam to a maximum depth explored of 6.0-feet. No bedrock or groundwater was encountered. A tactile analysis of the soils was taken from Test Pit #2 at 3-feet below grade. 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 more smooth than gritty. A tactile analysis of the soils was taken from Test Pit #3 at 3-feet below grade. 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 more smooth than gritty. While we anticipated a calcareous sandy silty clay horizon that is typically more permeable than the overlaying clayey topsoil, the materials appears to be mixed. The resulting STA sizing is based on Soil Type 3, Silty Clay Loam. A long term acceptance rate (LTAR) of 0.35 gallons per square foot will be used to design the OWTS. Test Pit #1 1 Carla Ostberg holds a Certificate of Attendance and Examination from the CPOW Visual and Tactile Evaluation of Soils Training. Page 3 Test Pit #2 Page 4 Test Pit #3 Sieved sample Test Pit #2 Sieved sample Test Pit #3 Page 5 All test pits showed a mixture of DESIGN SPECIFICATIONS Design Calculations: Average Design Flow = 75 GPD x 2 people/bedroom x 3 Bedrooms + 75 GPD (4th Bedroom) = 525 GPD LTAR = 0.35 GPD/SF 525 GPD / 0.35 GPD/SF x 1.0 (gravity trenches) x 0.7 (chambers) = 1050 SF Page 6 The new 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 7332’ has been established as the sewer line existing the residence (100’). 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 Min. 98’ (7330’) Distribution Box Min. 94’ (7326’) Infiltrative Surface (upper most trench) Min. 93’ (7325’) The 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 1250-gallon, two-compartment concrete septic tank with an 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 bed. Each trench will consist of 15 ‘Quick 4’ Low Profile Infiltrator® chambers for a total of 1080 square feet of infiltrative area. There must be at least 4-feet of undisturbed soil between each trench, although we recommend at least 6-feet. 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. The component manufacturers are typical of applications used by contractors and engineers in this area. Alternatives may be considered or recommended by contacting our office. Construction must be according to Garfield County On-Site Wastewater Treatment System Regulations, the OWTS Permit provided by Garfield County Building Department, and this design. 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 befo re 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 7 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 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 8 Please call with questions. Sincerely, CBO Inc. Carla Ostberg, MPH, REHS • 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 NOT TO SCALE07/24/2013EMB1 of 1DFHINFILTRATOR SYSTEMS INC.4 Business Park Rd. Old Saybrook, CT 06475(800) 221-4436INFILTRATORŠsystems inc .QUICK4 PLUS STANDARDLOW PROFILE CHAMBERPRODUCT SPECIFICATION8"48"INFILTRATOR SYSTEMS INC.QUICK4 PLUS STANDARDLOW PROFILE CHAMBERPRODUCT SPECIFICATION(NOT TO SCALE)(EFFECTIVE LENGTH)TOP VIEW53"SIDE VIEWEND VIEW34"QUICK4 PLUS ALL-IN-ONE END CAPQUICK4 PLUS END CAP18"18"8"8"3.3" INVERT3.3" INVERT13.3" EFFECTIVE LENGTH*4.5" EFFECTIVE LENGTH*INSPECTION PORT6"*ALL VIEWS = INSTALLED LENGTHS10.4" EFFECTIVE LENGTH*