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Home My WebLink AboutSubsurface Investigation & OWTS Design ModificationApril 2, 2015 CBO Inc. 33 Four Wheel Drive Road Carbondale, CO 81623 cell) 970-309-5259 office) 970-704-0484 carla .ostberg@gmail.com Tommy Junge tommyjunge@yahoo .com Project No. C1134 Subsurface Investigation and Onsite Wastewater Treatment System (OWTS) Design Modification 3-Bedroom Residence 688 CR 250 Garfield County, Colorado Tommy, CBO Inc. performed a subsurface investigation and onsite wastewater treatment system (OWTS) design modification for the subject property. The property is located outside of Silt, in an area where OWTSs and wells are necessary. Legal Description: Section: 36 Township: 5 Range: 92 Lot 3, Simon Exemption The existing OWTS serving the residence is still functioning, but there is a desire to add additional capacity to the soil treatment area (ST A). Records from Garfield County were obtained and Permit 3205 documents this OWTS. There is an existing 1000-gallon concrete septic tank and a 16' x 64' sand filter bed with 3 rows of 9 Standard Infiltrator® chambers. The design document notes a minimum of 4-feet of sand filter material was placed in the over-excavation . The system was sized to accommodate 3- bedrooms. SITE CONDITIONS A 3-bedroom, single-family residence presently exists and is utilizing an existing OWTS. An addition to the STA is being proposed. The existing STA will remain and will be utilized as an alternating system. The area of the proposed STA is located south of the existing ST A. It is in an irrigated yard , and slopes slightly to the south over the proposed STA. We recommend minimizing irrigation over the STA. The residence is served by a private well, located greater than 100-feet from the proposed STA. There is no contemplated increase in bedroom count for the residence. SUBSURFACE The subsurface was investigated on March 31 , 2015 by digging one soil profile test pit excavation (Test Pit). A visual and tactile analysis of the soil was completed by Carla Ostberg at the time of excavation.1 1 Carla Ostberg holds a Certificate of Attendance and Examination from the CPOWVisual and Tactile Evaluation of Soils Training. Page 2 The materials encountered in the Test Pit #1 consisted of dark brown topsoil to 18-inches, underlain by dark brown, firm, moist, clay with a layer of 2 to 4-inch diameter cobbles to 30-inches, underlain by dark brown , firm, moist clay to maximum depth explored of 7.0-feet. The soils have a granular structure shape, a strong structure grade, and friable consistence. A sample of clay soils formed a ball and ribbon greater than 2-inches in length before breaking. The soil felt both gritty and smooth . Soils encountered below 6-feet were wet (muddy). For purposes of this design, groundwater is estimated at approximately 6-feet below grade. STA sizing is based on Soil Type 4, Clay A long term acceptance rate (L TAR) of 0.2 gallons per square foot will be used to design the OWTS, in accordance with Table 10-1 Soil Type 2A presented in the Garfield County On-Site Wastewater Treatment System Regulations, effective June 30. 2014. Test Pit observed March 31, 2015 Test Pit#1 DESIGN SPECIFICATIONS Cobble lay er EJ The existing 1000-gallon, two-compartment septic tank will remain and an effluent filter added to the outlet tee . The existing distribution box and existing sand filter STA will remain in use . Additional square footage will be added to the ST A and the ST As will alternate. The new STA design is based on 3-bedrooms, with 50% of the total required area for an alternating STA. An average daily wastewater flow of 450 GPO will be used. Design Calculations: 3 bedrooms x 75 GPO/person x 2 people/bedroom = 450 GPO 1 ~D 450 GPO I 0.2 gal/SF = 2250 square feet 2250 SF x 1.0 (gravity trenches) x 0. 7 (chambers) = 1575 SF / 2 = 7•SF 788 SF / 12 SF/chamber= min. 66 'Quick 4' Infiltrator® chambers :Z. Page3 The existing distribution box, which is already accessible from grade, will be modified to either cap one outlet pipe annually to allow alternation of ST As, or ball valves can be placed on the sewer pipes existing the distribution box to allow one field to be Qturned off' annually. We recommend removing any debris and sludge from the existing distribution box and jetting the line from the distribution box to the existing STA. Jetting of this line will clear debris from the pipe and allow proper location of the manifold connecting the three existing rows of Standard Infiltrators®. Once located, an inspection port can be installed at the beginning of the bed for future monitoring. A new distribution box, accessible from grade, will be installed after the existing distribution box. The new distribution box will have three outlets, one to each new trench. Three rows of 22 'Quick 4' Infiltrator® chambers must be installed to the south of the existing ST A. If three rows are too long, an option is to insta/14 rows of 17 'Quick 4 ' Infiltrator® chambers. The existing grasses and vegetation must be scraped and soils scarified for the Infiltrator® chambers to be placed just below existing grade to allow a sufficient (minimum 4-feet) separation between the infiltrative area and groundwater. There must be a minimum of 6-feet of undisturbed soil between each trench. Inspection ports must be placed at the beginning and end of each trench. Backfill over the STA must be uniform and granular with no material greater than minus 3-inch. Inlet tee Exist ing septic tank under concrete pad and smokers -accessible through cuts in concrete Outlet tee (must add effluent filter) Page4 jl .. l Some deterioration of concrete around outlet tee Existing distribution box The existing STA must rest for a minimum of 1 year before altemating. With any alternating system . the property owner is responsible for switching the alternating STAs on an annual basis and keeping records which document the alternating cycles. 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 . REVEGETATION REQUIREMENTS An adequate layer of good quality topsoil capable of supporting revegetation shall be placed over the entire disturbed are 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 irritation shall be plated over the area. 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 absorption systems , and any other components needing maintenance. Geo-fabrics or plastics should not be used over the absorption area. No heavy equipment, machinery, or materials should be placed on backfilled absorption area. Livestock should not graze on the absorption area. 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 ST A. 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. Load ing 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. Page S ADDITIONAL CONSTRUCTION NOTES If design includes a pump, air release valves and weep holes must be installed to allow pump lines to drain to minimize risk of freezing . 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. 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. 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, Ctt.ti {l1 Os-f ht-~ 8 Carla Ostberg, MPH , REHS t~1shn3 sm l lci 1 x0~· ll Gl l\. c lA.u v...b r-:; _( G l l Residential Biotube® Effluent Filters Applications Our patented* 4·in. (IOO·mm) Biotube Effiuenc Filters, Biocube Jr., Biocube Insert Filters, and Biotubc Base lnlec Filters arc ideal for rcsidencial septic ranks and have a lifetime warranty. They prevenc large solids from leaving the tank, dramatically improving wastewater quality and extending the life of residential drainficlds. 4·in. (1 OO·mm) !Jiowbe Ejjl11ent Filter ( ~-· 4·in. (JOO-mm) Biotube Jr. (4-i11. BioN1be cartridge avai/- 11ble separately as Insert Filter) 8-in. (200-mm) Base Inlet Filter l 4-in. (JOO-mm) Insert Filter Orenco's superior ef]luent filters resist cloggi11g better than all other brands. 011r stan- dard, full-sized 4-in. (I 00-mm) Biot11be Efjl11ellt Filter provides n11txim11m long-tem1 protection in a complete package, with housing. 011r 4-in. (JOO-mm) Biowbe Jr., at half the size of our sttmdard model, has more filtering capacity than the fit/I-sized filters sold by other man11facn1rers. For tanks with existing otlllet tees, the Biotube Insert Filter is ideal And for low-profile tanks, there's the Base Inlet Filter. • Coveted by patent nurnhcrs 5.492.('35 •n<i 4,~)'>32.~ To Order Call your nearest Orenco Systems®, Inc. distributor. For nearest distribu- tor, call Orenco at 800-348·9843 or go ro www.orcnco.com and click on "Distributor Locator," APS·FT·1 Rev. 3.4C>11/10 Oren co SvsJems•, Inc. Standard Features & Benefits • 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 Optional Features & Benefits • Alarm available, to signal the need for cleaning • Row modulating discharge orifices available to limit flow rate leaving tank, mitigat- ing surges and increasing retention time • Custom and commercial sizes available • 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 Biotube Filtering Process 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. Orenco Systems In corporated Cb.wgin.( tfJr 1r;1J' rfu \\'or/A /J~(J \t{wru·.urr www.orenco.com ------. ' Nomenclatures 4-in. Biotube Riter (sta nd ard) FT D Oo4 0 1 0 -D10[1] ~-00 ~- ... ra.v modula!Jon plate onstal1ed A !loot bracket anached Cartridge height 28" and 36" are standard ousing height 36' and 44" are standaJd Filter diame:er Onchcs) W lits Type 3034 outlet pipe S fits Schedule 40 outlet pipe Blank t 18' flllrallon P • 1116" titration Bio!lltle eHluent f.tter series 8-in . Biotu be Riter (base inlet model) FT Ooa 22-114 Bl~ A lloot brada)t FS 2· outlet onfice F. SO = 2· outlet 011fiee and CHertkm plate' Base 111let mode Cartridge height: 14" standard Housmg height 22' standard filter d1am~1er 11nches) 08 8' B!ank t /8" l.l!ra! <Jl P 1116" f11!rat1or B1otube effluent t Iler series • Also available With ooup!:ng and sleeve as a 'kit'; FT-OVERFLOWKIT 4-in . Biotube Jr. !in cl udes cartridge and housing) FTJ 000418 C] 1-y;oos: Blarik = no options Al = fkllY moc1Jla!ion plate tOStal1ed A = Hoot bracket attadled caruldge height (inches) Filter d:ametci (inches) W = fits Type 3034 outlet lee s • fits Schellttle 40 outlet tee Blank • 1 /B' filtration P t/16" f1ltratt011 Junior series Biotubc clfluent fir.er series 4-in. Biotube Filter Inse rt (cartridge only) FT i 0 0418-0 -i=J 11 ~rus!omizedoptlOllS(eg .• NC rocates N®l Carot;na regions) W = I.ls Type 3034 outlel tee S = fits Schedule 40 ootlet tee Camidge height (ioches) Filler d1ame1er (inches) Blank • 110· f11trat1on P " 1116" f1ltralion Insert Biotube effluent f111er series 4-in. Biotube Effluent Filter 4-in . Biotube Jr. t----Filter housing ---t 000 Discribuced By: