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Home My WebLink AboutSubsurface Investigation and OWTS Design October 16, 2014 Project No. C1100 Jeff Holub 4802 CR 113 Carbondale, CO 81623 Subsurface Investigation and Onsite Wastewater Treatment System Design 3-Bedroom Residence 4802 CR 113 Garfield County, Colorado Jeff, ALL SERVICE septic, LLC performed a subsurface investigation and completed an onsite wastewater treatment system (OWTS) design for the subject residence. The property is located outside of Carbondale, in an area where OW TSs and wells are necessary. SITE CONDITIONS A 3-bedroom, single-family residence presently exists and is utilizing an existing OWTS that is experiencing problems. There is a desire to replace the soil treatment area (STA). The STA is slow- draining, causing the septic tank to be over-full at times. While the existing STA is not surfacing, there is water in the inspection port. The residence is served by a private well located greater than 100-feet from the proposed STA. Cattle Creek runs to the south of the proposed STA and a 50-foot minimum setback will be maintained. County Road 113 and a steep hillside border the property to the north. A pond exists to the east of the proposed STA. The proposed STA will be located farther from the pond and creek than the existing STA. Table 7-1 of Garfield County On-Site Wastewater Treatment System Regulations notes, “For repair or upgrading of existing OWTS where the size of the lot precludes adherence to these distances, a repaired OWTS shall not be closer to setback features than the existing OWTS, as reviewed and approved by the local public health agency.” SUBSURFACE The subsurface was investigated on September 22, 2014 by digging two soil profile test pit excavations (Test Pits) and doing a visual and tactile evaluation of the soil. Test Pit #1 was dug approximately a week before the evaluation, allowing the groundwater in the Test Pit to stabilize. The test pit and percolation holes were dug in preparation for percolation tests to be conducted by Garfield County personnel. When groundwater was discovered, the percolation tests were not conducted. Test Pit #2 was dug at the time of the subsurface investigation. Test Pit #1 was located in close proximity to the existing STA. The materials encountered in Test Pit #1 consisted of dark brown, moist topsoil to 1-foot, underlain by medium brown, moist, loose, sandy loam. Groundwater was encountered and stabilized at approximately 4.0-feet below grade. The materials encountered in Test Pit #2 consisted of dark brown, moist topsoil with 4 to 6-inch diameter cobbles, underlain by medium brown, moist, loose, sandy loam with light gray mottles to a maximum depth explored of 6.0-feet. Groundwater was observed entering Test Pit #2 at approximately 5-feet Page 2 below grade, coming from the north side of the pit (uphill side). We believe groundwater may be perched below the steep hillside located to the north of the property and is flowing toward Cattle Creek, causing high groundwater conditions on the property. The proposed STA will be at native grade and slightly mounded. Visual and tactile analysis of the soils below the topsoil horizon classify this material as Soil Type 2, Sandy Loam. A long term acceptance rate (LTAR) of 0.6 gallons per square foot will be used to design the OWTS, in accordance with Table 10-1 Soil Type 2 presented in the Garfield County On-Site Wastewater Treatment System Regulations, adopted April 14, 2014. Test Pits observed September 22, 2014 Test Pit #1 Groundwater stabilized at 4.0-feet below grade Test Pit #2 Groundwater entering Pit at approximately 5-feet below grade Site Photos Pond to the east of existing and proposed STAs. Cattle Creek to the south Page 3 View of existing STA (looking east) Looking west DESIGN SPECIFICATIONS The existing 1000-gallon, two-compartment septic tank with effluent filter and conveyance pipe will remain in use. Septic tank Inlet tee Outlet tee with filter The new STA design is based on 3-bedrooms. An average daily wastewater flow of 450 GPD will be used. A new 4-inch diameter sewer pipe should run from the existing clean-out on the existing sewer line (located west of the pond) to a new distribution box, accessible from grade. The distribution box may be replaced with a level manifold, if desired. Effluent will gravity flow to a gravelless chamber bed with four rows of 14 ‘Quick 4’ Infiltrator® chambers. Four-inch diameter perforated pipe will be hung with zip ties from the undersides of the chambers the entire length of each row. Inspection ports will be placed at the beginning and ends of each row. These may be cut to grade and capped or covered with valve boxes. Native vegetation must be scraped from the STA and 6-inches of concrete sand placed to native grade. Chambers must be placed on top of the sand, at native grade, in order to maintain a 4-foot separation between the infiltrative area and high groundwater. A minimum of 1-foot of cover must be placed over the chambers. Grading must accommodate run-off from the county road to the north. Native vegetation must be planted over the STA. 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. pond Inspection port and clean out Page 4 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 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 backfilled STAs. 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. 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, 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 ALL SERVICE septic, LLC 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. ALL SERVICE septic, LLC 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, ALL SERVICE septic, LLC 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 5 Please call with questions. Sincerely, ALL SERVICE septic, LLC Reviewed By: Carla Ostberg, MPH, REHS Liability Clause: Under no circumstances whatsoever shall the liability of ALL SERVICE septic, LLC, in connection with any contract, directly or indirectly, exceed the total amount paid by the client to ALL SERVICE septic, LLC for the services and/or goods which are the subject of the contract in connection with which the liability arises. N ~ THE LOCATION OF EXISTl'IGAHD PRCPOeED IMPROISIEN18 atCWINAAE NDI' THE IE!ULTOF A l'RDPERTY!IRVEY. 11£ LDCATICNSAAE APPROlGW.TE. Ir IS T1£ HOME.CWMERB DUTY TO ENSU'IEAU. CON9TRUCTION AND IW'ROVEMB'flS LOCATIONS ARE M:Cl.IRAlE All. BET'llACIC DISTANCES BHCULD BE CDNFIRMBI PRJCR TO EXCAVATION. SCIH:1"•30'.Q' 61Rl!U11CN llCIX. AC<DSIBLEATGRADE 4" DIA 9~ SEWiRUIEll TO CHAMIERS-----.. INSPECTlClN PClRT ATCCRtEIS OFBBI 'QlllCIC-4' PARTWJ.Y M~DEDCHMl!ERBED. PIACE 6"CONCAEIE SAND UNDER etw.IBIR RCM!l.11 ROWS CF 11 otAMIERB • 55aw.IBERS -. -· ( ,,. / / \ ,,. v,,. -El0811NG-- ABBORPTICN AREA TD BE ABANDON BJ PCNJ ~r#'"/ y .,,,,.,,,, ,,,,,,,,,-FRENCH DRAIN (1) SITE PLAN AtJD PROPOSED .~~j ALL ~ 1rn~rn1 W 38 Fllur_ DIM_ ~.-81823 Phmte87~6'M adlQlbrf'IClll_.I>_,. HoUI Residence ..eo2~113 W Ccanty, COlcndo ..._l*lmbr. Cl1111 oO ~ DRl\IE :HIEDAOOM RESIDENCE / / -. / ......._ ·4' CV.6DR-S5 m:Y.mUNE WITH CLEAHCUr (MIN 2llo 81.ClPETOTANIC) - El0611NB 1ooo.GAl.LON TWO.c:OIFARnEHr, CONCRE1E TANK WITH EFFWEHT FL1ER TO REMAIN II USE ElGSTINB 4" DIA B~EM:R UNE TO D-llOX !NIN 1%) DRAWl'ICIS MUST E USED IN CON.AJNCTICIN WITH IE!IClN LEI IERDA1ED ltl/18.'" ~ l~W 1111 .... llr. CBO -·'•Cl ll'J: RHPI -er.-W1.0 8-lal'4 ~--aMMJ.VAl.VEOCl'Jl!ll BQXDRIAllA\1DI VAl.11E llCIXATGRADE _.......--ATllloCll CAPOllllllEADEll ctEMCUI' AllBil!LY (_.~.'~.y 41.. .......... ' . ... 1JO ~801: -T08Ll'PQIU -·:.: .. ~· ..... :·~···:>:>~·. '· .. '· •' . . . . .·: ·~ ..... ·:: ,'·: ' 1\ I ·~;:··. , r .~ -...::<•I 4' PVC PIPE CUTTO Fir +~~JJ!5 LIE HCU!llAWTO CUT 111RllTDPOF e•R.An-- B'OFTOPllOIL TOBE REMCMiJAND PLACED ON TOP OF MOUNJ TO PROMOlE RE-llEGEl'ATIDN-~ GRADE , •••• ·:·I @)CHAMBER DETA~~S.. ·4" DIA INl!PECllCN HAHG<I' DIAPERFQW.TED PORT AT CJPl'ClllT'E CXIVE\S OF EAQt IED GRA\lfl I BIS 'QIJIC~' STANDARD CllAlll!ER PIPE TO ~DERSlllE OF CKAMBB'UI, ENTIRE LENGTH OFROW,wmt21PTES --= BED Musr E LEVEL GROl.WDWAlERAT 4' BB.Off <lRAIJE G) BED SECTION SCARIFY SURFACE ALL ~ 1rn~rn1 W 38 Fllur_ DIM_ ~.-111823 Phmte87~6'M adlQlbrf'IClll_.I>_,. Mi MWWWf HoUI Residence ..eo2~113 W Ccanty, COlcndo ..._l*lmbr. Cl1111 ~ l~W 1111 .... llr. CllO -·'•Cl ll'J: RHPI -er.-W2.0 8-2al'4 twfB4"D PIPETOU! CHAMllSlll, ROW,wmt 4" PVC IEADEA8 (1t.F.W. TO DISIRBl11' lilOX,~ TDGIWlE 4° DIA EFFUSJI' INLET LWE //1 MW 1% '"'I~, FROM TAN< ALL ~ 1rn~rn1 W 38 Fllur_ DIM_ ~.-81823 Phmte87~6'M adlQlbrf'IClll_.I>_,. .QUOt4(TM) ~D CAPS (.I) CHAMBER BED fmL!'t;!.,, HoUI Residence ..eo2~113 WCcanty,COlcndo ..._l*lmbr. CHiii ~l~W 1111 .... llr. CllO -·'•Cl ll'J: RHPI -er.-W3.0 8-3al'4 DESIGN 1-BBJ,__EllCE (75GAl.JPERllONOo\Yx2PERSONllAIEDAOCMx3BEDROOMS) AVERAGE DAILY FLOW• Q •48110ALLClN9 TANK: MINNi...1CJlllMW.1.DN TANK USE EXISTW.G 100l>GALLON, ~TANK ABSDRPl'ICN AREA: 80L T'IPE2, SANDI.YI.ON.I CAl.all.ATED STA• Q\.TAR 450 ~I0.8GAIJSI' ~ 750 Sf GRAVITY BED 11111SFX1.2•111111 BF ~llOOX0.7~83081' 1311IF112SF«llW.IB~•1111 CIWll!ERS 4ROWSOF14 'QIJICIC4' CHAMBERS WIDTH CF BED~ 12 FEErWllE LEHGTH CF IED • 14CHAMERS•1!11 FEET LDNG TOTH. F001PRM ~ 12 FEEi' x 5e FEET ALL ~ 1rn~rn1 W 38 Fllur_ DIM_ ~.-81823 Phmte87~6'M adlQlbrf'IClll_.I>_,. FINISIEJ GRADE ~-6L~N PYCCAP DO NOT Ill.IE " -j ~ rB'FWEHl'UIE·4" I &aiBJll.E 400R4' 8DR :Ill P.V.C. 9~Lll't5· 4'SCl£DULE 411P.V.C.~ INWLATEDCOPPER TRACER WIRE MAYBE INSl'A! Im TO LOCATE UIE IN FU1URE @CLEAMOUT DET~.L--·· BOX MD COVER llROUOHTTO GRADE l CONCREIELD~ Fll'SHED~ 0000 CUT1Enl DISTRIBUTlON BOX IN.El' IW'R.E ® D-BDX DETAIL HoUI Residence ..eo2~113 WCcallty,COlcndo ..._l*lmbr. CHiii r.Df 111 svu ~ l~W 1111..,... a,, CllO -·'•Cl ll'J: RHPI -er.-W4.0 8-4al'4