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Home My WebLink AboutOWTS Design33 FOUR WHEEL DRIVE ROAD CARBONDALE,CO 41623 97c-.3C9.5259 CARLA.OSTBERG@GMAIL.COM sr.:t"t't(' (:()ì\st :r.'l'rì\I'f; April4,2021 Project No. C1574 Barbara Dills Barbara.d ills@qmail.com Subsurface lnvestigation and Onsite Wastewater Treatment System Design 1-Bedroom Residence + 3 Future Bedrooms TBD CR 102 Garfield County, Colorado Barbara, CBO lnc. performed a subsurface investigation and completed an onsite wastewater treatment system (OWTS) design for the subject residence. The 5.739-acre property is located outside of Carbondale, in an area where OWTSs and wells are necessary. Legal Description: Section: 28 Township: 7 Range: 87 TR lN SWNW 5-74 ACRES Parcel lD: 2391 -282-OO-1 12 SITE CONDIT¡ONS The property is currently undeveloped. A 1-bedroom, residence is propbsed with 3 additional bedrooms contemplated in the future. A detached garage with no plumbing and Barn/Office with aTzbalh is also proposed. The property will be served potable water from a private well located approximately 135-feet from the northeast pioperty corner. The well will be located greater than 50-feet from the proposed septic tank and greater than 1O0-feet from the proposed soil treatment area (STA). The proposed STA location has an approximate eight percent slope to the south. The proposed area is located south of the proposed residence and is covered with sage and native grasses. There should be no traffic or staging of material overthe future STA site to avoid compaction of soils prior to construc{ion of the STA. SUBSURFACE The subsurface was investigated on November 2O,202O by digging two soil profile test pit excavation (Test Pit). A visuat and tactile soilãnafsis was completed by Carla Ostberg at the time of excavation.l The materials encountered in Test Pit #l consisted of medium brown topsoil to 1.O-foot, underlain by whitish to tan calcareous clay matrix with angular rock to a maximum depth explored of 2 to 3.0-feet. Practical digging refusal was en@untered on a large boulder- No bedrock or groundwaterwas encountered. I Carla Ostberg holds a Certiftcate of Attendance and Examination ftom the CPOW Visual and Tactile Evaluation of Soils Training. Page2 The materials encountered in the Test Pit #2 consisted of medium brown topsoil to 1.0-foot, underlain by whitish to tan calcareous clay matrix with angular rock to a maximum depth explored of 5 to 5.S-feet' Digging beyond 5-feet was diffìcult. No bedrock or groundwater was encountered. A sample of the soil was taken from Test Pit#2 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 firm to extremely firm. Soil texture was more gritty than smooth- White digging was difficult and depth was limited in all test pits, including those gxcavaled for the Subsoil StuOy toTlnJFoundation by Kumar and Associates (enclosed), soils were consistent with Soil Type 2. A long term acceptance rate llfAn¡ of 0.5 gallons per square foot will be used to design the OWTS. Beginning Test Pit #1 with refusal at approximately 2 to 3-feet Page 3 Test Pit #2 Sieved sample Backfill Material left in sieve are PEDS, not rock Peds were firm to extremely firm Page 4 Ribbon less than 1-inch in length Sidewall of Test Pit DESIGN SPECIFIGATIONS Design Calculations: Average Design Flow = 75 GPD x 2 people/bedroom x 4 Bedrooms = 600 GPD LTAR = 0.6 GPD/SF 600 GPD / 0.6 GPD/SF x 1.0 (gravity trenches) x 0.7 (GeoMat with 6" sand) = 700 SF The OWTS design is based on 1-bedroom with 3 future bedrooms proposed for a total of 4 bedrooms. An average daily wastewater flow of 600 GPD will be used. Due to the nature of the soils and limited depth of exploratory digging, we are proposing GeoMatrM trenches which will be underlain by 6-inches of soil. We feel this design will allow for the trenches to remain shallow and the additional sand will enhance treatment of the wastewater. Page 5 For the purposes of this OWTS design, Benchmark Elevation at grade 7129' (finished floor elevation) has been established as 100'. The sewer line will exit the residence at approximately 98' (7127'). CBO lnc. should be notified of any discrepancies or problems with grade elevations of proposed components during installation of the OWTS. The 4-inch diameter SDR-35 sewer lines exiting the residence and Barn/Office must have double-sweep clean outs and a minim um 2o/o grade to the septic tank. Plumbing in the BarniOffice will be an auxiliary use to the main house. The sewer line must have a clean out at least every 100-feet. The system installation must include a 1S00-gallon, two-compartment poly lnfiltrator@ septic tank with an effluent filter on the outlet tee. Risers must bring the manhole lids to grade for access. lf 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 four GeoMatil 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 be 36-inches wide with a minimum of 6-inches of sand fìlter material placed in the trench. 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 meeüng 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. 39-inch wide GeoMatil will be placed on top of the sand filter material the entire length of the trench. The GeoMatil is 39-inches wide and may curl up the sides of the trenches slightly. A 4-inch diameter perforated pipe will be placed down the center of the GeoMatru, under the top layer of fabric. The STA will consist of 4 trenches, each with 60 linear feet of 39-inch wide GeoMatil for a total of 240linear feet and720 sqaure feet. All material associated with the GeoMatru installation must be proprietary products associated with the GeoMatru, including the geotextile fabric. Manufacturer instructions must be followed regarding installation of the GeoMatrM. There must be at least 4-feet of undisturbed soil between each trench. lnspection ports must be installed at the beginning and end of each trench. The front inspection port will be placed to the side of the GeoMatm and the end inspection port will be tied onto the end of the lateral. Ports may be cut to grade and placed in sprinkler boxes for access. There shall be no cobble-sized (<2.5") or greater rock in final cover overthe GeoMatru. OWTS Comoonent Minimum Elevation Primary Tank lnlet lnvert Approximate horizontal d ista nce 37' I min. 2o/o slooe to septic tank / min. 9.25" fall Distribution Box Approximate horizontal distance 1 1' / min. 1Yo fall to distribution box / min. 1.375" fall lnfiltrative Surface Approximate horizontal distance to farthest trench 40' i min. 1o/o fall to STA / min. 5" fall Page 6 COMPONENT SPECIFICATIONS The component manufacturers are typical of applications used by contractors and engineers in this area. GBO lnc. 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. Construction must be according to Garfield County On-Site WastewaterTreatment System Regulations, the OWTS Permit provided by Garfield County Building Department, and this design. INSTALLATION CONTRAGTOR CBO lnc. 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 thís 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 lnc. 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 lnc. should be notified 48 hours in advance to observe the installation. ln 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 inigation 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. COMPONENT MANUFACTURER MODEL NO.COMMENTS Septic Tank lnfiltratorG)tM-1530-ZUP I 500-gal lon, two-compartment ¡olv seotic tank Biotube Effluent F¡lter Orenc@ 2) Full Size Effluent F¡lter and ìousrnq Distribut¡on Elox PolyLok Distribution box, risers,lid, and llow eoualizers 14) GeoMatrM GeoMatrix Systems, LLC 240,GeoMatrM (39,, wide sheets) Page 7 OPERATION INFORMATION AND MAINTENANGE The property owner shall be responsible for the operation and ma¡ntenance of each OWTS servicing the property. The property owner is responsible for maintaining service contracts for manufactured units, altemating 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 additionalwater 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. lf an effluent filter or screen has been installed in the OWTS, we recommend this filter or screen be cleaned annually, or as needed- lf 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 GONSTRUCTION NOTES lf 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. lf soil conditions encountered are different from conditions described in report, CBO lnc. 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 lnc. (ø.n(,2 }xúxng Carla Ostberg, MPH, REHS N DRAWINGS MUST BE USED IN CONJUNCTION WITH DESIGN LETTER DATED O4IO4I2O21 SCALE:1 =5{Y{" -\-. \\\ 3\\ . I LINE ,þ I I THE LOCANON OF PROPOSEO NOT THE F(oI¡\ P Hott) RESULT OF A PROPERTY SUR\iEY. l}IE LOCAÌìONS APPROX{MA'IE. IT IA THE HO{TIEOWNERS OUTY TO ENSURÉ AII ANO IMPROVEMENT LOCATIONS ARE ACCURATE.LINES AND SETBACK DISTANCES SHOULD BE CONFIRMÊO SCALED FOR PRINTING ON 1 I' X 'I7 PAPÊR, TO EXC"ÄVAION. ^ SIÏE PLAN\r,-1æF GARAGE 7L30 \\\tt ltrl\\\tt \ BARN & OFFICE\.WITHTOILTTAND - f-- + \-\\--/- 33 FürWÌHlDrivô RGd Carbondale, Colorado 816æ Phone 970.309.5259 @la@sllsrylGepl¡c.æmffi Dills Residnece TBD CR IO2 Garfiold County, Colorado Pm¡sct Number: C1574 l}alet c!'Ic!l!2121 lo*¡snø ov, cso lDrawn bv: DD w1.0 Shæt l0F4 ð4 L Ò Og I t-- DRIVEtVAy -'7L30 \ /----\*-- --\------ PROPERTY LINE --//// aat' _\BARN &OFFICE WTH TOILET AND SINK SEWÊR LINE FROM BARN/OFFICETO - - WYE INTO SEWER LINE FROM RESIDENCE BEFORE SEPTICTANK \ : - IíXÞGALLON, TWO-COMPARTMENT SEPTIC TANK WITH EFFLUENT SCREEN / - - 4 ora sonaì siwrn nr.lere BM 100' (FF 7r29) (MÑ.-f%sLoPE ro srA)\ orsrnreuirñ-Box- - ATGRADE - - -¿t,i'iÃ=**?ver€r*AeTjrE' /___-*/ --ll-*TP -oo"*"*gb'^$ll'l"PORTATENDOFEACH -- - - UüERAL_ _ 1-BEDROOM RESIDENCE PLUS }FUTURE BÉDROOMS ffi 33 Four Whæl Orlvs Ræd Cãñondåle, ColoËdo 81623 Phore 970-309.5259 6rlå@allærv¡æpl¡c:m Dills Residnece TBD CR 102 Garffeld County, Cdorådo Proi€clNumber C1574 04t4412021 by: CBO by: DD w2.0 Shæt 2 0F 4 CBO lnc.33 Four Wha6l Driw RoadCårbondels, ColoEdo 81623Phone 970.309.525ScarlE.ostbsrg@gmail.com4'T'ASDR.3s SEWER LINE FROM TAI{KDrslRtBUnON BOXW''}I ACCESS AT GRADEFln¡ôhed GEdElZ Mlnlnum Crcr4" P€rfoEbdDlstlbudon PÞe4'4" DIASDRSSTO EACH BEOGeMat394' DIA SDR-35 INSPECTIONPORT AT END OF EACHLAIERAL,AGEOMAT SECÎON\9t-DIA PERFRATEOPIPE I.ATERÁLGEOMAT il4 ROWS OF 60 GEOMAT ilON EACH O'SAND INTRENCH CONFIGURATIONPLACED ON TOP OFlnsp€ctonGRADË\1./\1./¡/BOX ANO COVER BROUGffi TO GRADEFsbdc21iCONCRE'IEDúibu6ontstpð4' OIA SDR-35 SEWER LINE(MIN 2% SLOPE TO TANKMtN, r% TO STA)ffi6trMIN. €f SAÑDSCREENEDOR SAND FORBEDDING3" MtN.BAFFLE ORANGLÊD PIPETO BÊ USED'sÊ6NDffiSvEFffi SEE'0.15-0.æmuNrFouñæffistr9¡% FNB PßINGffiSIMs¡AT INLET/ã sfA sEcTroN\t-ffiojtsENçH-eEAh'E/i DIS'IRIBUTION BOX DEÎAIL\y-.--lmOUTLETSooooDllls ResldneceTBD CR 102Gãrffeld County, ColoradoProjec{Number: C1574lo*a, ututzoz'ttes¡gn"d uv, csolorawn ov: Oow3.0Sh6êt 3 0F 4 CBO lnc.33 FourWhælDri€ RædCarþondalê, Cdomdo E1623Phons 970.309,5259éde.Gtb€rg@gmdl.æmOESIGNI.BEDROOT REgIDENCE + 3 FUTURE BEDROOMSC/5 GPD x 2 PERSONS|/BEDROOM x 4 BEDROOMS)WASTEWATER FLOW È dX' GPDSTA TO WAIER CÆURSEg)'N/ASTATO WELLr00'196'SIA TO HOUSEm'31'SEPTIC TANK TO WATER COURSE50,N/ASEPTIC TANK TO WÊLL50'159HOUSÊ 10 SEPTIC TANKN35OWTS COMPONENIS ANDPHYSICAL FEAÎURESMINIMUM REOUIREI)SEIBACKAPPROXIMATÊ PROPOSEDSETBACKrANKMIN. 1250 GAILONSUSE ISOGGALLON, TWGCOMPARTMENT POLY SEPIIC TANKSOIL TREATIvIENT AREA (STA):LONG TËRl, ACCEPTANCE RAÍE (LTAR) = 0.8 G/ù SFCALCULATED STA : OÀTAR È 600 / 0.6 = '1000 SFGR VITY, TRENCHÊS ='1000 SFX 1.0= 1m0SFGEOMAT = 1000 SF X 0.7 = 700 SF / 3 FT WDE ïRENCHES = 234 LINEAR FEET4 TRENCHES, ÉACH WITH SGFEET OF 3Y GEOMATSOIL PROFILE TEST PIT NO. 1F MEDruMBRowNroPsorLb¡I:.:{ WHITISH TO IAN CALCAREOUSCLAYl';..| "oT,äu,nn REFU'AL oN B.'LDEREEN9l= bpsllF,f€1ruday matixSOIL PROFILE TESÎ PII NO. 2012345I7I910DARK SROWN TOPSOILSLIP.ON PVCDO NOT GLUÊINSULATEDÍRACERwlREFINISHED GRADÊTAN, DENSE, CALCAREOUS CLAYMAÎRIXSEWER LINEDIFFICULT DIGGINGTO TANKNO GROUNDWATER OR BÊDROCK ÊNCOUNTEREDDURING EXCAVATION^CI.TAN OUT DÉÍAIL\ár--17træ.ñ SOILS LOG\rr--ñrraEADDITIONAL TEST PITS EXCAVAIED FOR KUMAR A¡¡OASSOCTAÎES SUBSOTL FOUNDATION DESIGN (RËPORÍENCLOSED)Dills ResidneceTBD CR 102Garlield County, ColoradoPmject Numbsn C1574loaø: ulo+tnzllo""¡nnø uy caolDmmbv: DDw4.0Sheel 4 0F 4