Loading...
HomeMy WebLinkAboutOWTS DesignFebruary 15, 2023 Jill Mueller illIkemuellp-r mail.com 129 CAINs LANE CARBONDALE. CO 81 623 970.309-5259 CAR LA.OSTBE RG@G MAi L.CC7 M Subsurface Investigation and onsite Wastewater Treatment System Design 3 -Bedroom Residence + 2 --Bedroom Accessory Dwelling Unit (ADU) 180 CR 109 Garfield County, Colorado Julie, Project No. C1781 CSO Inc. performed a subsurface investigation and completed an onsite wastewater treatment system (OWTS) design for the subject residence. The 2.339 -acre property is located outside of Carbondale, in an area where OWTSs and wells are necessary. Legal Description.- Section: 1 Township: 7 Range: 89 A TR. IN NW1/4 Parcel ID: 2395-012-00-123 SITE CONDITIONS A 3 -bedroom residence and 2 -bedroom ADU are currently developed on the property. Bath are served by an existing OWTS. No records on this OWTS were available from Garfield County. The proposed OWTS design is a repairlreplacement of the existing OWTS. The residences are supplied potable water from a private well on the property. The existing well is located in the northeast corner of the property. The well is located at feast 5D -feet from the proposed septic tanks and at least 1 DD -feet from the proposed soil treatment area (STA). A ditch flows to the south of the existing driveway. The ditch must be at least 5Q -feet from any OWTS component, or it must be lined or placed in a culvert. The existing pond and stream on the property will remain and the lining will be inspected and repaired, if needed. The fining mush be a minimum of 30 mil thickness. Na OVVTS component will come within 10 - feet of the lined water features. The Roaring Fork River runs along the northern portion of the property. No OWTS component will come within 5D -feet of the giver. The proposed soil treatment area {STA} location is relatively flat, with a 1 to 2°lo slope to the northwest toward the Roaring Fork River. We recommend discontinuing or limiting irrigation in this area ince the new STA is installed_ 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 SUBSURFACE The subsurface was investigated on May 27, 2Q22 by digging two sotl profile test pit excavations (Test Pits) A visual and tactile soil analysis was completed by Carla Ostberg at the time of excavation. ' The materials encountered in Test Pit #1 consisted of medium brown topsail to 2.0 -feet, underlain by light brown sand and cobbles to maximum depth explored of 5.D -feet where groundwater was encountered . The materials encountered in Test Pit #2 consisted of dark brown topsoil to 1.0 -foot, underlain by medium brown sand and cobbles to maximum depth explored of 5,.5 -feet where groundwater was encountered. The ditch to the south was running at the time of our subsurface investigation. STA sizing is based on R-0, Sand with rock content greater than 35°/0. For the purpose of the OW_FS design, we are estimating high seasonal groundwater at approximately 3 -feet below native grade. A partially mounded, pressure -dosed, unlined sand filter with a minimum of 3 -feet of sand flier material (Secondary Sand)is proposed. A long term acceptance rats (LTAR) of U.8 gallons per square toot will be used to design the OWTS, Test Pit #1 Coria Ostberg holds a Certificate of Attendance and Examination from the CPOW Visual and Tactile Evaluation of Soils Training. 5 46. ILf r ir � �. *� _ A � �* 1i Backfill Test Pit #1 r ",q.' IL lop RL AV / � F� y !� df A Single -grain (sand .� err. - - �• yy dr dke I 7 y � 9- '.3 �;. dig t_. S V Ditch to the south 4f .� jpr r - - S �. u •�'�,}�_`�#fix +� R ' I � ��.,�r�riFr # _ � Teti �: • � L A. Ft r -�� FfW i l"-- i i x { 1p 940 } ` ! rt 4 iL r AL_�T' 9� •' t L Groundwater in Test Pit #1 at 5 feet Test Pit #2 El f1p � "" .'07 .0o " y s c A. a 1 A� y Backfill j `~ r 9pl alp ' .0v `, .'Idt *- M j 9.1w �O T� %p qRW ! P-9 dk Fi c i S FF i � F 90 O mop }} 70 _ I W • * + 191 rM s +-� %SOL If _ *; 1411� 49 0 30 IL w L T r i Page Page 6L. j& % ;, 1W dr I w, ilk rT .. + I ■ hL Ad Groundwater at 5.5 -feet in Test Pit #2 r h DESIGN SPECIFICATIONS The existing septic tank will be pumped and removed The existing STA will be abandoned in place. Design Calculations. Main House = 75 GPD x 2 people/bedroom x 3 Bedrooms = 450 GPD ADU = 75 GPD x 2 people/bedroom x 2 Bedrooms = 3Q0 GPD Design Flow = 750 GPD Tank Capacity ^ Min. 1500 gal + capacity for pump LTAR = 0.8 GPD/SF 750 GPD ! 0.8 GPD/SF = Min. 937.5 5F Page The OWTS design is based on 3 -bedrooms in the Main Residence and 2-bedroorns in the ADU An average daily wastewater flow of 750 GPD will be used For the purposes of this OWT'S design, the existing Finished Floor (FF) elevations of the Main House is 59Q9.5' and ADU FF is 5910.22'. The existing sewer lines from each residence may be explored and use continued if they ars found to be in good condition. CBS Inc. should be notified of any discrepancies or problems with grade elevations of proposed components during installation of the OWTS. OWTS Component Primary Tank inlet Invert � Approximate ground elevation 5907'/ Estimated I nvert elevation 5905' Automatic Distributing Value Estimated elevation 590i" Infiltrative Surface Minimum Elevation Approximate horizontal distance from ADV 99' 1 � min. 2% fall 1 min. 24.75" fall Approximate horizontal distance from Main Huse 32'1 min. 2% fall 1 min. 8" fall Approximate horizontal distance to ADV 28'/ min. I% rise for drain back 1 miry. 3.5" rise Approximate horizontal distance 70' l min. 1°/a fall ! man. 1.25" 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 The 4 -inch diameter sewer lines exiting the ADU and Main House must have a double -sweep clean out and a minimum 2% grade to the septic tank. These sewer lines may remain if fond to be in good condition. The system installation must include a 1500 -gallon, two-compartment Valley Precast concrete septic tank with an OrencoO Biotube Effluent Filter on the outlet tee followed by a 500 -gallon, single -compartment Valley Precast concrete pump chamber with an OrencoO Biatube Pump Vault and an Orenco@ PF3005 pump. Risers must bring the manhole lids to grade for access. It more than one riser is added, an extension handle must be installed on the effluent filters and float tree. The floats should be yet to dose approximately 62 gallons each pump cycle, allowing approximately 3 gallons of drain back after each pump cycle. A pump curve is enclosed. The control panel for the pump must be located within line of sight of the septic tank. We recommend Valley precast out of Buena Vista be contracted for start-up of the pumping system. Pump Table Dose Range dose Sitting Float Separation Pump Criteria Max = 190.5 gal. (750 GPD x 25% + 3 gal drain back) fit gallons/dose 500 gallon singe -compartment Valley Precast concrete pump chamber 24.4 gallons per minute (GPM) Min. 39 gal_ (9 gal x 4} + drain back gal 3 gallons drain back (28'/ 1 .5" diameter puma line) 6" on/off float separation (10.4 gal/inch) 18.E feet total dynamic head JD Effluent will be pressure dosed through a 1 5 -inch diameter pump line to a partially niounded, omlined sand filter. The sand filter will be divided into two beds, each 13'x 36.25' with some room between beds for plumbing for a total approximate length of 74 5 -feet. The excavation for the sand filter will extend 3.0 -feet below native grade. A minimum of 3 -feet of sand filter material will beinstalled in the over -excavated footprint, resulting in the top of the sand filter at approximate native grade, Sand filter material mast be clean, coarse sand, all passing a screen having four meshes to the inch. The sand must have an effective size between Q_ 15 and 0,60 mm. The uniformity coefficient must be 7.d or fess_ Material meeting ASTM 33, 7 for concrete sand, with three percent or less fines passing 200 mesh sieve may be used. b gradation of the sand media must be provided. Effluent will be pumped through a 1.5 -inch diameter pump line from the pump chamber to an OrencoO automatic distributing salve (ADV), model X4{34. This pump Ione must have a minimum 1 %grade for proper dram back into the tank after each pimp cycle. The ASV must be placed a high point of each zone in an I nsulated riser with access from grade. Screened rock must be placed below the ADV to support the ADV and to assure the clear pies exiting the ADV remain visile for future inspection and maintenance Leve), 1.5 -inch diameter manifolds will connect two laterals on each bed see 1N3.011 Partially Mounded Sand Filter Plan). Laterals must be 1.5 -inches an diameter with 5132 -inch diameter orifices facing down, spaced 2 -feet on center, installed on the GeoNiatT"" with the gray filter fabric over the laterals Laterals should be placed 2 -feet from the edges of the bed leaving 3' between the manifofded laterals and 3.4 -feet between the sections connected by the ADV. Four 39" wide GeolVlatTm must be placed an the 13 -foot wide bid. All material associated with the GeoMatr" installation must be proprietary products associated with the GeoMatT'A, including orifice shields and geotextile fabric. Manufacturer instructions must he followed regarding installation of the GeoMatTPA . Each 1.5 -inch diameter lateral must end an a sweeping ell facing up with a bail salve for €tushing. Laterals must be covered by the gray GeoMatTm soil separation fabric and at feast 1 -toot of topsoil or other suitable sail able to support vegetative growth. Thea shall be no cobble -sized (2.5") or greater rock in final cover over the GeoVlatl-". Inspection ports must be placed into the sand filter material on each corner of the beds The mounded portion of the STA must have a minimum 3.1 slope (horizontal -.vertical); therefore, the basal area will extend approximately 5.0 -feet beyond the sand filter on all sides (with a mound height of approximately I' 4" above native grade). Soils in the stoped perimeter meas of the mound must be well draining and able to support vegetative growth. This soil must be approved by this office prior to installation. The mound must be crowned in a manner to promote drainage off the STA. 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 installaVian of the DWTS. Requests must be submitted, in writing, to our office for approval prior to installation. Component technical data sheets are available upon request. COMPONENT Septic Tank Effluent lifter Pump Chamber Task Deadmen Pump MANUFACTURER Valley Precast Orenco& Valley Precast Valley Precast OrencoO Blotube ProPak Pump-J-0-r-en-66CF6 Package Tank Misers and fids ADV OrenCOCID ren MODEL NO. tem # 750QT-2CP Item # 500-1CP-HH Item # DM PF300511 Y2HP 120 Volt BPP36DD V6404A COMMENTS 2-comparfinent concrete septic tank Full size 4" diameter effluent filter Ingle -compartment ump chamber with high ead pump nti-Buoyancy (depending n burial depjt_ _ vauit, HIter, Control Panel (demand dose Do-u-ble-wailed PVA Risers and Lids (24" diameter) i _ _ 11.5" Inlet and cutlets Page 8 Construction must be according to Garfield bounty On -Site Wastewater Treatment System Regulations, the OWTS Permit provided by Garfield County Building Department, and this design. PERMIT APPLICATION INSTRUCTIONS An QWTS Permit Application must be submitted to Garfield County Environmental Health .Department. htt s //www.-garfield-countycvmlenv'ironmental-healthl#`iles ccalsites115lQWTS-A lication-Com lete- Packet-Dec.-219 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 Enol approval of the OWTS installation Communication between the installer and this office is expected throughout the installation. INSTALLATION OBSERVATIONS CBO Inc. must view the OVVTS during construction. The OVVTS observation should be performed before backfill, after placement of OWTS components. Septic tanks, distribution devices, pumps, dosing siphons, and ether plumbing, as applicable, must also be observed. CBS Inc. should be notified 48 hours I n 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 an the property. This sketch is most easily provided an Sheet W2.0 of the OWTS Design Packet. Photographs of the installation and final cover are also requested to supplement aur instaliatian 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 rats, 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, erasion and sediment control measures shall be implemented and maintained an 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 OVVTS servicing tie property, The property owner is responsible for maintaining service contracts for manufactured units, alternating STAB, 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 knot 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 erasure that no additional water is being discharged to ANTS For example, a running toilet or beaky 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, oras needed. If the OWTS consists of a pressurized pump system, we recommend the laterals be hushed annually, or as needed. The homeowner should pump the septic task eery 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 OVVTS Grease should not be placed in household drains. Loading from a water softener should not be discharged into the OVVTS. No hazardous wastes shau:d be directed into the 0VVTS- Mechanical room drains should not discharge into the 0VV_FS. The OVV-FS is engineered for domestic waste only. ADDITIONAL CONSTRUCTION NOTES If the design includes a pump, weep hales must be installed to allow pimp 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 die 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, CBD Inc. should be notified. All OWTS constriction 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. (?ah Ca D.�bch� Carla Ostberg, MPH, REHS r" . . CC/ENGINEERING Fronk Construction h7. 1131.-24- Road Grand Junction, GO 81505 970-25"572 By-OLReviewed I c F+ri■■** t � r ■ t -IP61140 50 T T ,J�•ge i Pe 1 dop /rn m og N OIFNI CL ZIMP CL Fir co jJ,orJ %OWN lie _i, � � . t ,�y, hu, W;� < 0 z c) t40Ji . JYz �- �- -j 'a N Q CIO Z 49 /A < 0 0007 a�ji���/�ii�ij��, i WWW>N`> U) LLI CL 1E LU 0 00 0 r CL CL CL OL wo w i;li �a��owx Ml..�� CL CP ILL L- Oz Z z 4e? 4b/ �OW O 4h Zder�� j � y X J~� Z -- ISI � � UwaQ�mz 9 41 frp Vs�O�4. Q�U�K M1�/ �a5 wFWNw0 ,pati � a 3 =O�Z�=O H L Q W Q (!] LL 4r OL qe/ 47 s a - i Q co N CO 0 0 ID c co LO z IN E o Iq CD 0 L) o EDa- co co N 0 0 ID CF) ICU LO m IN E o Iq CD 0 L) o @) co la) 0 0 T-- .. t 1 0 p y' N C) CN l w LIP LJ r 0 '.n -4 me. -Joe F F -w �W t Vz �Z CL a � Z O M. tto _3�rsS 6 d 0 �w'�z � w CO In ¢— � WZ �� oF- F- Vdi 0 � w LL Z �� / aZ z�m z0 w Z a - -- apvYLL o¢ � 1 %�// U) (f) I F- M CL `° w CL�zv ti cn3z LU co 2em W - LL uj CL III T-4 C) 0 0� o /j��j �/.c' / zFm�.� :E C) // // �3: J1,111111 LLI dr il i / -F AZ Ail 0 �Cjo 110�/ Af je I ���/�/��//�/�/� I m 0 IN w CL) cn Li LL 0 0 0� Ll CL 0 CD co 0 0 REM 0 cr) Ll LLI-r cu m E CO p y' N C) CN l w LIP LJ r 0 '.n -4 me. -Joe F F -w �W t Vz �Z CL a � Z O M. tto _3�rsS 6 d 0 �w'�z � w CO In ¢— � WZ �� oF- F- Vdi 0 � w LL Z �� / aZ z�m z0 w Z a - -- apvYLL o¢ � 1 %�// U) (f) I F- M CL `° w CL�zv ti cn3z LU co 2em W - LL uj CL III T-4 C) 0 0� o /j��j �/.c' / zFm�.� :E C) // // �3: J1,111111 LLI dr il i / -F AZ Ail 0 �Cjo 110�/ Af je I ���/�/��//�/�/� #-- co r -- C3 r 0 m 0 IN CL) 2 ' 0 Low CD co 0 0 -0 cr) CID cu m #-- co r -- C3 r 0 m IN 8 0 -0 cr) CID LO m ccn � CIOcn� ci 0 o e c o MINIM 0 0 CL� V-- 0 w zw ; �IdI LL z LU 1 � C cn { I G CD CL ui CL NO LLIin L5 C C) 0 F- IF- z > � LL 0 of z 0 o Iii Of � > CV) WC) 10 Li ujV- LC) z CL CD< _j z < ZC) LO z LL w uj 0 CL W e---- 0 0 0 >LJ 11 � w LLJ x C) 0 < ]E Cl OL LU Z W r" LL LZ (.) LU <uLj cn a) < LL %-.Ol v- -j LJL o L<L 0 z U) 0 LLI0 F- CL J W J Z W � Z � o U) U m C) LL > o a z U W C) N a� o I U) LU IT cr 0 WR 0 L) 0 (n CL Y) w w C) ■ MEJ z z o Z�l LLI * fps { i r ..■ L e dp ; # -r i; T7 _ qk alp ;r■ �� -P r 4# . • * ,tom � L � _-'�� •��' J� ! ■ +�# f' + a + p ■w r ■ r �' ` # Z T ■�■ .� F . I dp■ ••• qrT 4 % T i 41 1p -P d. #i P, f * 4p pm+ F ` r !` -W r .dp -PP 4h - art ip ■� i *Fi r ■ * f F T 4 '� i T * ■* yi ■ ,� W i }� ■ /!F , s1, + •■ dp - f d6 i t_ ■ r• fl tiL t lZ w 0 Z L � w 0 Cm I8W W L&. w ■ U- LLQ 2 Z) LL ag >1 CL - C Q 0 iWUJ o L cci L) CY) I�C9O Lo ul z C Lo 0 CL i MEJ z z o Z�l LLI * fps { i r ..■ L e dp ; # -r i; T7 _ qk alp ;r■ �� -P r 4# . • * ,tom � L � _-'�� •��' J� ! ■ +�# f' + a + p ■w r ■ r �' ` # Z T ■�■ .� F . I dp■ ••• qrT 4 % T i 41 1p -P d. #i P, f * 4p pm+ F ` r !` -W r .dp -PP 4h - art ip ■� i *Fi r ■ * f F T 4 '� i T * ■* yi ■ ,� W i }� ■ /!F , s1, + •■ dp - f d6 i t_ ■ r• fl tiL t lZ w 0 Z LU � 0 Cm I8W W L&. w ■ U- LLQ 2 Z) LL ag MEJ z z o Z�l LLI * fps { i r ..■ L e dp ; # -r i; T7 _ qk alp ;r■ �� -P r 4# . • * ,tom � L � _-'�� •��' J� ! ■ +�# f' + a + p ■w r ■ r �' ` # Z T ■�■ .� F . I dp■ ••• qrT 4 % T i 41 1p -P d. #i P, f * 4p pm+ F ` r !` -W r .dp -PP 4h - art ip ■� i *Fi r ■ * f F T 4 '� i T * ■* yi ■ ,� W i }� ■ /!F , s1, + •■ dp - f d6 i t_ ■ r• 11 D z V) 0 Lu 0 P CL lZ W o CU � 0 LL) a �C)w0 co >1 0 Q iWUJ OW L cci I�C9O ul C 11 D z V) 0 Lu 0 P CL CU CO 0 co >1 0 L cci C CL i co 0 C i — 0 0 - OL C) w 0 F— U) cn of w LL 0 z LLLi V) 0 i3 D CD II CD C) - OL LLJ . w F - w x Lj C OL i • a a + y' C) L) 0 < < C) , U) Ltj C) cr) !} ! ui E c 4c a_ z 0 1 CL .j(n w n w D F- 0 z u a LO (n LLIw LU LLQ D 0 T 0 y z 0 P: 0 z CL F- U) w Wj I 0 ryl CL qr- I b z CL U) LU F- LU ..J LL 0 CL 0 V) 0 0 z 4 L1 J 0 CL 0 3:0 m a a D (nCL O H z 3:0 crm 0 w 2 V -- r _ ■ a rt i + r f m i # * + i + * ■ * + * 6 ■ # ; 4 i U) W Co 03a U d z z 3:0 m z ww i>w ❑ F' Z Z Q 0W 0 i' fi i= �i t' a7 ■' !■ ■ 4 r W LL m W m .J w w U +'' Z Q w O 2 Q 0 3: W 0 F' Q In � 0 Z 0 NE D D W LX Ln 0 r _ ■ a rt i + r f m i # * + i + * ■ * + * 6 ■ # ; 4 i U) W Co 03a U d z z 3:0 m z ww i>w ❑ F' Z Z Q 0W 0 i' fi i= �i t' a7 ■' !■ ■ 4 r Z-0 H Q LU d w 0 C� z LU D z C� 0 z a w z w CO =w z� o0 LUQ �- d �z w� w a� zm 0 133 - H-ld3a co LL W .J w w F - +'' w Z-0 H Q LU d w 0 C� z LU D z C� 0 z a w z w CO =w z� o0 LUQ �- d �z w� w a� zm 0 133 - H-ld3a co cq QDco 0 LO u 0 NE Ln 0 M CO CD .aJ %.. 0 CZ in — 0 r C