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HomeMy WebLinkAboutOWTS Design Report 07.20.2018G Cq ENcINEERING Cronk Constructlon lnc, 1129 -24- Road Grand Junctionr CO 8í505 Grand Junction (970)245 -057 7 . Glenwood Springs/Aspen (970) 640-5029 . Montrose/Delta (970) 640-5029 Fax: (970) 257-7453' Email: ccigj@msn'com ONSITE WASTEWATER TREATMENT SYSTEM DESIGN Date July 20,2018 Prepared by:Thomas A. Cronk, P.E. Cronk Construction Inc. 1129 -24-Road Grand Junction, CO 81505 245-0577 Type of Design: new residential Client:Bill and Renee Holland 348 Shoshone Drive silt, co 81652 970-379-4969 Properfy address: 348 Shoshone Drive, Silt, CO 81652 Tax schedule No.: 2179'232-01-003 Legal Descript. c/o Merv Heincke Extreme Construction 2405 Patterson Road Grand Junction, CO 81505 97 0 -25 5 -81 I 6, mari@extconstruction.com 1.0 Site History The site consists of approxim ately 82.7 acres of uncultivated native soil' Drainage is approximately 15% to the nofthwest in the area of concern. A percolation tesVsoils evaluation was conducted on the property of reference on07l16118 by Tom A. Cronk, registered professional engineer (R.P.E.). The petc excavation trenches were located approximately 75' southwest of the existing shop. The owners wish to construct a two bedroom residence at the site. The 07i l6i l8 site investigation was conducted to provide subsurface design parameters for an onsite wastewater treatment system (OWTS) to serve the proposed residence' Based on results from the 07/l6t18 site investigations, an engineered OWTS design has been prepared for the property. A discussion of developed subsuiface design pârameters and the engíneered O\¡/TS design follåws. T-he site layout and location of the 07/16118 peic test/soils evaluations are shown on the attached ptof ptan. Results of the perc test/soils evaluations are attached for reference as Appendix A' 2.0 Development of Desig¡r Parameters A soils observation trench was extended to a depth of 120" below ground surface (BGS)- There was ¡ìo evidence of ground water or high seasonal watei table in the operr excavation to a depth of 120" BGS' The soils eváuation inclicates tÍrçe distinct soil horizons underlie the site. A lithological description follows: descriotion clayey sand, red; blocky (usDA-sandy loam, blocky, moderate structure) sandy clay, tan; btocky (USDA-sandy loam, blocky, moderate structure) sandy ctaylclayey sand, tan; gravel (USDA-sandy loam, bl6cky, moderate structure, <35% rock) depth (jn.l 0"- 18" 18"-36" 36 - l2A" As based on the results from the O7t16118 site investigations (Appendix A), a design perc rate of 34 min/in. and corresponding long term acceptance rate (LTAR) of 0.50 are chosen for overall system sizing for an infilrator trl¡rch abìsorpii,rn field désigned to discharge to subsoils below the 48" depth. 2 3.0 System Design An INFILTRAIOR absorption trench is proposed for discharge of septic efflue¡t at the site. Construction of the system will consisiof excavating leuãl trenches in the area comprising the absorption field' As shown in the attached septic layout pla"n, the trenches will be oriented perpendicular.to.jl¡e natural slope to *i"¡*i"" the depth of excavatíon altng the trench length, Each trench excavation shall be continued to a rnaximum depth of 4g" BGS at the upliill side of the trench (see absorption field cross-section)' After removal of surface soils, the op"n "*tuuutions will be disked or scarified to promote subsurface absorption. Following complerion of the initial push-outs, QUICK4 STANDARD INFILTRATORS will be used to construcå sepiic effluent distribution system in the open excavations. Tbe INFILTRATOR effluent distribution system will be installed in accorda¡rce wiitr the "lnfiltrator Technical Manual", available from Infiltrator Systerns Inc., 123 Elm Street, Suite 12, Old Saybrook, Connecticut 06475' Adjacent INFILTRATORSshaII úe fastened with a minimum of four (4)314" x #8 self-tapping sheet metal or bright brass deck screws to prevent movement and separation during backfilling' Septic effluent will be transfered from the upper trench to each of the adjacent downhill trenches through a slrial distribution nefwork as shown in the attached construction details. The serial distributiorr eonnections between adjacent trenches will facilitate the saturation of the uphill trench before septic effluent is atlowed to flðw to each of the adjacent downhill trenches. As shown in the attached Absorption Field cross secrion, the bottom of the yTANDARD INFILTRATOR seepage trenches will be located a maximum of 48" bclow grourrd level. After the INFILTRATORS are insratled, synthetic filter fabric (140^200 rnesh) will be plaoed over the trenches and the system wilt be covered with a soil cap. The soil cap will consist of 36" of native soil backfill. The soil cap will be mounded 5olo above the existing ground surface to promote surface run off away from the absorPtion fields. The installer should confinn the feasibility of gravity discharge of sewage effluent from the existing septic tank to the absorption field by field verification of assumed design parameters. Assumed design parâmeters with respect to gravity discharge include: . distance from the sewage pipe at exit from the foundation to the absorption field - 100' or less, r etevation of the ground surface at errtry to the absorption field shall be no more than 18" above the invert elevation of the sewage pipe at exit from the foundation line. If field measurements do not confirm these design assumptions, gravity discharge of septic effluent from the proposed structure cannot be assured and a lift station may be required. Please contaot the design "ngin"", to address any design modifìcations necessary if these design assumptions âre not upheld. The installer must also confirm the setbacks from property lines, building envelopes, and existing easements shown in the attached graphics are maintained. Four inch clean outs shall be provided at maximum 100' intervals in all effluent lines exceeding 100' in lenglh. Vehicle traffic and parking is to be prevented over the absorption and repair area. Provide minimum schedule 40 PVC under all traffic areas Additionatly, effluent piping in traffic areas with less than 36" of cover shall be encased in 6" CMP or 3 flow fill and covered with minimum 2" high density blue board insulation. Finally, any unknown utilþ linesn easements, or pther adverse conditiois discloìed during construction must maintain the required setbacks listed on page 5 of this document. A 1,000 gallon, fwo compartment, concrete septic tank will be used to provide a minimum of 48 hours retention time for..*ugË generated from the proposed two bedroom home' A non-corrodible Orenco filter (model # FTw04ã4-io¡ ,trutt be installed af the final outlet tee of the existing septie tank or in the effluenr line berween the sepiic tank and the absorption field to limit the size of solids and sludge passing into the absorption field. Tire filter must be accessible for cleaning and replacement from the ground surface. As discussed above, INFILTRATARabsorption trenches are proposed to discharge septic effluent to the underlying sub-soils. As shown in the attached graphics, the absorption trenches will consist of three (3) trenches 3'wide x 4g" deep x 48' long with twelve (lz) srnNoARD /NF1¿TRATOR (or equivalent) units each for a total of thirty six (36tunits. The absorption field will encompass an effective area of 617,14 sq. ft. Calculations and design parameters used to size the absorption field follow. DESIGN CALCULATIONS DESIGN LOADING RATE OF 2 BEDROOMS x 150 GAL./BEDROOM-DAY:300 GAL./DAY DESIGN PERCOLATION RATE = 34 MIN./INCH DESIGN LONG TERM ACCEPTANCE RATE (LTAR) = 0.50 GAL./DAY-SQ. FT' a I.TAR'd=.WHERE, A: ABSORPTION FIELD AREA (SQ. FT.) Q= DESIGN FLOW (GAL'iDAY) LTAR: LONG TERM ACCEPTANCE RATE (GAL,/DAY.SQ. FT.) A=H= 6oo ABSORPTION FIELD AREA ADJUSTMENT FACTOR FOR GRAVITY TRENCH DESIGN: I.O ABSORPTION FIELD AREA ADruSTMENT FACTOR FOR USE OF CHAMBERS:0.7 ADJUSTED ABSORPTION FIELD AREA:600 X 1.0 X 0'7 = 420 SQ. FT' USE 36 QUICK4 STANDARD INFILTRATORS AS 3 TRENCHES OF I2 UNITS EACH CONFIGURED IN SERIAL DISTRIBUTION ABSORPTTON FIELD ADDITION SIZED AT 3 TRENCmS 3 FT. X 48 FT:432 SQ. FT. 4 4.0 Site Specific Installation/Operation Requirements The owner and system contractor shall be aware and comply with the following installation and system operation requirements' 4,1 lnstallation - Setbacks. Nqtifications. and Inspections r The system contractor must be approved and licensed by Garfield County for installation of onsite wastewater treatment systems' modifications. Installation procedures including grade, location, setbacks, septic tank size, and absorption field size shäll conform with the attached graphic details. Co¡rstruction activities and system components will not encroach upon existiñg åasements or utility comidors. A minimum of 6 ft of undisturbed soil shall be màintained between individual absorption elements and the septic tank and/or adjacent absorption elements, Minimum site specific setbacks for system oomponents are: a a Source dornestic water line domestic well domestic water cistern properry lines unoccupied structure occupied structure inigation ditch open intermittent inigation gated solid pipellined Septic Tank l0' 50' 50' 10' 5' l0' Absorotion Field 2s', I 00' I 00' l0' 5' 20' Building Sewer l0' a a 50' l0' l0' l0' 50' 2s', 25' 10' To avoid surface flow infiltration and saturation of the new absorption system, abandonment of irrigation in the vicinity of the disposal system is required. Diversio¡r ditches necessary to divert surface flows uround the new absorption bed must maintain the minimum setbacks listed above. All gravity flow sewer lines and effluent distribution piping shall be 4 inches in diameter and havã gluei joints. All lines discharging sewage from the residence to the septic tank shall maintãin fait of between l/8 in. and 1/4 in. per foot and shall employ sweep 90's or 2-45's at all turns. Sewer lines from the dwelling to the septic tank and at least 6 ft from the septic tank outlet must meet minimum standard ASTM-3034. Sewer lines under driveways shall always meet minimum Schedule 40 PVC standards. Additionally, effluent piping in traffic areas with less than 36" of cover shall be encased in 6" CMP or flow fill and covered with minimum 2" high density blue board insulation' 5 a A minimr¡m çf I 0" of soil cover ( I 8" recommended) shall be maintained over all gravity draining ISDS cornponents to prevent freezing of septic efiluent (excepting septic tank access ports which must be extended to the ground surface)' The installer shall not place the Infiltrators in the open excavation until inspected and approved by the design engineer. Additionally, the final cover shall not be placed on se\ryef tines, septiã tank, or tìre ab-sorption area until ihe system has been inspected and approved by the design engineer. The inståller shall provide 48 hour notice for all required inspections' Four inch clean outs shallbe installed at maximum 100'intervals in allgravity flow effluent lines exceeding 100' in length. A non-corrodible Ore¡co fìlter (model # FTW0444-36) shall be installed at the final outlet tee of the septic tank or in the effluent line between the septic tank and the absorption field to limit the size of solids and sludge passing into the absorptiott field. The filter must be accessible for cleaning and replacement from the ground surface' The effluent distribution system shall be constructed in accordance with the "lnfiltrator Technical Manual" availaúle frorn Infiltrator Systems lnc., 123 Elm Street, Suite 12, Old Saybrook, Connecticut 0641 5. Adjacent absorption field trenches shall be connected by a serial distribution system to assure sat-uration of the upgradient trench before effluent is passed to the adjaoent downgradient trench (see attached absorptio¡ field plan view and cross section details)' The INFILTRATORS will be coverçd with synthetic frlter fabric ( 140-200 mesh) and covered with a surf;ace cap. The surface cap shall be mounded 570 over tlre absorption field. The system contractor shall be aware of the potentiâl for construction activities to reduce soil perméabilities ât the site through compaction, stnearing, and shearing. The following þrecautions and construction pioceduies should be employed during installation to minimize disturbancc to nâtive sôils: i. Excavation shoukl proceed only when the moisture content of the soil is below tlre plastic limit. lf a sample of soil forms a rope instead of crumblirrg whurr rotlèd between the hands it is too wet a¡rd should be allowed to dry before excavation continues. ii. Excavation and backfill equipment should work from the surface where at all practical to avoid compaction of the soils at depth. iii. The bottom and sidewalls of the excavation should be left with a rough, open surface. The appearance should be that ofbroken or ripped soil as opposed to a sheared, r*e"ràà, or troweled surface. Any srnoothed or smeared surfaces should be removed with a toothed rake or shallow ripper taking care to remove loose residues from the bottom of the excavation by hand if necessary. iv. Care should be taken in placing fill materials in the excavation to avoid damaging the exposed soil surfaces. o a a a a a a 6 4.2 and a The owner shall install a structural barrier if necessary and take precautions to prevent vehicular traffic, excessive surface watering, accidental flooding, or other activities in the vicinity of the absorption field which may compact, saturate, or otherwise alter the subsurface soil parameters used in designing the septic system' The owner will ptant and maintain grass or other shallow rooted cover crop to prevent erosion and promote evapotranspiration over the absorption field' The owner will inspect and maintain the required rnounding and drainage away from the absorption field to þrevent saturation from precipitation and surfaòe flows' To mitigate the generation of preferential flow channels which may compromise the operatiJn of thelystem, the owner will inspect and prevent intrusion of burrowing animals and deep rooted plarrts into the absorption field. The septic effluent filter shall.be inspected and cleaned as rìecessary every six (6) months. The owner will conduct periodic maintenance of the septic system by removing accumulated sludge from the septic tank every 3-4 years to prevent clogging ofthe absorption field' a a a a a 7 5.0 Limitations This report is a site specific design for installation of an onsite wastewater treatment system and is applica'ble only t'or the client tbr whorn our work was performed. Use of this report under other' .irrurortancesis not an appropriate application of this document. This report is a product of CCI Engineering/Cronk Construction Incorporated and is to be taken in its entirety. Excerpts from this report ru-y b. takãn out of context and may not convey the true intent of the report. lt is the owner's and owner's agent,s responsibility to read this report and become familiar with the recommendations and design guidel ines contained herein. The recommendations and design guidelines outlined in this report are based on: I ) the proposed site development and plot plan as furnished to CCI EngineerirrglCronk Cotistruction Incorporated by the client,'and2)the site conditions disclosed at the specific time of the site investigation of reference. CCI Engineering/Cronk Construction Incorporated assumes no liability for the accuracy or completeness of infórmatiou furnished by the client. Site conditions are subject to external environmental effects and may change over time. Use of this plan under different site conditions is inappropriate. If it becomes apparent that current site conditions valy from those anticipated, the design engineer should be contacted to develop any required desigrt r¡odifications. CCI Engineerirrg/Cronk Construction Incorporated is not responsible and accepts no liability for any variation in assumed design parameters' CCI Engineering/Cronk Construction lncorporated represents this report has been prepared within the Iirnits piescribed by the owner and in accordance with the currertt accepted practice of the engineering profesiion in the aiea. No warrant¡r or representatiou either expressed or implied is included or intended in this report or in any of our contracts. J-.r-rl' L N graphics including: 1) plot pla absorption field cross section. graphics. In additiono results reference as Appendix A. Thomas A.Cronk, P.E. Date 'disposal plan is meant to include the following four pages of n,2) septic layout plan,3) absorption field plan view, and 4) The plan is not to be implemented in the absence of these related from the percolation test and soils evaluation are included for I r3?7.6?', N89'51',04',Vûccess eûsenentPerc testexcqvûtion,tvp'shopresidenceHoty Cross UndergroundRDV eqsenentsoits obserexcûvûtlon\on)iÞazoo0n)\"q\663,50', sB8'4r'46',Esee exPondedvlew oboveT¡JÕrurUooØoq\o(n\oûJû)p(D-.tt/,oo{¡)(,of'lHtT-LAND PRBJEIT348 SHNSHONE DRIVEI,tû179-e3e-01-003PLANY 16, e018NBRTHl'=?00'I\tf\ -,.\_/8?.7 ocres ße7a2' N89"51',04'V\\II\\\III\\I\IIII\\Nt]TECALL S11 FOR UTILITY LI]CATESe xco,votioñ,typ'solls DbservûtlohexcqvttionûbEorDtbn F¡etd conslstìng of 3"ó"r br 12 ouick4 InfittrutorsiJ" -.oritote"t) for o totoL ofàZ ""itt configured ìn serioldlstribution ¡s shownHoty Eross Undergnound -RüW eûsenen-!gOçÇpercootlon septic tonkFtuent fltter (USl\,Ð\o^crÊs \-*/eÎModet FTV0444-36)82.7 aIIIIIIILNOTEPRÛVIDE 4' CLEAN BUTS_AT MAXIMUMió-o;-rñrEBvnus iN ALL EFFLUENTi¡¡rei :,rcEeuNG 1oo' iN LENGTHshoPNOTEÍ:PÀVÌTY DISCHARGE OF SEVAGEËÊliúrnr FRBM THE RESIDENcEio îur DISPnSAL sYsrEM lsàÃssD-oñ 1HÈ FoLLovING DESIcNASSUMPTIT]NS:I FNGTH OF SEVAGE P]PIN6FBbn rxtr AT FEUNDATIDNLiñt ro ENTRY ro ABSURPTIDNFIELD = 100' ßR LESSrI FVATION OF GRDUNN SURFACEii-iuipi ro ABSBRPTIoN FIELD'¡in rliiee IHAN 18' ABovE INVERTËftvÀrlo¡r oF SEVAGE PIPE ATËltr rBorq FoUNDATioN LINEDiSCLATMER.IF ÏHESE DESIGN ASSUMPT]ONS AREünr' u-pntr-b DURING coNSTRUcrIoN'äñÁvrrV-o¡scHARGE cAN Nor BEÃiïúnen Ãñ¡ n llrr srATIoN MAYBE REOUIREDSEPT]C LAYBUTJULY EO, EO18+ùNBRTHPLANPROJECTSHI]SHONE DR]VT-0031'=40'NOTETHE FBLLDVING SETBACKS MUST BE MAINTAINID:SEPT]C ASSI]RPTTONSPRINGS,/VELLS - 50'inxEzs lBt,qMzIRRIG. DITcH - 50'IN'TERT'IITTENT IRRIG, DTTCH- 10'100'50'z5'e5'l0'100'e5'20'10'DOMESTIC ì,/ATER CISTERDOMESTIC VATER LINEECCUPIED STRUCTURI -.-_- l0'UNf]CCUPIED STRUCTIJREPRUPERTY LINE -- l0¡FIELDTANK,/LINED DITCH -l0'l0'GATE! P]PESDLIÛ PIPEdrlveresidenceon out oo 2' preferred)o- oo oo septic inftuent thnee (3) rows oF twetve (l?) QUICK4 STANIARÐ INFILTRAIOR units for o totat of thlrty slx (36) units configured in seríot distribution qs shown t 4B"typ. 36'tyP. { seriût d¡strlbutlon configurotion, otternqte end-to-end, provide inspect¡on/venting ponts ät eoch end of infittrotor trenchcs ag showñ ABSSRPTII]N FIELD _ PLAN VIEV SCALE¡ 1'=?0' 4' SCHD 40 PVC VENT/INSPECTIEN PROJECT SHT]SHNNE DRIVE -e3e-01*003 ABSORPTION FITLD - PLAN VIEV JULY ?0, ?018 SCALE¡ l'=?0' l SERIAL DISTRIBUTIEN INLET - USE HIGH KNDCKDUT, (END IIR SIDE) PORT SBIL CAP SERIAL DISTRIBUTION CONNECTION DETAIL SCALE:1/2"=1' SERIAL DISTRiBUTIT]N I]UTLET - USE H16H KNOCKT]UT, TYPICAL (END T]R SIDE) s1â?llnûx. 3/1 (332) Etopesolt coP, Provldenin, 5Z drtinqgehin soe c t ionlv e ntingut each end of intrenchpontf ittrûtor-18',5Þta-ie0'SUILS Lo6(SEE NNTES)exlsting gnound surfoceb(.,I\\III6'nin.(10'-18' Preferreol)OUICK4 INFILTRATT]R,with 'INFILTRATIIR Tdiskor scoriFy undereôchiñFitt.ttor trenchinstolt¡n ùccordôñce36',*1ECHNICALMANUALûvoitùbtefrom InfittrotorSystensre, Btdlnc., 123 EtnStreet, SuiteSaybrook, Connâcticut 06475typ¡cûtlnf l{trûtÕr tnenchcrosSsection(onÊ of three)ABSI]RPTII]N FIELD _ CRI]SS SECTII]N (TYP' THREE T]F THREE)SCALE, 1'=5'HOLLAND PROJECT348 SHNSHONE DR]VEîi.tffiÎoRiP,?t'D - cRBSs s'crioNJULY 20, 2OI8SCALE¡ 1'=5'ot-[T*ooot]3J*tJrt$oo,i.ttoff Ir,MûD'RATESTRU.T'RE)ot-l:H#Siori"rttff;"ltrïT.t*y.M-DDEBe'lE-:TRUCTURE)-'ìÌßç'-tï"i"':ïY":'$J"&":iP.#åli"!?.¿5l',*.( 352 R0cK)FP NR HI6H SEASDNAL VATER-ärInw ERoUND suRFAcENÛ GRTUNDVATTABLE TÛ iEO'SI]ILS LO6 NOTESIFICATI[NSELEVATII]N IESIGN SPÉC100.00'96.50',85',AREA98.69'AREAAREA98,e0'96.00'TMENIALINERETMENT.TANK!tïAREATiI]NTREATMENTTREANTSOILANKDUNDATTNTMESTILFSEPTICSBTLRYOMTBTREAFR0t,lFRNMFRENTSEPTICTRYTSOILATI]EXIfEXTTEXITENuFCETTTAINEAAALACENENEINEANKSURTLLIURFSIVEGRBUNDFOUNÐATTBNSEPTiCSEVA6ESEVAGESEVAGE0¡TRATuFctFNFFROMFRI]I'I]NINFlLANCEANCEEFEVAEVATiI]NSTELEVATIiINlSIELEVATIELD!III]NATUI.IEDs¡6NLENVERTDESJ6NASSEINVERTINVERÏDE APPENDIX A SOruS AND PERCOLATION REPORT CCI ENGINEERING/CRONK CONSTRUCTION INCORPORA'I'$D I @ Cq ENGINEERING ll29 -24- Road Grand Junctionr GO 81505Cronk Gonetructlon lnc. Grand Junction (970) 245-0577' Glenwood SpringVAspen (970) 640-5029'Montrose/Delta (970) 640-s029 Email: ccigj@msn'com SOILS AND PERCOLATION REPORT July 16, 2018 Thomas A. Cronk, P.E. I129 -24- Road Grand Junction, CO 81505 970-245-0577 Bill & Renee Holland 348 Shoshone Drive silr, co 81652 970-379-4969 348 Shoshone Drive, Silt, CO 81652 2179-232-01-003 depth (in.)des.cription clayey sand, red; blocky (USDA-sandy loam, blocky, moderate structure) sandy clay, tan; blocky (USDA-sandy loam, blocky, moderate structure) sandy clay/clayey sand, tan; gravel (USDA-sandy loam, blocky, moderate structure, <35% rock) 0" _ 18" l8'-36" 36' - 120" Date: Prepared by Client: Property address: Tax schedule No.: LegalDescript.; 1.0 Soils Evaluation The site consists of approxim ately 82.7 acres of uncultivated native soil. Drainage is approximately l5% to the northwest in thJarea of concern. A percolation teslsoils evaluation was conducted on the propefy of rcfçrçnce on 0':7116118 bv Tom A. Cronk, registered professional engineer (R.P.E.). The perc excavation trenches were located approximately 75' southwest of the existing shop. A soils observation trench was extended to a depth of 120" below ground surface (BGS). There was no evidence of ground water or high seasonal water table in the open excavation to a depth of 120" BGS. The soils evãluation indicates three distinct soil horizons underlie the site. A lithological description follows: 10 Perc holes were constructed in excavations A, B and C at depths of approxirnately 36 in' The holes appeared to be well saturated at the time of the test. Results of the percolation test are shown in Table l. TABLE 1 2.0 SEAL Thomas A Cronk, P.E. This document is representative of the site conditio¡ts disclosed at the specific time of the site investigation. Site óonditions are subject to ctrange from external events both manmade (irrigation or water featurc construction) and naturãlly occurring (flooding or excessive precipitation). ccl engin"ering/Cronk Constiuction Incorporated is not responsible and accepts no liability for any future variation in site conditiolts. CCI Engineering/Cronk Construction Incorporated represents this report has been prepared within the limits piescribeã by the owner and in accordance wittr the current accepted practice of.the civil *.r,gi,,.*ring profession in the area. No warranty or representation either expressed or implied is included or intended in this repoú or in any ofour contracts' B Date{ Percolation Tesl Results 07ü6ll Perc Rate Time Drop I l:34l0:34 I l:04 Depth 34601t.153.25- 48" 2775.036" - t7I9.s0- 48" l1