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HomeMy WebLinkAboutSubsurface Investigation & OWTS Design Report.pdf' , AL • 3 Four Wheel Drive Rd Carbondale, CO 81623 970·309·5259 ~rn~1~1 ~ , ' ~ July 14, 2014 Larry Singer lssinqer@comcast.net Project No. C 1072 Subsurface Investigation and Onsite Wastewater Treatment System Design 2621 CR 100 Garfield County, Colorado Larry, ALL SERVICE septic, LLC performed a subsurface investigation and onsite wastewater treatment system (OWTS) design for the subject property. The property is located outside of Carbondale, in an area where OWTSs and wells are necessary. The property is in the process of being redeveloped to add to the main residence and construct an auxiliary building which will include plumbing . SITE CONDITIONS A 3-bedroom, single-family residence and one bedroom cabin presently exist and are utilizing an ex isting OWTS . There is a desire to upgrade the existing OWTS and incorporate an addition to the residence , which includes 2 bedrooms , and a future greenhouse/RV pa rking structure with plumbing. The existing OWTS will be abandoned. There is a private well located on the property. Minimum regulatory setbacks will be maintained to pertinent physical features such as the private well , the Roaring Fork River, and auxiliary ditches . The subject property is located within the floodplain . SUBSURFACE Native Soils: Sampling of the native material was taken from the Soi l Profile Test Pit located on the southwest portion of the property. The subsurface was investigated on April 17, 2014 by digging one 6.5 -foot profile pit and taking a soil sample from approximately 2 to 3-feet below grade . A gradation analysis and hydrometer analysis was run by HP Geotech and results are detailed in a report dated April 23, 2014, Job No 114 021E. The materials encountered in the test pit consisted of 2.0-feet dark brown , dense, moist root zone, underlain brown gravelly sand with 4 to 6-inch cobbles to a maximum depth explored of 6 .5-feet where groundwater was encountered . The bottom of the pit exposed larger cobbles up to 18-inches in d iameter. The gradation performed by HP Geotech shows the soil consists of 54 % gravel , 39% sand , and 7% silt and clay. The USDA soil type is classified as Very Gravelly Sand . The gravel percentage in this soil deems the soil unsuitable for treatment of wastewater. '. Page2 Groundwater was monitored after ditches were turned on May 5, 2014. Groundwater was recorded in the profile pit at 5.5-feet on May 6, 2014, at 4.5-feet on May 15, 2014, and at 3.5-feet below grade on May 30, 2014. For purposes of this design, we will estimate high groundwater level at 2- feet below grade. Imported Fill: The proposed soil treatment area (STA) will be a mound system with imported soil, building the Infiltrative area up 4-feet above natural grade. Fill for the mound system was tested by Kordziel Engineering, Inc. and consists of 11% gravel, 48% sand, and 41% fines at 2-feet below grade with a description of sand, silty, slightly clayey. The sample obtained at 6-feet below grade consists of 22% gravel, 39% sand, and 39% fines with a description of sand, silty, clayey. 2-feet of sand filter material will be the primary filter material. The imported soil is the most limiting horizon; therefore, the system will be sized using a long term acceptance rate (L TAR) of 0.9 gallons per square foot in accordance with Table 10-1 Soil Type 2 and Treatment Level 2 presented in the Garfield County On-Site Wastewater Treatment System Regulations, adopted April 14, 2014. DESIGN CALCULATIONS 3 bedrooms x 75 gallons/person/day x 2 people/bedroom = 450 gallons Residence 2 additional bedrooms x 75 gallons/person/day x 1 person/bedroom= 150 gallons Residence 1 bedroom x 75 gallons/person/day x 2 people/bedroom = 150 gallons Cabin Future greenhouse/RV parking structure to be used by residents Wastewater flow = 750 = Q Septic Tank sizing for 6 bedrooms = 1750 gallons minimum Soil Type = Sand = 1.25 gallons/ SF I day Soil Type Imported Material = Loamy Sand = 0.9 gallons/ SF I day (limiting horizon) Soil Type Basal Area = Unsuitable Soil Treatment Area = 833 SF Pressure dosed bed 833 x 1.0 = 833 SF Pipe and gravel bed = 833 SF x 1.0 = 833 SF Approximate footprint of infiltrative area = 15' x 56' Height of mound = 4' fill material + 2' sand filter material + 1' pipe and gravel + 1' topsoil = 8 ft Approximate footprint of basal area of mound based on height to infiltrative area of 7' = 36' x 77' The installation will include two 1000-gallon septic tanks with a pumping system in the second compartment of the second septic tank. Effluent will be pumped to a 15' x 56' sand filter STA 2-feet in depth, mounded over 4-feet of imported fill and incorporated into an extension of an existing benm. The sand filter will be pressure dosed. 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 0.25 and 0.60 mm. The uniformity coefficient must be 4.0 or less. Material meeting ASTM 33, for concrete sand, with one percent or less fines passing 200 mesh sieve may be used. Pipes used to disperse the effluent must be surrounded by washed coarse screened gravel or crushed stone. All of the gravel or stone must pass a 2 %-inch screen and must be retained on a %-inch screen. ' ' Page 3 Grades will need to be shot with the contractor prior to installation of the system to determine depth of the septic tank burial and proper specifications of the pumping system. 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. FLOODPLAIN CONSIDERATIONS To ensure no infiltration of flood waters into the OWTS, septic tanks will be installed in accordance with manufacturers' recommendations and appropriately seam-sealed. If groundwater levels are higher than 2-feet below grade, and burial depth exceeds 2-feet, an H-20 rated lid will be specified. Additionally, PVC risers and water-tight lids will be specified. Septic tanks will be anchored to assure they do not float. The STA will be mounded 4-feet above native grade with the imported silty, slightly clayey sand described above. The STA will consist of a pressurized sand filter system will be an extension of the existing berm located in a drier portion of the property, east of where the profile pit was excavated. The mound design will incorporate the minimum final slope no greater than 3-feet horizontal to one foot vertical. 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. Loading from ' . Page4 a water softener should not be discharged into the OWTS . No hazardous wastes should be directed into the OWfS. Mechanical room drains should not discharge into the OWfS. The OWfS 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 ex isting 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 OWfS during construction . The OWfS 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 accord ing 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, ALL SERVICE septic, LLC Carla Ostberg , MPH , REHS Reviewed By: ~-~~ ') \~ ~~ ). Liability Clause : Under no circ um sta nces wha ts oe ver shall th e lia bility of ALL SERVICE septic, LLC, in connection with any contra ct, directly or indir ectly, exceed th e to tal amount p aid by th e client to ALL S E RVICE septic, LLC for the services an d/or goods whic h are th e s ubject o f th e contract in c onnection with whic h the liability arises. N ~ ~ O' 25' 50' Scale: 1• = 50'-0" Hll ~mri~ ------------I ,. .......... ·· 33 Four Wheel Drive Road Caltlondale, co 81623 970.309.5259 APPROX. LOCATION OF NEIGHBOR"S WELL 0 Tc ..,_,.. ..,. ·~ ROARING FORK (i) SITE PLAN I &SP Singer Res idence 2621 CR1 00 Gar1leld County. Colo<ado Project Number. C1072 -- / / / .,,,·· ,,,.· ..,,,.·4"""" .,··"·· ·" ·'' .·"' / .. /· --- --- !Date: 07/14/14 Deelgned By: CBO I w 1 . 0 ReviewedBy. RHP !Drawn By: ANG s~ 1 of 4 N ~ ~ O' 15' 30' Scale: 1" = 30'-0" /··"" / / / ...... /~DON EXISTI / SEPTICTANKAN / ABSORPTION r-- I I I ,__ ( .-,-j (2) 2" DIA PUMP ...... .;::..--I I ,/ LINES -~·-__ .,,.·. , .. ---·· ,,,,..· ,,,,. ....... SOIL PROFILE TEST ~ 1'1. PIT ANO L:.-,1' GROUNDWATER MONITORING LOCATION PROPOSED RV PARKING ANO GREENHOUSE /..... :r ..... / I ._, i I I -:.... (i') owrs DESIGN Hll ~m"~ 33 Four Wheel Drive Road Carbondale, co 81623 970.309.5259 S inger Residence 2621CR100 Garfield County, Colorado Project Number: c1on ·"" Data: 07I01/14 Designed By: CBO I W2. 0 OraMI By: ANG I Si-t 1 of 4 PATIALLY MOUNDED DRAIN FIELD CROSS SECTlON • TYP. 4" PVC OBSERVATION PIPE PLACED IN 8" ROUND SPRINKLER BOX 2:1 SLOPE FOR SA.ND----~ 3:1 SLOPETO NATURAL GRADE 8' NOTE: SAND SPEC 100% PASSING NO. 4 SIEVE, EFFECTIVE SIZE BETWEEN 0.25 AND 0.6 MIN. UNIFORMLY COEFFICIENT SHALL BE 4.0 OR LESS 1.5" DIA SCH-40-----+~ PERFORATED LATERALS WITH 5132" HOLES 4' ON CENTER FACING DOWN OBSERVATION PIPEc, ---i~ TYP. 2 AT EACH BED IN OPPOSITE CORNERS 36' EXTENT OF MOUND-......... ,..--GEO·FABRIC " 15'------.,Y SURFACE OF MOUND 12" DEEP PIPE AND GRAVEL BED (2" COVER OVER PIPES) 3/4"TO 2112" SCREENED GRAVEL 1 . ~· TOPSOIL ~~ 1.5"PIPEWITH5/32~0RIFICE -... -·: · · ..... o . , ··~,.~\ 1, HOLESFACINGDOWNAT4' 4. ··· .t · -: ·· · ,_. . . ON CENTER. PIPES SPACED CONCRETE ·SAND 4.5' ON CENTER 4' IMPORTED FILTER MATERIAL SCARIFY SURFACE GROUNDWATER AT 2.0 FEET SHOOT GRADES WITH EXCAVATOR FOR PUMP SPECIFICATION (2) 2" DIA SCH-40 PUMP LINE FROM TANK PLAN VIEW· TYP. ~ ,;; 'Z I 3' 0 4.5'0.C. 4.5'0.C. 3' 0-----------56'----------i NATURAL GRADE 15' ~ ,;; 0---------------77'--------------i H l l ks.eent tii~ ~mfl~W 33 Four Wheel Drive Road Carbondale. co 81623 970.309.5259 (3)PIPE AND GRAVEL ~OUND D~~I~ Singer Residence 2621CR100 Garfield County, Colorado Project Number: C1072 Date: 07N4/14 Designed By: CBO Reviewed By: RHP Drawn By: ANG W3.0 Sheet 3of4 DESIGN 3-BEDROOM RESIDENCE+ 2 FUTURE BEDROOMS 1·BEDROOM CABIN (75 GAUPERSONIDAY x 2 PERSONS/BEDROOM x 3 BEDROOMS RESIDENCE) (75GAL/PERSON/DAYX1 PERSONS/BEDROOM X 2 BEDROOMS RESIDENCE) (75 GALJPERSONIDAY X 2 PERSONS/BEDROOM X 1 BEDROOM CABIN) WASTEWATER FLOW= 750 GALLONS TANK: 6 BEDROOMS = 1750 GALLONS 1000-GALLON, SIJ.IGLE-COMPARlMENT TANK FOLLOWED BY 1000-GAU.ON, TWO-COMPARTMENT TANK WITH PUMP SOIL TREATMENT AREA (STA~ LONG TERM ACCEPTANCE RATE (LTAR) Z SANO FILTER= 1.25 GAl.J SQ FT (TL2) L TAR4' IMPORTEO MATERIAL= 0.9 GAlJSQ Fr (n2) L TAR BASAL AREA= NOT SUITABLE 4' IMPORTED SOIL (MOST UMmNG) = 0.9 GAlJ SQ Fr 750 GAL x 0.9 GAU SF= 833 SF 15' X56'SAND FILTER 36' X 77' BASAL AREA DO NOT GLUE FINISHEOGRAD7 ~SLIP-ON PVC CAP ~~ ,!;~E':._, a (EFFLUENTLINE ...,,----.-, .J}/ II 'W TO HOUSE TOTMI< © Cl£ANOUT DETOJheEAl INSULATED COPPER TRACER WIRE 1000-Gallon, Single -Compartment Septic Tank, Add Effluent Filter to Outlet Tee 1000-Gallon, Two -Compartment, Effluent Pumping Tank Inlet Tee H ll ~entid ~m1~¥v Canente R11n wllll Ude _ ..... /waf Fram R'mers _L rJ ...,~ ... ""' (5\ TANK OEJAIL "" "'000 33 Four Wheel Drive Road Csrbondale, CO 81623 970.309.5259 ~f99 Of'OOtW. -ADD EFFUOT AllER TO ""',,, """"' """""'"' .... _ .. """"'""' ~~Uclwlh ~~==~ •---'""'====---,-.,..'""''-., / nlCOlllll'lended adhelM) W j/ V.r---Oilctlorvl~ ..... H_ ~-· , ...... ~ '"";:""-~11F>9b ~"~ I -~ :'1'! .. ,. Ut=:::::'"""- Singer Residence 2621 CR100 Garliald County, Colorado Praject Number. C1072 (6) TANK DETAIL '"'"™ --.. Chock \laMi (optioncll) _ ...... _ a.i+------"" ~----s-.ied Pmip V..ll l'lclr;ed on ConcfWhl llao:lt Date: 07114114 Designed By: CBO Reviewed By: RHP Drawn By: ANG W4.0 Sheet4 of4 ... HJ Ge<!> tee H F PWORTH -PAWI AK G E'OTFCHN I CA I IN G A pr il 23 , 20 14 CBO In c. Attn : Ca rl a Ostberg 33 Four Whee l Driv e Road Carbondal e, Co lorado 81623 ~ m I :L_Ylil be rg(!fa.ill rn i I.c om llq11wllh 1·.m l.11, Cr'''" 11111<.d Im ll'h ( O•f•i•v 11., ,d l ~ l ( rlt 11 1.\ nod 'J'' rn g~. ( ' IPr.11 111 :, If,') I l1 h10 w 1170 'l l 'i 7'!>'~ I "· •1 fl 11 ·, 15 I I 111 .1 d l 1Jt\'' t 1't1 1l p .·1·r11t~ n '·"'H Job No. 11 4 02 JE S ubj ec t: Laboratory Test Re sult s, 2621 100 Road , Gu rfi elcl Co unty, Colorado Dea r Mr s. Os tberg : As requ es ted , Hepworth-Pawlak Geo tec hni ca l, In c. pe rform ed gradation analys is on a sa mpl e de liv ered to our labora to ry by you . The se rvices were perform ed in accordance w ith our agree ment fo r profess ional e ng in ee rin g serv ices to yo u , dated Janua ry 24, 20 14. Re sult s of the gradat io n and hydrometer analysi s perform ed on th e sa mpl e a re pre se n ted o n F igure I. Th e sample tes ted has an USDA Soi l Tex ture C lassifica ti on of Very Grave ll y Sa nd. If yo u have any qu es ti o ns or need further ass is ta nce, plea se ca ll o ur office. S in cere ly, -PAWLAK GEOTECI-IN ICAL, IN C. Loui s E. Ell er LEE /ksw a tt ac hm e nt F ig ure I -USDA Soi l Text ur e Gra dation Test Result s 1'11 r im · 30.S-H..i 1-7 11 1) • < 'o lo ra ti o S p r i 11 g ~ 7 1 1>-<JJJ -~ SC. 2 · S i I \'l' 1· 111 o rn<· 1'7 0 -·168 -1 98 1> '' ' I HYDROMETER ANALYSIS I SIEVE ANALYSIS I 24 \ . 7HR TIME READINGS 1 MIN.I O 45 ~fu. 15 MIN. 60M1Nl9MIN.4 MIN. #325 #140 U.S. STANDARD SERIES I #60 #35 #18 #10 #4 CLEAR SQUARE OPENINGS \ 3/6' 3/4' 1 1/2' 3' 5'6' 8' 100 10 90 20 80 30 70 0 60 Cl w 40 z z Iii < Vl .... <( w n. 0:: 50 .... .... 50 z z w w 0 0 0:: ffi w 40 n. n. 60 70 30 80 20 90 10 100 0 .001 .002 .005 .009 .Q19 .045 .106 ,025 .500 1,00 2.00 4.75 9.5 19.0 37.5 76,2 152 203 DIAMETER OF PARTICLES IN MIWMETERS ClAY I OLT I v. ANE I FINE I = !COAASE j\l.COAASEI SMAU I MEOIUM I !.ARGE I COBSl.ES GRAVEL 54 % SAND 39 % SILT AND CLAY 7 % USDA SOIL TYPE: Very Gravelly Sand FROM: 2621 100 ROAD 114021E ~ H"""worth-Pawfak Geotec;lmlccl USDA GRADATION TEST RESULTS Figure 1 ... 100 .0 90.0 80.0 70.0 ~ 60.0 ;;; ., &: 50.0 1:! 8 .. &: 40.0 30 .0 20 .0 10.0 0.0 o.oi KORDZIEL ENGINEERING, INC. Gradation Test Results #200 #100 #50 #30 #16 #8 #4 3/8" 314" 1-112" 3• )1 ,., ~~ "'' _,,J f"' ,, ~r ~ j~ v I _/ : I ' 0.1 10 Diameter of Particle In Millimeters DESCRIPTION : Sand, silty, sli g htly clayey (SM -SC) GRAVEL 11 % HOLE I SAMPLE P-1 SAND 48 % DEPTH 2' FINES 41 % LIQUID LIMIT MOISTURE 6.2% PLASTICITY INDEX DRY DENSITY (pct) NIA DA T E: 3/29/2013 NAME : 1422 W. Buttermilk Road 0 JO 20 30 40 50 60 70 80 90 100 100 PROJECT NO.: 1462 FIGURE! . . ' ~ 100 .0 90 .0 80 .0 70 .0 ff 60.0 ~ 50.0 = .. u .. .. 40.0 ~ 30.0 20.0 10.0 0 .0 0 .01 KORDZIEL ENGINEERING, INC. Gradation Test Results #200 #100 #50 #30 #16 #8 #4 3/8" 3/4" 1-112" 3" ~ , J' I ~,... ....... ~ ~ ~ ~t .... '/ ~ .... v" ' 0.1 10 Diameter of Particle in Millimeters DESCRIPTION:Sand, s ilty, clayey, gravelly (SM-SC) GRAVEL SAND FINES 22% 39% 39% MOISTURE 8.1 % DATE: 3/29/2013 NAME: 1422 W. Buttermilk Road HOLE I SAMPLE DEPTH LIQUID LIMIT Profile 6' PLASTICITY IND EX DRY DE NSITY (pct) NIA 0 10 20 30 40 50 60 70 80 90 100 100 PROJ ECT NO .: 1462 F1GURE2