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HomeMy WebLinkAboutOWTS Design Report 05.07.2014ALL sEgyIcI 33 Four Wheel Drive Rd Carbondale, CO 81623 970-309-5259 May 7, 2014 Project No. C1076 Fran Niccoli 2074 CR 109 Glenwood Springs, CO 81601 Subsurface Investigation and Onsite Wastewater Treatment System Design 5 -Bedroom Residence 2074 CR 109 Garfield County, Colorado Fran, 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 Glenwood Springs, in an area where OWTSs are necessary. SITE CONDITIONS A 5 -bedroom, single-family residence presently exists and is utilizing an existing OWTS. The existing system is experiencing problems. After some investigation, the existing distribution box was uncovered and was found to have no lid. The first gravelless chambers in the trenches were found to have standing water and the chambers appear to be at least 6 -feet below grade, which is not desirable. Rather than attempt to repair the existing system, a new, upgraded system is preferred. There is a separate, existing OWTS that serves the additional dwelling unit (ADU) on the property. This system is not experiencing problems and will remain in place. The subject property is served by a community water system managed by the Teller Springs Homeowner's Association. The well is located approximately '/4 mile from the subject property. A dry gulch runs to the east and north of the residence. A 25 -foot setback must be maintained from the dry gulch to the proposed absorption area. SUBSURFACE The subsurface was investigated on April 23, 2014 by digging one 8 -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 28 2014, Job No 114 021F. The materials encountered in the profile pit consisted of 6 -inches of topsoil underlain by light brown, granular gravelly, silty sand with cobbles from 2 to 4 -inches in diameter to 4 -feet, underlain by light brown, granular gravelly, silty sand with cobbles from 4 to 6 -inches in diameter and some large cobbles Page 2 to a maximum depth explored of 8.0 -feet. No bedrock or groundwater was encountered. The gradation performed by HP Geotech shows the soil consists of 35% gravel, 42% sand, 23% silt and clay. The USDA soil type is classified as Very Gravelly Sandy Loam. A long term acceptance rate (LTAR) of 1.0 gallons per square foot will be used to design the OWTS. Profile Pit Excavation (Observed April 23, 2014) View of profile pit excavation 8 -foot profile pit — cobbles View of pit location looking southeast View of profile pit backfill View of proposed area looking northeast DESIGN SPECIFICATIONS The OWTS design is based on 5 -bedrooms. An average daily wastewater flow of 750 GPD will be used. The system will utilize the existing 1500 -gallon, two-compartment septic tank. An Orenco® Page 3 effluent filter must be installed on the outlet tee of the septic tank. The existing pipe exiting the septic tank is approximately 4 -feet below grade. There must be a minimum 1% grade from the septic tank outlet to the new distribution box. This minimum grading must be considered in order to minimize coverage of the new gravelless chambers. The proposed absorption area should be cited as far north on the property as feasible. A new distribution box, baffled and accessible from grade, must be installed. Effluent will be distributed to four rows of gravelless chambers, each with 14 Biodiffuser® ADS ARC 36 chambers to obtain the required 675 square footage in a bed configuration. Six inches of concrete sand should be placed below the chambers for additional treatment due to cobbled soils. Maximum cover over the chambers should not exceed 2 -feet of uniform, granular with no material greater than minus 3 - inch. OPTION: While trenches are the most desirable design alternative, the cobbled soils may not allow for stable sidewalls during excavation. If trenches are feasible, 563 square feet is required. This can be obtained with the installation of three rows of 16 Biodiffuser® ADS ARC 36 chambers. There must be at least 6 -feet of undisturbed soil between each trench. Six inches of concrete sand should be placed below the chambers for additional treatment. 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 Sewage Disposal Regulations, the Individual Sewage Disposal (ISDS) Permit provided by Garfield County Building Department, and this design. 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 an absorption area. Page 4 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 should be installed to allow pump lines to drain to minimize risk of freezing. Excavation equipment must not drive in excavation of the absorption area 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 absorption area 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 installer should have documented and demonstrated knowledge of the requirements and regulations of the county in which they are working. Please call with questions. Sincerely, ALL SERVICE septic, LLC . Crx O -.g Carla Ostberg, MPH, REHS Reviewed By: GeS1-1 tech NEPWORTH-PAWLAK GECTECI4NICAL INC April 28, 2014 CBO Inc. Attn: Carla Ostberg 33 Four Wheel Drive Road Carbondale, Colorado 81623 carla.ostbergla ginai€.con Hepworth-Pawlak Geotechnical, lnc. 5020 County Road 154 Glenwood Springs, Colorado 81601 Phone: 970-945-7988 Fax: 970-945-8454 !;mail: hpgeo(alhpgeoteeh.com Job No. 114 021F Subject: Laboratory Test Results, 2074 109 Road, Garfield County, Colorado Dear Mrs. Ostberg: As requested, Hepworth-Pawlak Geotechnical, Inc. performed gradation analysis on a sample delivered to our laboratory by you. The services were performed in accordance with our agreement for professional engineering services to you, dated January 24, 2014. Results of the gradation and hydrometer analysis performed on the sample are presentcd on Figure 1. The sample tested has an USDA Soil Texture Classification of Very Gravelly Sandy Loam. If you have any questions or need further assistance, please call our office. Sincerely, HEPWORTH — PAWLAK GEOTECHNICAL, INC. Louis E. Eller LEE/ksw attachment Figure 1 — USDA Soil Texture Gradation Test Results Parker 303-841-7119 • Colorado Springs 719-633-5562 • Silverthorne 970-468-1989 HYDROMETER ANALYSIS TIME READINGS 24 HR. 7 HR 1 MIN. 0 45 MIN 15 MIN. 60MIN19MIN.4 MIN #325 10 20 30 40 50 60 70 80 90 100 SIEVE ANALYSIS U.S STANDARD SERIES CLEAR SQUARE OPENINGS #140 #60 #35 #18 #10 #4 3/8" 3/4" 11/2" 3" 5"6" 8' 100 3 11,110103 1 • r { 1 001 .002 CLAY .005 .009 .019 045 106 1 025 .500 1 00 2.00 DIAMETER OF PARTICLES IN MILLIMETERS sn r 'i!'NC v. EINE J 51NF { 3.1F0IUM I CLIANSEN CaABSE GRAVEL 35 % SAND 42 % USDA SOIL TYPE: Very Gravelly Sandy Loam 475 95 19 0 37.5 76.2 152 203 viva `.71.1111 1 N{I]II,M i iA1i[Y.. SILT AND CLAY 23 % COBBLES FROM: 2074 County Road 109 90 80 70 60 50 40 30 20 10 0 .c, N Scale: Not to Scale COUNTY ROAD 109 THE LOCATION OF EXISTING AND PROPOSED IMPROVEMENTS SHOWN ARE NOT THE RESULT OF A PROPERTY SURVEY. THE LOCATIONS ARE APPROXIMATE. IT IS THE HOMEOWNERS DUTY TO ENSURE ALL CONSTRUCTION AND IMPROVEMENTS LOCATIONS ARE ACCURATE. ALL SETBACK DISTANCES SHOULD BE CONFIRMED PRIOR TO EXCAVATION. PROPERTY LINE _ n SITE PLAN MOT TO SCALE 5 -BEDROOM RESIDENCE -u�CH /97"Ekf. F DRAWINGS MUST BE USED IN CONJUNCTION WITH DESIGN LETTER DATED 5/07/14 33 Four Wheel Drive Road Carbondale, CO 81623 970.309.5259 Niccoli Residence 2074 CR 109 Garfield County, Colorado Project Number: C1076 Date: 05/07/14 Designed By: CBO Reviewed By: RHP Drawn By: ANG W1.0 Sheet 1 of 6 - rN 0' 15' 30' Scale: 1" = 30'-0" BARN EXISTING 1500 -GALLON, TWO-COMPARTMENT SEPTIC TANK TO REMAIN -- 5 -BEDROOM RESIDENCE ()PROPOSED OWTS 30 - 0 o EXISTING 1000 -GALLON PLASTIC TANK TO REMAIN EXISTING 414 SF INFILTRATOR CHAMBER ABSORPTION AREA TO REMAIN (ISDS PERMIT 2002) 1 7 DISTRIBUTION BOX TO GRADE 4" DIA SEWER PIPE (1% MIN SLOPE TO CHAMBERS) PROFILE HOLE 25' MIN. D,c� � GULCH i ARC ADS CHAMBER BED. 4 ROWS OF 14 = 56 CHAM ERS =691 SF S[R!ICE 33 Four WheelCarbondalqeCO Dri81ve623 Road , !} I C 970.309.5259 Niccoli Residence 2074 CR 109 Garfield County, Colorado Project Number: C1076 Date: 05/07/14 Designed By: CBO Reviewed By: RHP Drawn By: ANG W2.0 Sheet 2 of 6 NOTES: BED MAY BE ANGLED TO FIT TOPOGRAPHY AND TO MINIMIZE REMOVAL OF EXISTING VEGETATION. LIMITATIONS - THESE PLANS MUST BE USED IN CONJUNCTION WITH LETTER AND SOILS DATA FORM PROVIDED. THE DESIGN IS BASED UPON INFORMATION SUBMITTED. IF SOIL CONDITIONS ENCOUNTERED ARE DIFFERENT FROM CONDITIONS DESCRIBED IN REPORT, ALL SERVICE SEPTIC L.L.C. SHOULD BE NOTIFIED. ALL OWS CONSTRUCTION MUST BE ACCORDING TO COUNTY REGULATIONS. THE INSTALLER SHOULD HAVE DEMONSTRATED KNOWLEDGE OF THE REQUIREMENTS AND REGULATIONS OF THE COUNTY IN WHICH THEY ARE WORKING. THE COUNTY AND ALL SERVICE SEPTIC L.L.C.MUST VIEW INSTALLATION. ARC ADS CHAMBER BED INFILTRATOR END PLATE PLAN VIEW - TYP. 70' 56 ARC ADS CHAMBERS 12' r,: 0 ' OBSERVATION PIPE CHAMBER BED DETAIL 3 NOT TO SCALE 4" EFFLUENT PIPE FROM SEPTIC TANK '—D -BOX TO GRADE PIPES PLACED IN TOP PORT OF CHAMBER END PLATES HIl t HID (11:4) 33 Four Wheel Drive Road Carbondale, CO 81623 970.309.5259 Niccoli Residence 2074 CR 109 Garfield County, Colorado Project Number. C1076 Date: 05/07/14 Designed By: CBO Reviewed By: RHP Drawn By: ANG W3.0 Sheet 3 of 6 4" SDR 35 PVC OBSERVATION / VENT PIPE WITH CAP 3' MAX EXTENT OF EXCAVATION CROSS SECTION OF TYPICAL CHAMBER BED BACKFILL (MUST BE MINUS 3 -INCH MATERIAL) SLOPE FOR DRAINAGE ARC ADS (R) CHAMBER, 3'X5' BED 2' MIN 5" CONCRETE SAND UNDER CHAMBERS j SCARIFY SURFACE BED MUST BE LEVEL. CHAMBER BED DETAIL t NOT TO SCALE RIL �E (100)33 Four Wheel Drive Road Carbondale, CO 81623 c 970.309.5259 Niccoli Residence 2074 CR 109 Garfield County, Colorado Project Number C1076 Date: 05/07/14 Designed By: CBO Reviewed By: RHP Drawn By: ANG W4.0 Sheet 4 of 6 DESIGN 5 -BEDROOM RESIDENCE (75 GAL/PERSON/DAY x 2 PERSONS/BEDROOM x 5 BEDROOMS) AVERAGE DAILY FLOW = 750 GALLONS DESIGN FLOW = Q = 1.5 x 750 = 1125 GALLONS TANK: 1125 x 30 HOUR RETENTION TIME = 1406 GALLONS USE EXISTING1500-GALLON, TWO-COMPARTMENT TANK ABSORPTION AREA: LONG TERM ACCEPTANCE RATE (LTAR) = 1.0 GAL/ SQ FT CALCULATED ABSORPTION AREA = Q/LTAR = 1125 SF 40% REDUCTION, CHAMBER BED TOTAL REQUIRED AREA = 675 SQUARE FEET 4 ROWS OF 14 ARC ADS CHAMBERS = 56 CHAMBERS BOX AND COVER BROUGHT TO GRADE CONCRETE LID FINSHED GRADE DISTRIBUTION BOX OD—BOX DETAIL NOT TO INLET BAFFLE RLL SENE 33 Four Wheel Drive Road Carbondale, CO 81623 970.309.5259 Niccoli Residence 2074 CR 109 Garfield County, Colorado Project Number: C1076 Date: 05/07/14 Designed By: CBO Reviewed By: RHP Drawn By: ANG W5.0 Sheet 5 of 6 vas i, qlorp L!1t 1 111 . 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