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HomeMy WebLinkAboutAs-Built OWTS Report 06.25.16Jason Anthony Clearwater Construction Management Inc. POBox6236 Snowmass Village, CO, 81615 janthony@ccmaspen.com July 25, 20161 RE: AS-BUILT; Onsite Wastewater Treatment System (OWTS), Anthony Residence, Lot 16 Callicotte Ranch Subdivision, C.R. 103, Garfield County, Colorado SE Job No. 16090.01 Parcel Number: Parcel Number: 2393-242-06-016 Dear Jason: Pursuant to County requirements, this letter provides documentation that the new Onsite Wastewater Treatment Systems (OWTS) recently installed at the above referenced site is in compliance with the pennitted design. Sopris Engineering inspected the excavations, soils, materials and the installation of the system components at various times during construction, prior to final backfill and after all installations was completed. The system constructed on site was designed and built to serve the needs of residence currently under construction. The installed system was designed with a maximum treatment capacity equivalent for typical 4-bedroom home. Sopris Engineering performed site visits to inspect and document the as-built conditions of the constructed system. Inspections were coordinated with the earthmoving contractor, Hughes Excavating Company. The as- built conditions and instaJlation of the new OWTS components is in compliance with Garfield County Regulations; the recommendations and specifications delineated on the civil OWTS design plan. Cl-OWTS Plan. stamp dated 6-3-2016. by Sopris Engineering. The design criteria and system sizing information is summarized below. An As-built OWTS record drawing is attached delineating the As-built descriptions and location of the components. Design Criteria and As-built Svstem Comnonent Installation The system was designed based on the design criteria approved for use of Soil Treatment Unit (STU) systems. The OWTS includes the installation of a 1250 gallon 2-compartment concrete septic tank with concrete risers and lids installed at the surface. The tank was installed with an inlet sanitary tee and an outlet effluent filter sanitary tee. A gravity schedule-40 sewer pipe with a cleanout is installed from the residence to the tank. The soil treatment unit (STU), consists of 3 leaching chamber trenches that provides 612 S.F. of total absorption area. The septic tank effluent is equally distributed by gravity, via a distribution box, to the STU. The effluent is distributed through a concrete distribution box installed with risers and lid at the surface and individual distribution pipes connected to the head end cap of each chamber trench. Observation ports with caps were installed on each end chamber unit. The design is in compliance with the current County regulations with design calculations based on the soil type, texture and structure with an appropriate long term acceptance rate (I.TAR). I 502 Main Street • Suite A3 • Carbondale, CO 81623 • (970) 704-0311 • Fax (970) 704-0313 I SOPRIS ENGINEERING • llC civil consultants Sub Surface Conditions and observation AS-BUILT, OWTS Anthony Residence SE Job No. 16090.01 July 25, 2016 Subsurface soil investigations and USDA soil texture method tests were performed by Sopris Engineering on April 22, 2016. The soils in the area of the proposed absorption field were sampled and characterized by application of the USDA soil texture method analysis. The soils were tested to determine the hydraulic loading rate and the appropriate absorptive surface depth in the native soils. A shallow and deep excavated pit was observed in the North central portion of the site. The soils below 6 to 12 inches oftopsoiJ consist of medium dense silt loam with granu1ar structure to the 8 foot depth explored. The native soils sampled from 1-3 feet below the surface are characterized as a soil type 2 consisting of silt 1oam texture with granular structure. This soil has an effective loading rate for conventional soil treatment of 0.60 gal/S.F./day for a level l conventional treatment system. The equivalent percolation rate is approximately 16-25 minutes per inch. No free water was encountered in excavations on site. No excessive boulders or cobbles were encountered during excavation. Observations of the soils, in the excavation during construction, appeared to be consistent with the previous subsurface soil investigation. Design Flow The design flow is calculated as follows: The new OWfS shall be based on a minimum 4-bedroom capacity for single family residence. From the Garfield County OWTS Regulation 43 ; Minimum population based on 2 persons per bedroom for first 3 bedrooms & 1 person per bedroom for each additional bedroom 3 bedrooms @2 person /bedroom= 6 persons. 1 bedrooms @ 1 person /bedroom = 1 persons. Gallons per day per person =75 gaJ/person/day, No peaking factor Max. Design flow (Qd) gallons/day=(# of people) x (avg. flow)gal/person/day. Design flow Qd = 7*75=525 gpd Treatment-Soil Treatment Unit/ Absomtion System Design The treatment/absorption field was designed based on utilizing the effective Long Tenn Acceptance Rate (LT AR) for the native soils and the application of appropriate loading factors for a soil treatment unit system utilizing gravity distribution to gravelless chamber trenches. The new treatment system and absorption field consist of gravity distribution of septic tank effiuent via a distribution box to individual chamber trenches with treatment across the native soil absorptive surface. Long Tenn Acceptance Rate (LTAR) Considering the application of the new state regulation43: Receiving Wastewater Treatment Level 1; loading rate for silt loam is (0.60 gal./S.F./day) for soil type 2.; Loading factors; (Table 10-2, Gravity application trenches= 1.0) and (Table 10-3, gravelless chambers = 0.7) A(sf) = Qd x L.F.: A= Area; LTAR LTAR = 0.60 Gal/S.FJday for silt loam Qd = flow (gaVday) = 525 gpd L.F.1=1.0 Gravity Distribution L.F.2=0.7 Chambers A(st) = 525gpdx1.0x 0.7=612 S.F. 0.60 Gal/S.F Jday Number of quick-4 chambers: 6128.F = 51 chambers Use 51cbambers 12 S.F./Chamber AS-BUILT, OWTS Anthony Residence SE Job No. 16090.01 July 25, 2016 51 Quick-4 chambers in three trenches 70' long by 3' wide with 17 chambers units per trench plus two end caps was installed as delineated on the attached As-Built Record drawing. OWS Operation and Maintenance Ownership of the system and responsibility for maintenance and repair will remain with the property Owner. The Owner is encouraged to retain the services of qualified personnel to inspect the owrs and to perform all maintenance and repairs necessary to ensure that the system components are maintained in good operating condition and suitable vegetative cover is established on the fields. The components of the OWTS system should inspected within 30 days of being placed into operation and should been inspected and maintained bi- annually. The tank, absorption field and other system components should be visually inspected bi-annually for debris, damage, leaks, or other potential problems . In general, for a properly utili:zcd system, septic tanks should be pumped every 3 -5years. The effluent filter should be cleaned every six months and at the time of pumping. Absorption fields should be maintained with suitable vegetative cover and kept free of root invasive plants. Positive surface drainage away from the absorption field should be maintained. 1f you have any question or need any additional information, please call.