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Home My WebLink AboutOWTS Design 2789 Riverside Parkway Grand Junction, Colorado 81501 Phone: 970-255-8005 Info@huddlestonberry.com September 21, 2021 Project#02266-0006 Factory Direct Housing 2302 Highway 6 & 50 Grand Junction, Colorado 81505 Attention: Mr. Jon Ford Subject: OWTS Design Parcel 217903400012 Silt, Colorado Dear Mr. Ford, At your request, Huddleston-Berry Engineering & Testing, LLC completed design of an Onsite Wastewater Treatment System (OWTS) for a single-family residence at Parcel 217903400012 in Silt, Colorado. The site location is shown on Figure 1 – Site Location Map. A site plan is included as Figure 2. Site Description At the time of the investigation, excavation had been conducted into the native hillside resulting in an approximate 20-foot cut. The perimeter of the site was fenced and sloping down towards the south outside the excavated area. Site topography is shown on Figure 2. Vegetation consisted of weeds, grasses, and sparse small to large bushes and trees. The site was bordered to the west, east, and south by residential properties, and to the north by a cliff face. Subsurface Investigation In order to evaluate the subsurface conditions at the site, two test pits were excavated in the vicinity of the proposed OTWS. The locations of the test pits are shown on Figure 2. Copies of the test pit logs are included in Appendix A. As indicated on the logs, the subsurface conditions at the site were consistent. The test pits generally encountered brownish tan, moist, loam soils from the ground surface to the bottoms of the excavations. The soils were subangular blocky with a strong structure. Groundwater was not encountered in the subsurface at the time of the investigation. In general, HBET believes that the seasonal high groundwater elevation is deeper than 8.0 feet at this site. Onsite Wastewater Treatment System Seepage Bed Design The design of the absorption system generally follows the requirements of the Garfield County Department of Public Works as outlined in the Garfield County On-Site Wastewater Treatment System Regulations, effective July 2019. The proposed construction at the site is anticipated to include a three-bedroom home. Parcel 2179034000012 #02266-0006 09/21/21 Z:\2008 ALL PROJECTS\02266 - Factory Direct Housing\02266-0006 13th and Linda Street\200 - Geo\02266-0006 LR092121.doc 2 Based upon visual-tactile evaluation of the site soils, a Long-Term Acceptance Rate (LTAR) of 0.6 will be utilized for the absorption field design. The daily flow of the sewage disposal system is calculated below and a plan and profile of the absorption system are shown on Figure 3. Average Daily Flow = (6 persons)(75 GPD/person) = 450 GPD Soil Treatment Area = (450 GPD / 0.6) = 750 Square Feet Adjusted Soil Treatment Area = (750 SF)(1.2)(1.0) = 900 Square Feet Size of STA = 12 ft x 75 ft System Installation The installation of the septic tank, plumbing lines, Infiltrators, etc. should be completed in accordance with the Garfield County On-Site Wastewater Treatment System Regulations and Infiltrator Systems, Inc. specifications. In addition, the following construction procedures are recommended:  The septic tank and distribution box should be placed level over native soils that have been scarified to a depth of 8 to 12 inches, moisture conditioned, and recompacted to a minimum of 95% of the standard Proctor maximum dry density, within ±2% of optimum moisture content. However, up to 3-inches of washed rock or pipe bedding passing the 1-inch sieve may be used as a leveling course under the septic tank and/or distribution box.  The bottoms of trenches and backfill around the septic tank and distribution box which will support sewer or effluent lines should be compacted to at least 90 percent of the standard Proctor maximum dry density, within ±2% of optimum moisture content. Pipe bedding should have a maximum particle size of 1-inch.  Vehicular or heavy equipment traffic and placement of structures should not encroach within 10 feet of the septic tank or distribution box. Inspection Schedule Huddleston-Berry Engineering & Testing LLC should be retained to monitor the construction of the OWTS. The following schedule of observation and/or testing should be followed:  Observe the absorption bed excavation prior to placement of pipe and gravel.  Observe placement of the septic tank, distribution box, and all connecting sewer and effluent lines prior to backfill. Verify proper fall between inverts.  Observe and verify installation of the absorption bed prior to placement of cover and backfill. In conformance with Garfield County regulations, HBET will be required to provide the Garfield County Health Department with documentation certifying that the OWTS was placed in conformance to the plan and profile and Garfield County regulations. General Notes The OWTS design was based upon the results of the subsurface investigation and on our local experience. The design is valid only for the proposed construction. Parcel 2179034000012 #02266-0006 09/21/21 Z:\2008 ALL PROJECTS\02266 - Factory Direct Housing\02266-0006 13th and Linda Street\200 - Geo\02266-0006 LR092121.doc 3 We are pleased to be of service to your project. Please contact us if you have any questions or comments regarding the contents of this report. Respectfully Submitted: Huddleston-Berry Engineering and Testing, LLC Michael A. Berry, P.E. Vice President of Engineering 09/21/21 FIGURES Developed by Date created: 8/19/2021 Last Data Uploa ded: 8/19/2021 2:09:51 AM 1,601 ft 2789 Riverside Parkway Grand Junction, CO 81501 Project No.: 02266-0006 Date: 09/21/21 By: MAB PARCEL#217903400012 FIGURE 2 - SITE PLANTEST PIT C.I. = 2 FT SCALE: 1" = 40' **NOTE:TANK AND BED LOCATIONS APPROXIMATE AND MAY SHIFT SOME DURING CONSTRUCTION BASED UPON SITE TOPOGRAPHY, OWNER PREFERENCE, AND/OR OTHER FACTORS AS LONG AS APPLICABLE SETBACKS ARE MET. ACTUAL LOCATION OF TANK AND BED WILL BE INDICATED ON AS-BUILT DRAWINGS.**54805490 5500 5510 5520 5530 5500 547025' TO CREST OF SLOPE MIN. ~24'64' 29'5' ~32' ~30' ~24' ~40' ~120' TP-1 TP-2 REPAIR AREA STA WATER LINE NEW HOME MINIMUM 1,000 GALLON TANK 75' 12' 09/21/21 2789 Riverside Parkway Grand Junction, CO 81501 Project No.: 02266-0006 Date: 09/21/21 By: MAB MINIMUM SETBACKS (UNITS = FT) **OTHER SETBACKS NOT LISTED HERE SHOULD BE IN ACCORDANCE WITH GARFIELD COUNTY OWTS REGULATIONS **USE SWEEP 90'S OR TWO 45'S AT 90 DEGREE BENDS** DETAIL AREA SCALE: 1" = 20' PARCEL#217903400012 FIGURE 3 - SEPTIC SYSTEM DETAILS 75' 20' MIN 4-INCH DIAMETER SEWER AND EFFLUENT PIPE MEETING ASTM D1785, SCHEDULE 40 OR SDR 35 DISTRIBUTION BOX THAT ENSURES EVEN DISTRIBUTION OF EFFLUENT SEPTIC TANK WITH MINIMUM 1,000 GALLON CAPACITY WATER LINE 4-INCH DIAMETER PERFORATED PIPE NEW HOME INSPECTION PORTS INSPECTION PORTS GENERALIZED SYSTEM PROFILE GENERALIZED BED PROFILE 5' MIN SEEPAGE BED CONSTRUCTED OF 1.5 INCH MINUS WASHED ROCK COVER SOIL; NATIVE SOILS OR OTHER SUITABLE TOPSOIL 4-INCH DIAMETER PERFORATED PIPE 12' 4' 2' 09/21/21 APPENDIX A Typed Test Pit Logs 8.0 Loam, brownish-tan, moist, subangular blocky, moderate structure, firm **Topsoil Stripped Bottom of test pit at 8.0 feet. NOTES GROUND ELEVATION LOGGED BY SD EXCAVATION METHOD Trackh/Backhoe AT TIME OF EXCAVATION dry AT END OF EXCAVATION dry AFTER EXCAVATION --- TEST PIT SIZE EXCAVATION CONTRACTOR Client GROUND WATER LEVELS: CHECKED BY MAB DATE STARTED 7/20/21 COMPLETED 7/20/21 DEPTH(ft)0.0 2.5 5.0 7.5 SAMPLE TYPENUMBERPAGE 1 OF 1 TEST PIT NUMBER TP-1 CLIENT Factory Direct Housing PROJECT NUMBER 02266-0006 PROJECT NAME Parcel 217903400012 PROJECT LOCATION Silt, CO GENERAL BH / TP / WELL 02266-0006 13TH AND LINDA STREET USDA.GPJ GINT US LAB.GDT 9/16/21Huddleston-Berry Engineering & Testing, LLC 2789 Riverside Parkway Grand Junction, CO 81501 970-255-8005 GRAPHICLOGMATERIAL DESCRIPTION 8.0 Loam, brownish-tan, moist, subangular blocky, moderate structure, firm **Topsoil Stripped Bottom of test pit at 8.0 feet. NOTES GROUND ELEVATION LOGGED BY SD EXCAVATION METHOD Trackh/Backhoe AT TIME OF EXCAVATION dry AT END OF EXCAVATION dry AFTER EXCAVATION --- TEST PIT SIZE EXCAVATION CONTRACTOR Client GROUND WATER LEVELS: CHECKED BY MAB DATE STARTED 7/20/21 COMPLETED 7/20/21 DEPTH(ft)0.0 2.5 5.0 7.5 SAMPLE TYPENUMBERPAGE 1 OF 1 TEST PIT NUMBER TP-2 CLIENT Factory Direct Housing PROJECT NUMBER 02266-0006 PROJECT NAME Parcel 217903400012 PROJECT LOCATION Silt, CO GENERAL BH / TP / WELL 02266-0006 13TH AND LINDA STREET USDA.GPJ GINT US LAB.GDT 9/16/21Huddleston-Berry Engineering & Testing, LLC 2789 Riverside Parkway Grand Junction, CO 81501 970-255-8005 GRAPHICLOGMATERIAL DESCRIPTION