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Home My WebLink AboutOWTS Design 2789 Riverside Parkway Grand Junction, Colorado 81501 Phone: 970-255-8005 Info@huddlestonberry.com October 4, 2022 Project#02196-0007 Wiseland Construction 3677 G 4/10 Road Palisade, Colorado 81526 Attention: Mr. Parker Moreland Subject: OWTS Design 515 Stover Valley Road Glenwood Springs, Colorado Reference: Geotechnical Investigation, 515 Stover Valley Road, Glenwood Springs, Colorado by Huddleston-Berry Engineering & Testing, LLC for Parker Moreland, September 19, 2022. Dear Mr. Moreland, At your request, Huddleston-Berry Engineering & Testing, LLC completed design of an Onsite Wastewater Treatment System (OWTS) for a single-family residence at 515 Stover Valley Road in Glenwood Springs, 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, the western portion of the site was occupied by an existing residence and shop structure. The remainder of the site was open and sloping down towards the west. Site topography is shown on Figure 2. Vegetation consisted primarily of weeds, grasses, and brush. The site was bordered to the north and west by rural residential properties and to the south and east by vacant residential parcels. Subsurface Investigation As discussed in the referenced report, the subsurface conditions at the site were fairly consistent. The test pits encountered 2.0 feet of topsoil above tan, dry to moist, medium dense to dense silty sand with gravel and cobble soils to the bottoms of the excavations. Groundwater was not encountered in the subsurface at the time of the investigation. Although groundwater was not encountered during the subsurface investigation, HBET believes that the seasonal high groundwater elevation is deeper than 8.0 feet below the existing grade at this site. The locations of the test pits are shown on Figure 2. Copies of the test pit logs are included in Appendix A. 515 Stover Valley Rd. #02196-0007 10/04/22 Z:\2008 ALL PROJECTS\02196 - Wiseland Construction\02196-0007 515 Stover Valley Road\200 - Geo\02196-0007 LR100422.doc 2 Onsite Wastewater Treatment System In order to evaluate the site soils for onsite wastewater treatment, percolation testing was conducted at the site. The percolation rate in the native soils ranged from 4 to 5 minutes-per- inch. The percolation testing data are included in Appendix C. In accordance with Garfield County regulations, a percolation rate of between 5 to 60 minutes- per-inch is required for soils to be deemed suitable for onsite wastewater treatment. Although the percolation rates were fairly fast, the native soils contain an appreciable quantity of fines and will provide excellent filtration of effluent. Therefore, based upon the results of the percolation testing, HBET believes that the native soils are suitable for onsite wastewater treatment. In addition to the percolation rate of the subsurface materials, the seasonal high groundwater elevation is an important factor in determining the suitability of the site for Onsite Wastewater Treatment Systems. For OWTS suitability, the seasonal high groundwater elevation should be at least four feet below the bottom of the proposed absorption bed. As discussed previously, groundwater was not encountered at the time of the investigation. In general, based upon the results of the subsurface investigation, HBET believes that the seasonal high groundwater level is deeper than 8.0 feet below the existing grade at this site. 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 June 2018. The proposed construction at the site is anticipated to include a garage containing a bathroom. The proposed bathroom is anticipated to include a water closet (toilet) and sink. Based upon the soil percolation rate and visual tactile classification of the soils, a Long-Term Acceptance Rate (LTAR) of 0.6 will be utilized for the absorption field design. Infiltrator Systems Quick4 Standard Chambers are proposed. 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 = (24.8 GPD/water closet)+(5.8 GPD/sink) = 31 GPD Soil Treatment Area = (31 GPD / 0.6) = 51 Square Feet Adjusted Soil Treatment Area = (51 SF)(1.2)(0.7) = 43 Square Feet # of Quick4 Chambers = (43 / 12) = 4 Chambers 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: 515 Stover Valley Rd. #02196-0007 10/04/22 Z:\2008 ALL PROJECTS\02196 - Wiseland Construction\02196-0007 515 Stover Valley Road\200 - Geo\02196-0007 LR100422.doc 3 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 Infiltrator chambers. 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. 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 10/04/22 FIGURES Garfield County, CO Developed by Date created: 8/18/2022 Last Data Uploaded: 8/18/2022 5:53:17 AM 6,406 ft 7562 7564 7566 7560 7558 7556 7554 2789 Riverside Parkway Grand Junction, CO 81501 Project No.: 02196-0007 Date: 10/04/22 By: MAB 515 STOVER VALLEY ROAD PARCEL#218735100010 FIGURE 2 - SITE PLANTEST PIT C.I. = 2 FT SCALE: 1" = 200' **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.** SITE PLAN ENLARGED VIEW ~50' ~90' (10' MIN) ~278' ~125'~150' ~30' ~80' ~375' ~475'~435' ~40' ~33' ~265' (100' MIN) TP-1 TP-2 7568 16' ~41'~34' 5' MIN ~78' ~32' 3' TP-1 TP-2 C.I. = 2 FT SCALE: 1" = 30' REPAIR AREA STA EXISTING GARAGE MINIMUM 1,000 GALLON TANK WATER LINE EXISTING HOME EXISTING GARAGE EXISTING STA NEW STA EXISTING SEPTIC TANK WATER LINES WELL DRIVEWAY 10/04/22 2789 Riverside Parkway Grand Junction, CO 81501 Project No.: 02196-0007 Date: 10/04/22 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' 515 STOVER VALLEY ROAD PARCEL#218735100010 FIGURE 3 - SEPTIC SYSTEM DETAILS 5' MIN 20' MIN SEPTIC TANK WITH MINIMUM 1,000 GALLON CAPACITY INFILTRATOR SYSTEMS QUICK4 STANDARD CHAMBERS EXISTING GARAGE 4-INCH DIAMETER SEWER AND EFFLUENT PIPE MEETING ASTM D1785, SCHEDULE 40 OR SDR 35 WATER LINE 16' 3' INSPECTION PORT GENERALIZED SYSTEM PROFILE GENERALIZED BED PROFILE COVER SOIL; NATIVE SOILS OR OTHER SUITABLE TOPSOIL. GRADE TO CARRY SURFACE WATER AWAY FROM BED. NONWOVEN, NEEDLE PUNCHED, GEOTEXTILE FABRIC IMMEDIATELY ABOVE CHAMBERS INFILTRATOR SYSTEMS QUICK4 STANDARD CHAMBERS INSPECTION PORT 10/04/22 APPENDIX A Typed Test Pit Logs Silty Sand with Cobbles and Organics (TOPSOIL) Silty SAND with Gravels and Cobbles (SM), tan, dry to moist, medium stiff to stiff GB-1: Lab Classified Bottom of test pit at 8.0 feet. GB 1 455413299 NOTES GROUND ELEVATION LOGGED BY TC 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 8/19/22 COMPLETED 8/19/22 DEPTH(ft)0.0 2.5 5.0 7.5 GRAPHICLOGATTERBERG LIMITS MATERIAL DESCRIPTION SAMPLE TYPENUMBERFINES CONTENT(%)RECOVERY %(RQD)BLOWCOUNTS(N VALUE)POCKET PEN.(tsf)DRY UNIT WT.(pcf)MOISTURECONTENT (%)LIQUIDLIMITPLASTICLIMITPLASTICITYINDEXPLASTICITYINDEXPAGE 1 OF 1 TEST PIT NUMBER TP-1 CLIENT Wiseland Construction PROJECT NUMBER 02196-0007 PROJECT NAME 515 Stover Valley Road PROJECT LOCATION Glenwood Springs, CO GEOTECH BH COLUMNS 02196-0007 515 STOVER VALLEY ROAD.GPJ GINT US LAB.GDT 9/15/22Huddleston-Berry Engineering & Testing, LLC 2789 Riverside Parkway Grand Junction, CO 81501 970-255-8005 Silty Sand with Cobbles and Organics (TOPSOIL) Silty SAND with Gravels and Cobbles (sm), tan, dry to moist, medium dense to dense Bottom of test pit at 8.0 feet. NOTES GROUND ELEVATION LOGGED BY TC 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 8/19/22 COMPLETED 8/19/22 DEPTH(ft)0.0 2.5 5.0 7.5 GRAPHICLOGATTERBERG LIMITS MATERIAL DESCRIPTION SAMPLE TYPENUMBERFINES CONTENT(%)RECOVERY %(RQD)BLOWCOUNTS(N VALUE)POCKET PEN.(tsf)DRY UNIT WT.(pcf)MOISTURECONTENT (%)LIQUIDLIMITPLASTICLIMITPLASTICITYINDEXPLASTICITYINDEXPAGE 1 OF 1 TEST PIT NUMBER TP-2 CLIENT Wiseland Construction PROJECT NUMBER 02196-0007 PROJECT NAME 515 Stover Valley Road PROJECT LOCATION Glenwood Springs, CO GEOTECH BH COLUMNS 02196-0007 515 STOVER VALLEY ROAD.GPJ GINT US LAB.GDT 9/15/22Huddleston-Berry Engineering & Testing, LLC 2789 Riverside Parkway Grand Junction, CO 81501 970-255-8005 APPENDIX B Percolation Testing Results Project Name: SOIL PROFILE (ft) (ft) (ft) (in) (in) (in) (in) (in) (in) (min.) (in.) (in.) (min.) (in.) (in.) (min.) (in.) (in.) Rate (min/in): Rate (min/in): Rate (min/in): Average Percolation Rate (min/in): 515 Stover Valley Rd. City:Glenwood Springs Date: 8/19/2022 Testing Conducted By: T. Collins PERCOLATION TESTING STP322 Project No. 02196-0007 Test Pit No. TP-2 State Colorado Supervising Engineer: M. Berry TEST PIT DIMENSIONS Length (ft) Width (ft) Depth (ft) Water Level Depth (ft) Depth (ft) Not Encountered Remarks 0-2 Silty Sand with Cobbles and Organics (TOPSOIL) 2-8 Silty SAND with Gravels and Cobbles (sm), tan, dry to moist, medium dense to dense 8.0 X Depth (ft)Description Top of Hole Depth: 2 Top of Hole Depth: 4 Top of Hole Depth: Test Number: 1 Test Number: 1 Test Number: Depth of Hole: 13 Depth of Hole: 12 Depth of Hole: Diameter of Hole: 4 Diameter of Hole: 4 Diameter of Hole: Time Water Depth Change 02 02.25 Time Water Depth Change Time Water Depth Change 10 8.25 6.25 10 7.75 5.5 20 12.25 4 20 12 4.25 40 0.75 40 0.75 30 Dry 30 Dry 50 2.75 2 50 3.25 2.5 60 4.5 1.75 60 4.75 1.5 80 11.25 5.5 80 Dry 70 5.75 1.25 70 11 6.25 90 Dry 90 0.5 100 0.625 100 2.75 2.25 120 4.625 1.75 120 8.25 2.25 110 2.875 2.25 110 6 3.25 54 5