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HomeMy WebLinkAboutDesign PlansIcCC/ ENGINEERING 1129 -za- Road Cronk Construction Inc. Grand Junction, CO 81505 Grand Junction (970) 245-0577 • Glenwood Springs/Aspen (970) 640-5029 • Montrose/Delta (970) 640-5029 Email: ccigj@msn.com ONSITE WASTEWATER TREATMENT SYSTEM DESIGN Date: January 28, 2015 Prepared by: Thomas A. Cronk, P.E. Cronk Construction Inc. 1129 -24- Road Grand Junction, CO 81505 245-0577 Type of Design: commercial repair Client: Vision Oil Tools 0193 Bud's Way Parachute, CO 81635 970-285-9912 Property address: 0193 Bud's Way, Parachute, CO 81635 Tax schedule No.: 2409-273-10-004 Legal Descript.: 1 1.0 Site History The site consists of approximately 2.50 acres of uncultivated native soil. Drainage varies across the site and is approximately 3% to the south in the area of concern. A percolation test/soils evaluation was conducted on the property of reference on 01/23/15 by Tom A. Cronk, registered professional engineer (R.P.E.). The perc excavation trench (excavation A) was located 60' south of the north property line and 14' east of the west property line. Additional perc holes were located 30' south of the north property line and 25' east of the west property line (excavation B) and 40' south of the north property line and 75' east of the west property line (excavation C). An existing onsite wastewater treatment system (OWTS) currently serves a commercial building located on the property. The existing OWTS is failing and the owners wish to install a repair OWTS. Based on results from the 01/23/15 investigation, a repair engineered OWTS design has been prepared for the property. A discussion of developed subsurface design parameters and the engineered OWTS design follows. The 01/23/15 perc test/soils evaluation is attached for reference as Appendix A. 2.0 Development of Design Parameters A perc excavation trench (excavation A) was extended to a depth of 120" below ground surface (BGS). There was no evidence of ground water or high seasonal water table in the open excavation to a depth of 120" BGS. The soils evaluation indicates three distinct soil horizons underlie the site. A Iithological description follows: depth (in.1 description 0" — 12" gravel manfill 12" — 72" sandy clay/minor sand lenses, brown 72" — 120" sand/clayey sand, light brown; friable As based on the results from the 01/23/15 site investigation (Appendix A), a design perc rate of 60 min/in. and corresponding long term acceptance rate (LTAR) of 0.35 is chosen for overall system sizing for an infiltrator trench absorption field designed to discharge to subsoils below the 36" depth. 3.0 System Design A STANDARD INFILTRATOR absorption trench system is proposed for discharge of septic effluent at the site. As shown on the attached graphics, the repair STA will be placed in the same area as the existing absorption field. To facilitate installation of the repair STA, the existing absorption area will be removed. All affected soil will be removed and replaced with replacement soil meeting ASTM 33 standard for concrete sand. Construction of the system will consist of excavating level trenches in the area comprising the repair soil treatment area (STA). Each trench excavation shall be continued to a depth of 84" BGS (see absorption field cross-section). After removal of surface soils, the open excavations will be disked or scarified and backfilled to a depth of 36" BGS (i.e., 48" of backfill) with bedding sand. The bed sand will meet the ASTM 33 criteria for concrete sand. Following placement of the bedding sand, INFILTRATORS (QUICK4 STANDARD or equivalent) will be used to construct a septic effluent distribution system. The INFILTRATOR effluent distribution system will be installed in accordance with the "Infiltrator Technical Manual", available from Infiltrator Systems Inc., 123 Elm Street, Suite 12, Old Saybrook, Connecticut 06475. Adjacent INFILTRATORS shall be fastened with a minimum of four (4) 3/4" x #8 self-tapping sheet metal or bright brass deck screws to prevent movement and separation during backfilling. After the INFILTRATORS are installed, synthetic filter fabric (140-200 mesh) will be placed over the INFILTRATORS and the system will be covered with a soil cap. The soil cap will consist of approximately 24" of sandy loam soil mounded 5% to promote surface run off away from the absorption field. The installer should confirm the feasibility of gravity discharge of sewage effluent from the structure to the absorption field by field verification of assumed design parameters. Assumed design parameters with respect to gravity discharge include: • distance from exit of sewage pipe at the septic tank to the STA - 25' or less, • elevation of ground surface at entry to STA must be no more than 24" above the invert elevation of sewage pipe at exit from the septic tank. If field measurements do not confirm these design assumptions, gravity discharge of septic effluent from the proposed structure cannot be assured and a lift station may be required. Please contact the design engineer to address any design modifications necessary if these design assumptions are not upheld. The installer must also confirm the setbacks from property lines, building envelopes, and existing easements shown in the attached graphics are maintained. Four inch clean outs shall be provided at maximum 100' intervals in all effluent lines exceeding 100' in length. Vehicle traffic and parking is to be prevented over the absorption and repair area. Provide minimum schedule 40 PVC under all traffic areas. Additionally, effluent piping in traffic areas with less than 24" of cover shall be encased in 6" CMP or flow fill and covered with minimum 2" high density blue board insulation. The sewer line shall be encased with minimum 6" PVC with water-tight end caps a minimum of 10' to either side of all domestic water line crossings. Finally, any unknown utility lines, easements, or other adverse conditions disclosed during construction must maintain the required setbacks listed on page 6 of this document. 3 The existing septic tank will be retained for use with the repair STA. A non -corrodible Orenco filter (model # FTW0444-36) shall be installed at the final outlet Tee of the existing septic tank or in the effluent line between the septic tank and the STA to limit the size of solids and sludge passing into the absorption fields. The filter must be accessible for cleaning and replacement from the ground surface. A distribution box is required to provide equal distribution of septic effluent from the septic tank to the absorption field laterals. The distribution box must be placed on stable native soil or compacted structural fill to prevent settling and assure equal distribution of septic effluent. The repair STA will be sized to accept sewage from a maximum of 15 office employees at the facility. Loading estimates follow. Source Loading Daily Sewage Loading (gal./dav) 15 office employees 15 gal./day-employee 225 gal./day Total Sewage Loading 225 gal./day As discussed above, INFILTRATOR absorption trenches are proposed to discharge septic effluent to the underlying sub -soils. As shown in the attached graphics, the absorption trenches will consist of three (3) trenches 3' wide x 3' deep x 52' long with thirteen (13) STANDARD INFILTRATOR (or equivalent) units each for a total of thirty nine (39) units. The absorption field will encompass an area of 468 square feet with an effective area of 668.57 sq. ft. Calculations and design parameters used to size the absorption field follow. 4 DESIGN CALCULATIONS DESIGN FLOW OF 225 GAL./DAY DESIGN PERCOLATION RATE = 60 MIN.IINCH DESIGN LONG TERM ACCEPTANCE RATE (LTAR) = 0.35 GAL./DAY-SQ. FT. A = LTAR' WHERE, A = ABSORPTION FIELD AREA Q= DESIGN FLOW LTAR = LONG TERM ACCEPTANCE RATE (GAL./DAY-SQ. FT.) A = 225 0.35 642.86 ABSORPTION FIELD AREA ADJUSTMENT FACTOR FOR TRENCH DESIGN - 1.0 ABSORPTION FIELD AREA ADJUSTMENT FACTOR FOR USE OF CHAMBERS = 0.7 ADJUSTED ABSORPTION FIELD AREA = 642.86 X 1.0 X 0.7 = 450 SQ. FT. USE 39 STANDARD INFILTRATORS CONFIGURED AS A TRENCH DESIGN OF 3 ROWS OF 13 UNITS EACH ROW (3 ROWS AT 3' X 52' IN SIZE) ABSORPTION FIELD ADDITION SIZED AT 3 X 3 FT. X 52 FT. = 468 SQ. FT. 4.0 Site Specific Installation/Operation Requirements The owner and system contractor shall be aware and comply with the following installation and system operation requirements. 4.1 Installation - Setbacks, Notifications, and Inspections • All installation activities shall be conducted in accordance with current Garfield County Resolution No. 14-22. If at any time during construction, subsurface site conditions are encountered which differ from the design parameters developed in Section 2.0, construction activities will stop and the des$n engineer will be contacted to address any necessary design modifications. • Installation procedures including grade, location, setbacks, septic tank size, and absorption field size shall conform with the attached graphic details. Construction activities and system components will not encroach upon existing easements or utility corridors. A minimum of 6 ft. of undisturbed soil shall be maintained between individual absorption elements and the septic tank and/or adjacent absorption elements. Minimum site specific setbacks for system components are: • SourceSe p c Tank Absorption Field Building Sewer • domestic water line 10' 25' 10' • domestic well 50' 100' • domestic water cistern 25' 25' • property lines 10' 10' • unoccupied structure 5' 5' • occupied structure 10' 20' • irrigation ditch • open 50' 50' • intermittent irrigation 10' 25' • gated 10' 25' • solid pipe/lined 10' 10' • To avoid surface flow infiltration and saturation of the new absorption system, abandonment of irrigation in the vicinity of the disposal system is required. Diversion ditches necessary to divert surface flows around the new absorption bed must maintain the minimum setbacks listed above. • All sewer lines and effluent distribution piping shall be 4 inches in diameter and have glued joints. All lines discharging sewage from the structure to the septic tank shall maintain fall of between 1/8 in. and 1/4 in. per foot and shall employ sweep 90's or 2-45's at all turns. Sewer lines from the dwelling to the septic tank and at least 6 ft. from the septic tank outlet must meet minimum standard ASTM-3034. Sewer lines under driveways shall always meet minimum Schedule 40 PVC standards. Additionally, effluent piping in traffic areas with less than 24" of cover shall be encased in 6" CMP or flow fill and covered with minimum 2" high density blue board insulation. • The sewer line shall be encased with minimum 6" PVC with water-tight end caps a minimum of 10' to either side of all domestic water line crossings. 6 • A minimum of 12" of soil cover (18" recommended) shall be maintained over all OWTS components to prevent freezing of septic effluent (excepting septic tank access manholes must extend to the ground surface). • The existing absorption area will be removed. Ali affected soil will be removed and replaced with replacement soil meeting ASTM 33 standard for concrete sand. • The installer shall not place fill in the open excavation until inspected and approved by the design engineer. Additionally, the final cover shall not be placed on sewer lines, septic tank, or the absorption area until the system has been inspected and approved by the design engineer. The installer shall provide 48 hour notice for all required inspections. • Four inch clean outs shall be installed at maximum 100' intervals in all effluent lines exceeding 100' in length. • A non-corrodible Orenco filter (model # FTW0444-36) shall be installed at the final outlet Tee of the septic tank or in the effluent line between the septic tank and the STA to limit the size of solids and sludge passing into the absorption field. The filter must be accessible for cleaning and replacement from the ground surface. • The distribution box shall be set level on undisturbed native soil or a structural pad (e.g., compacted fill or concrete) to prevent settling and promote uniform distribution of flow to the absorption field. A 45 degree bend shall be turned down on the septic influent line to damp surge flows from the septic tank and promote equal distribution. The distribution box must be accessible from ground surface. • The effluent distribution system shall be constructed in accordance with the "Infiltrator Technical Manual" available from Infiltrator Systems Inc., 123 Elm Street, Suite 12, Old Saybrook, Connecticut 06475. • The surface cap shall be mounded 5% over the absorption field to promote surface runoff. • The system contractor shall be aware of the potential for construction activities to reduce soil permeabilities at the site through compaction, smearing, and shearing. The following precautions and construction procedures should be employed during installation to minimize disturbance to native soils: i. Excavation should proceed only when the moisture content of the soil is below the plastic limit. If a sample of soil forms a rope instead of crumbling when rolled between the hands it is too wet and should be allowed to dry before excavation continues. ii. Excavation and backfill equipment should work from the surface where at all practical to avoid compaction of the soils at depth. iii. The bottom and sidewalls of the excavation should be left with a rough, open surface. The appearance should be that of broken or ripped soil as opposed to a sheared, smeared, or troweled surface. Any smoothed or smeared surfaces should be removed with a toothed rake or shallow ripper taking care to remove 7 loose residues from the bottom of the excavation by hand if necessary. iv. Care should be taken in placing fill materials in the excavation to avoid damaging the exposed soil surfaces. 4.2 Operation - Maintenance and Inspections • The owner shall install a structural barrier if necessary and take precautions to prevent vehicular traffic, excessive surface watering, accidental flooding, or other activities in the vicinity of the absorption field which may compact, saturate, or otherwise alter the subsurface soil parameters used in designing the septic system. • The owner will plant and maintain grass or other shallow rooted cover crop to prevent erosion and promote evapotranspiration over the absorption field. • The owner will inspect and maintain the required mounding and drainage away from the absorption field to prevent saturation from precipitation and surface flows. • To mitigate the generation of preferential flow channels which may compromise the operation of the system, the owner will inspect and prevent intrusion of burrowing animals and deep rooted plants into the absorption field. • The septic effluent filter shall be inspected and cleaned as necessary every six (6) months. • The owner will conduct periodic maintenance of the septic system by removing accumulated sludge from the septic tank every 3-4 years to prevent clogging of the absorption field. 8 5.0 Limitations This report is a site specific design for installation of an onsite wastewater treatment system and is applicable only for the client for whom our work was performed. Use of this report under other circumstances is not an appropriate application of this document. This report is a product of CCI Engineering/Cronk Construction Incorporated and is to be taken in its entirety. Excerpts from this report may be taken out of context and may not convey the true intent of the report. It is the owner's and owner's agent's responsibility to read this report and become familiar with the recommendations and design guidelines contained herein. The recommendations and design guidelines outlined in this report are based on: 1) the proposed site development and plot plan as furnished to CCI Engineering/Cronk Construction Incorporated by the client, and 2) the site conditions disclosed at the specific time of the site investigation of reference. CCI Engineering/Cronk Construction Incorporated assumes no liability for the accuracy or completeness of information furnished by the client. Site conditions are subject to external environmental effects and may change over time. Use of this plan under different site conditions is inappropriate. If it becomes apparent that current site conditions vary from those anticipated, the design engineer should be contacted to develop any required design modifications. CCI Engineering/Cronk Construction Incorporated is not responsible and accepts no liability for any variation in assumed design parameters. CCI Engineering/Cronk Construction Incorporated represents this report has been prepared within the limits prescribed by the owner and in accordance with the current accepted practice of the civil engineering profession in the area. No warranty or representation either expressed or implied is included or intended in this report or in any of our contracts. Thomas A. Cronk, P.E. NOTE`:' This ewage disposal plan is meant to include the following four pages of graphics including: 1) plot plan, 2) septic layout plan, 3) absorption field plan view, and 4) absorption field cross section. The plan is not to be implemented in the absence of these related graphics. In addition, results from the percolation test and soils evaluation are included for reference as Appendix A. 9 333.14S0I*42'51T — — 10' utility easement '--- 2303 acres storage yard 1— Ce z - - S89'27'37"J >. adols zE c 2.503 acres storage yard z 0 17- EB 0- V:12 B '®S kk�� M/ -UP >� .c • < _&0 U@2¥x04-2 �ez0_w Oh XD TZ L_• iWI j _1 M(4'— � k 11 \ S drive/parking _ § 0 ado 2 E O LJJZ"/ 26 z� § -3 k 660003§§ |I 3§ §§\ a§§ K -01 / septic - influent • distribution box • absorption field consisting of 3 rows of 13 Ouick4 Standard Infiltrators Car equivalent) for a total of 39 units 52',typ. 6' In. 7010'-12' recommended) 4 \ \ / \ / _ /r) ` — -- / provide inspection/venting ports / at each end of Infiltrator trenches as shown t4B", typ. ABSORPTION FIELD — PLAN VIEW SCALES 1'=10' VISION OIL TOOLS PROJECT 0193 BUD'S WAY, PARACHUTE 2409-273-10-004 ABSORPTION FIELD -PLAN VIEW JANUARY 27, 2015 SCALE I'=10' SYNTHETIC FILTER FABRIC (140-200 MESH) OVER INFILTRATORS, TYP. QUICK 4 STANDARD INFILTRATOR, INSTALL IN ACCORDANCE WITH 'INFILTRATOR TECHNICAL MANUAL, INFILTRATOR SYSTEMS INC., 123 ELM STREET, SUITE 12, OLD SAYBROOK, CONNECTICUT 06475 DISK OR SCARIFY, TYP 46' OF BEDDING SAND MEETING MIN ASTM 33 CONCRETE SAND SPECIFICATIONS SOIL CAP (MOUND 57) PROVIDE VENTING/INSPECTION PORTS AS REQUIRED BY INFILTRATOR INSTALLATION GUIDELINES, TYP. EACH ROW (ONE OF TWO) EXISTING GROUND SURFACE 1 N� 6' MIN,TYP ---�-- 36' ---1 (10'-12' PREFRRED) #1 -12' #2 _72' #3 -120' SOILS LOG (SEE NOTES:: ELEVATION DESIGN SPECIFICATIONS DESIGN DISTANCE FROM SEPTIC TANK TO DISTRIBUTION BOX = 20' ASSUMED ELEVATION OF GROUND SURFACE AT ENTRY TO SOIL TREATMENT AREA = 100.00' ELEVATION DF INFILTRATIVE SURFACE OF SOIL TREATMENT AREA = 97.00' INVERT ELEVATION OF SEWAGE LINE AT EXIT FROM DISTRIBUTION BOX = 97.50' INVERT ELEVATION OF SEWAGE LINE AT EXIT FROM SEPTIC TANK = 97.90' OUTLETS AS REQUIRED 4' 45' -BEND SURGE FLOW SUPPRESSOR1 ABSORPTION FIELD - CROSS SECTION (TYPICAL 3 OF 3) SCALE. 1'=5' 11 =11 11rJ1=1(1Lejl COMPACTED NATIVE SOIL OR STRUCTURAL 1• 'FILL TO PREVENT SETTLING II II�111 n���7-r11 DISTRIBUTION BOX DETAIL SCALE' 1'=1' SOILS LOG NOTES #1 - GRAVEL MANFILL #2 - BROWN SANDY CLAY, MINOR SAND LENSES #3 - LIGHT BROWN SAND/CLAYEY SAND, FRIABLE NO GROUNDWATER AND HIGH SEASONAL WATER TABLE TO 120' BELOW GROUND SURFACE (BGS) VISION OIL TOOLS PROJECT 0193 BUD'S WAY, PARACHUTE 2409-273-10-004 ABSORPTION FIELD - CROSS SECTION JANUARY 27, 2015 SCALE! AS SHOWN APPENDIX A SOILS AND PERCOLATION REPORT CCI ENGINEERING/CRONK CONSTRUCTION INCORPORATED I0 CCI ENGINEERING 1129 -24 Road Cronk Construction Inc. Grand Junction, CO 81505 Grand Junction (970) 245-0577 • Glenwood Springs/Aspen (970) 640-5029 • Montrose/Delta (970) 640-5029 Email: ccid@msn.com SOILS AND PERCOLATION REPORT Date: July 24, 2014 Prepared by: Client: Thomas A. Cronk, P.E. 1129 -24- Road Grand Junction, CO 81505 970-245-0577 Vision Oil Tools 0193 Bud's Way Parachute, CO 81635 970-285-9912 Property address: 0193 Bud's Way, Parachute, CO 81635 Tax schedule No.: 2409-273-10-004 Legal Descript.: 1.0 Soils Evaluation The site consists of approximately 2.50 acres of uncultivated native soil. Drainage varies across the site and is approximately 3% to the south in the area of concern. A percolation test/soils evaluation was conducted on the property of reference on 01/23/15 by Tom A. Cronk, registered professional engineer (R.P.E.). The perc excavation trench (excavation A) was located 60' south of the north property line and 14' east of the west property line. Additional perc holes were located 30' south of the north property line and 25' east of the west property line (excavation B) and 40' south of the north property line and 75' east of the west property line (excavation C). A perc excavation trench (excavation A) was extended to a depth of 120" below ground surface (BGS). There was no evidence of ground water or high seasonal water table in the open excavation to a depth of 120" BGS. The soils evaluation indicates three distinct soil horizons underlie the site. A lithological description follows: depth (in.) description 0" — 12" gravel manfill 12" — 72" sandy clay/minor sand lenses, brown 72" — 120" sand/clayey sand, light brown; friable 1I A visual and tactical evaluation of the site soil and topography indicates the soil horizon below a depth of 12" will provide the optimum soil treatment environment. Perc holes were constructed in excavation A at depths of approximately 4 in., 40 in., and 60 in. Additional perc holes were constructed in excavation B at a depth of 48 in. and in excavation C at a depth of 36 in. Results of the percolation test are shown in Table 1. Depth 13:10 fill (A) 4"-20" 14.25 13:40 15.00 (A) 40"-56" 10.13 (A) 60"-76" (0) 48"-64" (C) 36"-52" 10.25 9.88 10.00 12.13 11.25 11.00 10.75 14:10 15.75 14.13 12.25 12.00 11.50 14:40 16.38 15.88 13.13 13.00 12.06 TABLE 1 Percolation Test Results 0193 Bud's Way, Parachute 14:50 refill 14.25 10.31 10.25 10.50 10.25 Time on 01/24/15 15:20 14.88 12.13 11.06 11.44 10.88 15:50 15.38 13.94 11.88 1231 1144 16:20 15,88 15 69 12.63 13.19 11.94 16:30 refill 14.38 10.75 10.50 10.00 10.38 17:00 14.88 12 44 11.38 10.81 10.88 17:30 15.38 14.13 12.09 11.63 11.38 Time Drop 30/0.50 30/1.69 30/0.81 30/0.81 30/0.50 Perc Rate min/in 60 18 37 37 60 2.0 Limitations This document is representative of the site conditions disclosed at the specific time of the site investigation. Site conditions are subject to change from external events both manmade (irrigation or water feature construction) and naturally occurring (flooding or excessive precipitation). CCI Engineering/Crank Construction Incorporated is not responsible and accepts no liability for any future variation in site conditions. CCI Engineering/Cronk Construction Incorporated represents this report has been prepared within the limits prescribed by the owner and in accordance with the current accepted practice of the civil engineering profession in the area. No warranty or representation either expressed or implied is included or intended in this report or in any of our contracts. 12 Thomas A. Cronk, P.E.