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HomeMy WebLinkAboutObservation of Installation 03.18.25March 18, 2025 502 Main Street • Suite A3 • Carbondale, CO 81623 • (970) 704-0311 • Fax (970) 704- 0313 S OPRIS E NGINEERING • LLC civil consultants Garret and Lyndsay Jammaron 4909 Highway 82 Glenwood Springs, Colorado 81601 RE: As-Constructed Report–Onsite Wastewater Treatment System (OWTS), Jammaron Residence, TBD, Deer Park Court Glenwood Springs, Sunlight Parkway, Remainder Parcel, M/B, Garfield County, Colorado SE Job No. 302105.01 Parcel No: 218534400021, Current Garfield County OWTS Permit# SEPT-7879 Dear Garret: Pursuant to County requirements, this letter provides documentation that the Onsite Wastewater Treatment System (OWTS) components recently installed at the above referenced site is in compliance with the permitted design as designated by the change order to the OWTS construction permit (SEPT 7879 Issued 11/04/2022) and reissued on 03/13/2024. Sopris Engineering inspected the excavations, soils, materials and the installation of the system components during construction, prior to final backfill and after all installations were completed. The new OWTS included a plastic detention tank, an effluent dosing tank, dispersal dosing/distribution components, sand filter absorption field and controls. The system is designed to treat the total combined wastewater design flow of 600 gpd for the shop/2-bedroom ADU and future 3- bedroom residence based on an equivalent 5-bedroom residential capacity. Sopris Engineering performed site visits to inspect and document the as-constructed conditions of the OWTS. Inspections were coordinated with the property owner and the contractor, Cx2 trucking LLC., that installed the system components. The as-constructed conditions and installation of the OWTS components is in compliance with Garfield County regulations. The installed system with specifications is delineated on the attached As-Constructed OWTS Record Drawing dated 03-17-2025, by Sopris Engineering. Final inspection and System Startup Sopris Engineering performed a site visit on February 19, 2025, to inspect and check operational function of the recently installed OWTS. SE inspected the OWTS to complete the required As-Constructed record drawing, certification letter and to document that all previously listed Final Inspection Punch list items were addressed pursuant to the email by Garfield County, Julia Lee, dated 11-18-2024. Sopris Engineering checked the float setting and performed a dry run system startup to test float and control operations on February 19, 2025. The system floats were found to be wired for correct functionality in compliance with control panel installation and design performance specifications. No significant water was in the dosing tank at the time, however the floats were manually operated to test the pump on/off activation and to confirm that the high water visual/audible alarm is active. The floats were set per the original design intent performance specifications with respect to the field adjusted tank, piping and STA configuration as-constructed conditions. The updated performance calculations are presented on the Record drawing. The dosing volume is approximately 55 gallon per cycle and the distal end of lateral orifice head is 36”. The testing verified that the system is functioning as designed and can be set for automatic normal operation once normal liquid level (36”) is in the dosing tank. The pump amperage and voltage was tested and found to be in compliance with manufacturer’s specifications. AC OWTS, Jammaron Residence Deer Park Court Glenwood Springs SE Job No. 32105.01 March 18, 2025 Page2 County Punch List Items The following punchlist items were specifically considered during the Engineer’s inspection and in coordination with the contractor to prepare the As-Constructed Record Drawing. Final grading around installed tank risers and adjacent vicinity of drive and field will be performed in early spring by the contractor that will include the permanent setting of all observation and flush assembly valve boxes. The engineer will perform a followup inspection as needed with the contractor. Currently the system is installed and will operate as designed and is in compliance with the regulations. Sewer line: • Previous photos of sewer line installation showing location of all 45-degree bends. Installed a single 45-degree and 22-degree bend as shown on the AC Record drawing. • 2nd double sweep cleanout within 100 ft of the 1st cleanout outside the building. Installed intermediate 2-way cleanout 98 ft from the first cleanout, (See AC dwg and photo set). • Remaining portion of sewer line connection still to be installed. Installed all sewer service piping, (See AC dwg). Tank(s)/ Pump: • Tank inlet and outlet Ts Installed tank inlet sanitary tee and effluent filter outlet tee, (See AC dwg and photo set). • Effluent filter installed in outlet T with handle that extends to within 12 inches of final grade. Installed effluent filter with handle • Effluent line to pump chamber. Installed 4” effluent pipe from primary septic tank outlet to inlet dosing tank. • Control panel within sight of pump. Installed Orenco S-1 control panel approximately 5’ from dosing tank access lid, (See AC dwg). • Video showing visual and audio high water alarms on pump control panel. Engineer testing and observation confirmed active visual and audio high water alarms • Splice box installed outside riser with connections using blue (watertight) wire nuts. Installed splice box and wire nuts as specified, (See AC dwg and photo set). • Screened pump chamber and all connections. Installed biotube pump/filter/discharge assembly as specified, (See AC dwg and photo set). • Watertight risers installed to bring tank access for both tanks to final grade. Installed watertight risers necessary for lids to be at finish grade, (See AC dwg and photo set). Effluent line and STA: • Pressurized effluent line Installed 1.5” schd-40 transport pipe to from discharge to manifold pipe, (See AC dwg). • Flushing valves at ends of all distribution laterals Installed 1.5” ball valves on ends of distribution laterals, (See AC dwg and photo set). • Installation of all chambers (45 Quick4's minimum) Installed 45 Quick 4+ chambers with end caps in 3 rows of 15, (See AC dwg and photo set). • Chamber end plates with inspection ports (inspection ports must be in the four corners of the bed at minimum) Installed 4” inspection ports on all chamber end caps. End cap inspection ports will be cut down slightly below grade and housed in valve boxes with lids at finish grade along with the corner inspection ports this spring when contractor returns to site this spring to perform final grading around tank risers and vicinity. AC OWTS, Jammaron Residence Deer Park Court Glenwood Springs SE Job No. 32105.01 March 18, 2025 Page3 As-Constructed OWTS Tanks and Treatment Field The OWTS utilizes a new 1,500 gallon 2- compartment and a new 500 gallon 1-compartment, reinforced plastic septic tanks that were installed in series to the southwest of the dwelling and auto. The 500 gallon septic/dosing tank was installed with an Orenco biotube high head effluent pump assembly. A PF3005 pump with PVU 1819 biotube pump vault was installed. A 62.5' long by 12' wide slightly mounded pressure dosed sand filter bed was installed with individual custom perforated distribution laterals, configured in three rows placed on the surface of the 24-inch deep sand filter media. The 12-feet width of sand media is contained on the sloped terrain by placement of a 2- 2.5 foot high embankment, on the down gradient perimeter, consisting of native excavated soil material placed over the grubbed native soil along the down gradient perimeter of the bed to the specified height of 18-inches above the top of sand level. Effluent Distribution System Filtered effluent will discharge to the bed laterals via a 1.5 inch diameter transport pipe from the high head pump biotube discharge assembly to the common distribution piping manifold connecting each perforated lateral row at the head of the sand filter bed. The transport pipe tee fitting connection on the manifold pipe is set at a highpoint invert approximately 2” above the invert of the manifold pipe to insure drainage into the manifold and laterals. The discharge assembly has an anti-siphon orifice to allow for complete drainage of transport pipe after each dosing cycle. The effluent is equally pressure dosed through each 1.5-inch custom perforated distribution lateral that was installed with 5/32-inch orifices drilled every 2.5 feet oriented upward to spray against the interior chamber units. The first and last orifice are drilled and oriented downward with an orifice shield to allow drainage of the lateral. The 1.5” PVC distribution laterals are covered with 15 Quick-4 LP chambers per row acting as spray shields to effectively distribute effluent over the infiltrative surface. The sand and chamber units are covered with non-woven filter fabric, (Mirfi N-140 or equivalent). The entire bed was backfilled with native soil 8 to 12 inches above the top of chambers. The sizing is based on a design flow and treatment level-3 LTAR loading rate for in-situ receiving soils utilizing a minimum 24-inch depth of secondary sand filter media placed above the native soil interface. Observation ports with caps were installed on each end chamber end cap. Piezometer inspection ports placed on each corner of sand bed. The distal ends of the distribution laterals are capped with a 1.5-inch ball valve housed in a valve box. End cap inspection ports will be cut down slightly below grade and housed in valve boxes with lids at finish grade along with the corner inspection ports this spring when contractor returns to site this spring to perform final grading around tank risers and vicinity. The system was installed in compliance with the permitted OWTS design intent and regulatory criteria. The completed system is setup to operate pursuant the established effluent dosing performance specifications with respect to the as-constructed conditions as delineated on the attached C-3.1 As- Constructed OWTS plan. AC OWTS, Jammaron Residence Deer Park Court Glenwood Springs SE Job No. 32105.01 March 18, 2025 Page4 Design Flow The OWTS was designed for a treatment capacity of 600 gallons per day based on the design wastewater flow to serve an equivalent 5-bedroom residence in accordance with Table 6-2 values, Section 43.6, A.4. Regulation 43: Minimum population based on 2 person per bedroom for the first 3 bedrooms = 6 persons and 1 person per bedroom for each additional bedroom = 2 persons for a total of 8 persons at 75 gal/person/day. Design flow (Qd) gallons/day = (# of people) x (avg. flow)gal/person/day. Design flow Qd = 8*75=600 gpd Septic Tank Design The septic tank capacity required for a minimum 48 hour retention time was calculated as follows: V = 600 gal/day * 2 = 1200 gallons. A 1,500-gallon, 2-compartment and a 500-gallon 1-compartment reinforced plastic septic tanks were installed in series for a total tank capacity of 2,000 gallons. The 500- gallon septic/dosing tank was equipped with a biotube effluent pump vault. Sub Surface Conditions and Observation A subsurface soil investigation and site assessment was performed by Sopris Engineering in on April 14, 2022 in the original proposed OWTS field location up gradient northeast of the dwelling structure. A new subsurface soil investigation and site assessment was performed by Sopris Engineering in on November 12, 2024 in the vicinity of a proposed alternate preferred OWTS field location cross gradient west of the shop/dwelling structure currently under construction. The soils in the proposed field envelope area were sampled and characterized by application of the USDA visual/tactile soil texture method analysis. The subsurface conditions were evaluated by excavation of two exploratory profile pits (4 & 5) in the new location of the proposed OWTS field area. The soils below 6-inches of topsoil consist of dense sandy silt loam soil with less than 5% scattered gravel or rock content to 5 feet below the surface grades. Soils below 5 feet are increasingly rocky and are characterized as Type R1 soils with rock content greater than 35% and less than 65% with 50% of the rock content size less than 3/4 inch. The rocky soils at depth have an effective loading rate for of 0.8 Gal/S.F./day for a level 1 treatment system. Soils below 7 feet become more resistive due to the presence of denser rock. Due to dense soils at depth and to provide optimal treatment an intermittent sand filter was recommended to provide for a treatment level TL3 sand filter system. No free water was encountered in excavations observed on site. Perched Groundwater levels are expected to be below 7 feet from the existing surface grades. The native soils sampled from 2 to 3 feet below the surface are characterized as a soil type 2A consisting of sandy silt loam texture with massive to granular structure. This soil has an effective loading rate for conventional soil treatment of 0.5 Gal/S.F./day for a level 1 conventional treatment system and 0.90 gal/S.F./day for level 3 enhanced treatment. The equivalent percolation rate is assumed to be 25-40 mpi. The soils are suitable for the installation of a sand filter treatment bed system consisting of a minimum 24" depth of secondary sand Media that will be fully pressure dosed meeting the requirements under sections (43.10.C,D,E,F&H and 43.11.C.).