HomeMy WebLinkAboutOWTS Design Report 10.19.2022October 19,2022
Lyndsay and Garret Jammaron
4909Highway 82
GlenwoodSprings, Colorado 8 1601
RE:Design Report-Onsite Wastewater Treatment System (OWTS), Jammaron Residence, TBD, Deer Park
Court Glenwood Springs, Sunlight Parkway, Remainder Parcel, M/8, Garfield County, Colorado
SE, Job No. 302105.01 Parcel No: 218534400021, Garfield County Permit:-
Dear Lyndsay and Garuet:
This letter report presents the applicable findings in regard to the design and construction of a new Onsite
Wastewater Treatment System (OV/TS) at the above referenced Site, in support of a OWTS construction permit
application to Garfîeld County. The OWTS design is based on recent site assessment observations by Sopris
Engineering of existing physical site features, conditions and geotechnical soils evaluation with respect to the
proposed residential usage and applicable regulatory design criteria in accordance with State and County OWTS
Regulations. The design recommendations, specifications and construction details are delineated on the attached
OWTS permit/construction plan that was prepared with GIS, Lidar, Survey Plat information and aerial mapping.
The design criteria and system sizing information is summarized below.
Summarv Desiqn Criteria
The new OWTS is designed for a treatment capacity of 600 gallons per day based on the design wastewater flow to
serve a 5-bedroom residence in accordance with Table 6-2 values, Section 43.6, A.4. The OWTS will utilize a new
1,500 gallon 2- compartment and a new 500 gallon 1-compartment, reinforced plastic septic tanks installed in series
adjacent to the proposed driveway within a graded landscape area south of the garagelshop dwelling structure. The
new 1,500 gallon septic tank will be installed with ribbed PVC risers with fiber lids at the surface, inlet sanitary tee,
and an outlet effluent filter sanitary tee. The new 500 gallon septic/dosing tank will be installed with an Orenco
biotube high head effluent pump assembly.
A 1.S-inch schedule-4O effluent transport pipe from the discharge assembly in the septic/dosing tank will be
installed to an automatic distribution valve (ADV) up gradient near the new STA absorption field with individual
1.5-inch schedule-4O distribution pipes installed to a common manifold pipe at the head of 2 paired chamber
trenches.
The soil treatment Area (STA) will consist of leaching chamber trenches that provide 630 S.F. of total absorption
area to be installed at shallow depths not to exceed 30" below existing surface grades. The septic tank effluent will
be pressure discharged through the ADV for alternative dosing of two pairs of the 4 full pressure dosed trenches.
The effluent will be equally distributed along the length of each trench via a custom perforated 1.5-inch schedule-4O
distribution lateral installed on the absorptive surface from the head to the terminal end cap of each trench.
Observation ports with caps will be installed on each end chamber unit. Each terminal end of the distribution lateral
will be capped with a 1.5-inch ball valve centered under the inspection port. 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 (LTAR). The designed system meets all required setbacks and will be installed within the
general location indicated on the plan. The existing onsite well, serving the residence, (DWR Permit No. 268839)
is located over 175 feet southwest of the proposed field area. Our design is outlined below and delineated on the
attached C-6.0 OWTS plan.
502 Main Street a Suite A3 a Carbondale, C0 81623 a 970 704-031 1 Fax (970) 704-031 3
SoPRrs tttcmttnIlG o 11G civil consultants
L1'ndsay And Garret Jammaron Residence
OV/TS, TBD, Deer Park Court Glenwood Springs
SE Job No. 32105.01
October 19,2022
Page2
Desisn FIow
The design flow is calculated as follows for the total curent and design waste flows of the existing single family
dwelling. The OWTS is designed for a treatment capacity of 600 gallons per day based on the design wastewater
flow to serve a 5-bedroom capacity residence in accordance with Table 6-2 values, Section 43.6, A.4. Regulation
43:
Minimurn 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 7 5 gallperson/day.
Design flow (Qd)gallons/day: (# of people) x (avg. flow)gallperson/day.
Design flow Qd:8*75:600 gpd
Septic Tank Desisn
The septic tank capacity required for a minimum 48 hour retention time is calculated as follows:
V:600 gallday * 2= 1200 gallons.lnstall a 1,5OO-gallon,2-compartmentand a 5OO-gallon l-compartment
reinforced plastic septic tanks installed in series for a total tank capacity of 2,000 gallons. The 5OO-gallon
septic/dosing tank will be equipped with a biotube effluent pump vault.
Sub Surface Conditions and Observation
A subsurface soil investigation and site assessment was performed by Sopris Engineering on April 14,2022.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 pits in the
building envelope and one profile pit in the proposed OWTS field area. The soils below 6 to 9 inches of topsoil
consist of medium dense sandy silt loam soil with less than 2%o scattered gravel or rock content to 7 feet below the
surface grades. The soils appear to be consistent across the site from observations in the excavated profile pits.
The native soils sampled from 2-3 feet below the surface are characterized as a soil type 2 consisting of sandy silt
loam texture with blocþ granular structure. This soil has an effective loading rate for conventional soil treatment of
0.6 Gal/S.F.iday for a level I conventional treatment system. The equivalent percolation rate is assumed to be 20-30
minutes per inch. No free water was encountered in excavations on site. Seasonal high Groundwater levels are
expected to be below 20 feetfrom the existing surface grades. The soils are suitable for a conventional shallow
absorption field consisting of pressure dosed gravelless infiltration chamber units in a trench configuration.
Additional observations and soil evaluation will be performed during construction, by Sopris Engineering in the
area of the proposed absorption fîeld to confirm the previous soil evaluation. Sopris Engineering will observe new
profile pits in the area of the proposed absorption field to veri$ the in-situ native soil's characteristics. If soil
conditions encountered require adjustments to design criteria or the design plan, notice will be made to County
EHD and applicable revisions to design/construction plans and report will be submitted. The results of the
additional soil evaluation and soil characterizationwill be included in the As-Constructed documentation.
Treatment-Soil Treatment Unit/ Absorption Svstem Design
The treatment/absorption field is designed based on utilizing the effective Long Term Acceptance Rate (LTAR) for
the native soils and the application of appropriate loading factors for a soil treatment area system utilizing pressure
distribution to full pressure dosed gravelless chamber trenches. The new treatment system and absorption field will
consist of pressure dosed distribution of septic tank effluent from a biotube high head pump assembly vault to an
automatic distributing valve with individual distribution pipes routed to each paired chamber trench installed with
custom perforated distribution laterals. Each of the paired trenches will be alternately dosed with equal distribution
across the native soil absorptive surface.
Lyndsay And Garret Jammaron Residence
OWTS, TBD, Deer Park Court Glenwood Springs
SE Job No. 32105.01
October 19,2022
Page3
The shallow STU trenches shall be installed with a maximum depth to the absorptive surface of 36" inches from
finish surface grades and backfilled with approximately 3-inches of final grading topsoil over the trenches placed to
allow positive drainage away from the surface. Chambers shall be installed level in native soil over the scarified
absorptive surface at the bottom of each trench excavation. Each trench will be constructed level with minimum
exaction depths. A minimum separation distance of 4 feet will be maintained between the individual trench
sidewalls.
The engineer, prior to installation shall inspect the trench excavation to confirm soil conditions and installation
procedures. For colder weather installation, all excavation, component placement and initial backfill should be
performed in dry weather conditions and any segments of trenching should be substantially completed prior to any
precipitation event. It is recommended that exposed chambers be backfilled as soon as possible to prevent any
rainlsnow from accumulating in the open trenches. Terminal ends should be left exposed for final inspection by
engineer. The installer shall photo document the installation of trench components prior to backfill of any trench
segment. All septic system components and trench installations are to be approved by the Engineer prior to
backfilling.
Field Sizing:
Receiving Wastewater Treatment Level 1; Soil type 2loading rate for a sandy silt loam is (0.6 gal./S.F./day).;
Loading factors; (Table 10-2, pressured dosed trenches:0.8 ) and
(Table 10-3, Chambers Category 3 = 0.7)
A(sÐ Qd x L.F.l x L.F.2 .
LTAR
A: Area;
LTAR: 0.6 Gal/S.F.lday for silt loam
Qd: flow (gal/day):600 gpd
L.F.1:0.8 full pressure dosed trenches Distribution
L.F.2:0.7 Chambers Category 3
A(sÐ:600 epd x 0.8 x 0.7:560 S.F
0.6 Gal/S.F.iday
Nurnber of Quick-4 Infi ltrator chambers 4' x3' x7 2" chambers :
560 S.F : 47 Infiltrator Quick-4 chambers; Use 52 chambers
12 S.F./Chamber
Number of 5'x3' Bio-Diffuser chambers:
560 S.F :37 chambers; Use 42 chambers
15 S.F./Chamber
STU Layout
Use 72 Quick-4 Infiltrator chambers in four trenches 74'longby 3'wide with 18 chamber units per trench plus two
end caps as delineated on the plan or equivalent Arc/Bio-Diffuser chamber trenches. The septic tank effluent will be
pressure distributed to the head of each chamber trench via individual distribution pipes from an automatic
distribution valve.
Use 52 -Diffuser chambers in four trenches 54' long by 3'wide with 13 chambers units per trench plus two end
caps as delineated on the plan or equivalent Bio-Diffuser chamber trenches. The septic tank effluent will be
Lyndsay And Garret Jammaron Residence
OWTS, TBD, Deer Park Court Glenwood Springs
SE Job No. 32105.01
October 19,2022
Page4
pressure distributed to the head of each chamber row via individual distribution pipes from an ADU pressurized by
a high head pump biotube discharge assembly in a the 500 gallon dosing tank.
Effluent Distribution System
The OWTS field shall be fully pressure dosed along the entire length of each trench. An Orenco Systems Bio Tube
pump vault system will be installed with an effluent screen in the septic/dosing tank. The pump systern shall
incorporate a single high head pump. The simplex pump assembly will demand dose effluent through a single 1.5-
inch diameter PVC transport pipe frorn the pump assembly and connect to a two outlet ADU (Model 6402) valve
housed in a ribbed PVC riser. The ADU must be installed with the inlet pipe at a high point relative to the discharge
assembly outlet and the individual distribution pipe connections to the manifold pipe at the head of each zone set of
paired trenches. The 1.5" discharge transpot't pipe shall be installed with a minimum 2.5Yo continuous slope to
allow for drainage of the pipe back to the pump vault.
The effluent will be alternately equally pressure dosed through each 1.S-inch custom perforated distribution lateral
running the length of the trench installed on the absorptive surface centered below the chambers. The distribution
laterals will have 5/16-inch orifices drilled every 2.0 feet oriented upward to spray against the interior chamber
units. The first and last orifice will be drilled and oriented downward with an orifice shield to allow drainage of the
line. Individual 1.5-inch ball valves will be installed at the end of each perforated distribution lateral centered below
one of the end cap vertical inspection port penetratiorrs at tlte terntitral end of the field. A vertical 4-inch inspection
port will be installed from an end cap inspection port penetration at the terminal end of each trench and one 4-inch
inspection port will be installed from a end cap penetration at the head of each trench. All inspection ports shall
extend a minimum 2-inches above the finish grade and be topped with a pipe cap.
Pump operations shall be controlled by a pedestal mounted exterior control panel in close proximity with tlirect line
of site with the tank. Automatic float switches for on, off and high water with alarm activation shall be installed on
a dedicated PVC float tree. Two separate circuits from the electrical circuit panel and/or junction box shall be
routed to the control panel for separate power to the controls and pump.
Construction and Inspections
Prior to construction of the permitted system, the engineer should be contacted by the contractor and owner to
discuss the system components with the contractor, answer questions, resolve any conflict issues and schedule
inspection site visits based on construction progress. A pre-OWTS construction meeting is essential and required
prior to installation of the OWTS. All septic system components shall be staked in the field for approval by the
Engineer prior to excavation.
During construction the engineer will consult with installer regarding installation procedures and schedules, review
photographs and attempt to perform timely inspections daily to allow for backfilling during cold weather conditions.
All septic system componcnts and trench installations are to be approved by the Engineer prior to backfilling. All
installation will be inspected, fîeld measured, reported and delineated in the Certification lcttcr and rccord drawing.
The contractor nccds to photo document all OWTS construction phases and supply photos to the Engineer on a
daily basis.
County Regulations require that the Engineers of record perform site inspections of the permitted system during
construction and provide "As-Builf' documentation of the installed system to the County after construction is
complete. With respect to r":oltl weaúrer ancl/or winter cr:nditious efforts to allow county inspection of installed
component prior to final backfill shall be coordinated to the extent possible.
Lyndsay And Garret Jammaron Residence
OWTS, TBD, Deer Park Court Glenwood Springs
SE Job No. 32105.01
October 19,2022
Page5
OWS Oneration and Illaintenance
Ownership of the system and responsibility for maintenance and repair will rernain with the property Owner. The
Owner is encouraged to retain the servicçs of qualified personnel to inspect the OWTS dosing and distribution
systems atrd to perform all maintenance and repairs necessary to ensure that the system components are maintained
in good operating condition. The tanks and freld system should be inspected and maintained as needed. Suitable
vegetative cover should be re-estabtished in the freld area, The components of the OWTS system should be
inspected within 14 days of being placed into operation, again in early spring and thereafter should be 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 problerns. In general, for a properly utilized system, septic
tanks should be pumped every 3 - Syears. The effluent fìlter and pump fìoats should be cleaned every six months
and at the tirne of tank pumping. Absorption fields should be maintained with suitable vegetative cover and kept
free of root invasive plants. Positive surface drainage away from the absorption freld should be maintained.
If you have any question or need any additional information, please call.
Sincerely,
SOPzuS ENGINEERING, LLC
PaulË. Rutledge
Design Engineer Principal
'&t q7 2t¿?
28377