HomeMy WebLinkAboutOWTS Design Report 06.19.17
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826 ½ Grand Avenue, Glenwood Springs, CO 81601
P: 970.945.5544 F: 970.945.5558 www.mountaincross-eng.com
June 19, 2017
Red Barn Guest Ranch
C/O Mr. Larry Halonen
26432 El Mar Drive
Mission Viejo, CA 92691
RE: Red Barn Guest Ranch, 345 Mid Valley Lane, Newcastle, CO – OWTS Report
Dear Larry:
The purpose of this correspondence is to inform you about the onsite wastewater treatment system
(OWTS) designed for the Red Barn Guest Ranch. The project proposes to construct a reception
center for events serving up to 300 people. The project is located in Peach Valley, to the east of
Silt and to the west of New Castle, at 345 Mid Valley Lane. This will be a gravity system from
the events center to a conventional septic tank where a siphon doses to a leach field comprised of
infiltration chambers. The event center will be served by well water. The OWTS is not within the
100-year flood plain boundary. There are practical constraints that you should be aware of when
considering the proper design, construction, and operation of the OWTS.
Subsurface
The LTAR value was approximated as 0.60 gallons per day per square foot (GPD/sq.ft.) from soil
evaluations as a sandy loam, silt loam and also from percolation test results performed by this
office on June 14, 2017. These percolation tests results yield a value of 24.7 minutes per inch. An
8’ deep profile hole was excavated and an inspection revealed that no bedrock or high groundwater
table is within the leaching area.
Design Calculations
The water use is based on a flow rate of 5 gallons per person per day. Using Garfield County
Table 6-2, this equates 1,500 gallons per day (GPD) total. The design calculations for sizing of
the septic system and the leach field follow:
Red Barn Guest Ranch: 300 Person Capacity * 5 GPD per person = 1,500 GPD
Based on soil evaluation and percolation tests results, LTAR = 0.60
Minimum absorption area = 1,500 GPD / 0.60 = 2,500 sq. ft.
Reduction in soil treatment areas for chamber/trench treatment with dosing
= 2,500 sq. ft. * 0.7 * 0.9 = 1,575 sq.ft leach area
Required chambers = (1,575 sq.ft)/(12.34 sq.ft/chamber)
= 127.6 chambers, Use seven rows of 19 chambers, 133 chambers
Required septic tank volume = 2,000 gallons per Garfield County Table 9-1
Red Barn Guest Ranch
June, 2017
Page 2 of 3
Mountain Cross Engineering, Inc.
Civil and Environmental Consulting and Design
826 ½ Grand Avenue, Glenwood Springs, CO 81601
P: 970.945.5544 F: 970.945.5558 www.mountaincross-eng.com
The components manufacturers are typical for the area. Alternatives may be considered by
contacting this office. Construction must be in accordance with the specifications of Garfield
County Environmental Health, the OWTS permit, and this design.
Topsoil should be placed over the OWTS and planted with native grasses. No large vegetation
and/or plants with taproots should be planted over the absorption area nor grasses that require
excessive irrigation.
Setbacks
The location for the septic and dosing tanks are limited by setback requirements per Garfield
County and the State of Colorado. These include:
50’ FROM WELL
10’ FROM WATER SUPPLY LINE
5’ FROM BUILDING
10’ FROM PROPERTY LINE
10’ FROM LINED DITCH OR STREAM
50’ FROM STREAM
5’ FROM LEACH FIELD
The leach field setback requirements are:
140’ FROM WELL
25’ FROM WATER SUPPLY LINE
20’ FROM BUILDING
10’ FROM PROPERTY LINE
10’ FROM LINED DITCH OR STREAM
90’ FROM UNLINED DITCH OR STREAM
5’ FROM SEPTIC TANK
The setback requirements deal primarily with buildings and potential contamination from the
septic tank, dosing tank, and leach field to either culinary water or surface water. These setbacks
have been included on the plans for reference.
There is a proposed pond that will need to be either lined or the shape of the pond modified to
conform to the required setbacks. Additionally, the Ware and Hinds ditch is an unlined ditch. The
leach field will need to be located out of the required setback distance.
Operation Information and Maintenance
The Owner will need to be responsible for the operation and management of the OWTS. Geo-
fabrics or plastics should not be used over the absorption area. No heavy equipment, parking of
machinery, or materials should be placed on the absorption area. Livestock should not graze on
the absorption area. Plumbing fixtures should be checked to ensure that no additional water is
Red Barn Guest Ranch
June, 2017
Page 3 of 3
Mountain Cross Engineering, Inc.
Civil and Environmental Consulting and Design
826 ½ Grand Avenue, Glenwood Springs, CO 81601
P: 970.945.5544 F: 970.945.5558 www.mountaincross-eng.com
being discharged to OWTS; for example, running toilets or leaky faucets can discharge hundreds
of gallons of water a day and harm the absorption area.
Garbage disposal use should be minimized, and non-biodegradable materials should not be placed
into the OWTS. Grease should not be placed in drains and grease traps should be installed
upstream of the septic tank but downstream from any kitchen. Loading from a water softener
should not be discharged into the OWTS. No hazardous wastes should be directed into the OWTS.
The OWTS is engineered for domestic waste only.
The Owner will likely need to contract with a septic system cleaner to clean the septic tank every
two years, or as needed gauged by measurement of solids in the tank. The standards of
performance for the septic system cleaner are recommended to be the following, at a minimum:
1. The Systems Cleaner shall be licensed.
2. The Systems Cleaner, when cleaning a septic tank, shall remove the liquid, sludge, and
scum, leaving no more than three (3) inches depth of sewage in a septic tank.
3. The Systems Cleaner shall maintain his equipment so as to ensure that no spillage of
sewage will occur during transportation, and that its employees are not subject to undue
health hazards.
4. The Systems Cleaner shall dispose of the collected sewage only at a designated site
recognized by the Board of Health.
Construction Observation
Prior to being backfilled, the construction of the OWTS and all of the components will need to be
observed by representatives of Mountain Cross Engineering, Inc.
The conclusions and opinions that are expressed above are based on the information available at
the time of preparation of this report. Any additional information presented afterward may require
that these opinions and the design be modified.
Thank you for the opportunity to provide this report. Feel free to call if you have any questions,
concerns, or comments.
Sincerely,
Mountain Cross Engineering, Inc.
Chris Hale, PE