HomeMy WebLinkAboutOWTS Treatment System Planning 01.11.17ALL
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Four Wheel Drive Rd
Carbondale, CO 81623
970-309-5259
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January 11, 2017
Julie Pratte
The Land studio
jjpratte@comcast.net
Onsite Wastewater Treatment System Planning
Proposed Subdivision of Property
3064 Cattle Creek Road
Garfield County, Colorado
Julie,
Project No . C1222
ALL SERVICE septic, LLC has reviewed the desired development plan and visited the subject property to
assess onsite wastewater treatment system (OWTS) alternatives for a proposed subdivision of the
property. The 10.95-acre property is located outside of Glenwood Springs , in an area where OWTSs and
wells are necessary. We have made some additions to the analysis, as requested by Garfield County
Planning Department. The initial OWTS planning packet dated August 28, 2016 should be discarded and
replaced with the documents dated January 11, 2017 .
Legal Description: Section: 10 Township: 7 Range : 88 TR IN LOT 14 CONT 10.0AC ALSO A TR CONT
.95AC
Parcel ID: 2393-103-00-047
EXISTING CONDITIONS
A 4-bedroom, single-family residence is currently developed on the eastern portion of the property. This
residence is served by an OWTS designed by ALL SERVICE septic, LLC in 2008, Project No. 1532. This
OWTS consists of one 1500-gallon concrete septic tank with a pump in the second compartment.
Effluent is pumped to four rows of 14 'Quick 4' Infiltrator® chambers. Please note the location of the
existing OWTS as located on the previous High Country Engineering site plan was incorrect. The
enclosed site plan indicates the coffect location of the existing OWTS. The soil treatment area (STA) is
located to the east of the existing driveway.
PROPOSED DEVELOPMENT
It is proposed that the property be subdivided, dividing the property from north to south. A 4-bedroom,
single-family residence on the western portion of the property is contemplated.
Page 2
We have calculated approximate sizing of an owrs that would serve the proposed future development
assuming Soil Type 2 with a long term acceptance rate (L TAR) of 0.6 gallons/square foot (based on
percolation tests and soils data obtained from ALL SERVICE septic, LLC documents dated 2008,
enclosed).
We recommend the STA consist of pressurized gravelless chamber trenches because of the higher level
of treatment obtained by this type of application versus a gravity fed ST A Pressure dosing and
chambers will allow a reduction in total square footage of the ST A Garfield County requires a
Professional Engineer design any OWfS that utilizes a pump.
Design Calculat ions: sro~a()t<\ 5 : 3<\'3o ,1t; C:Oc..\\onsjc\c..'\
4 -bedrooms = 525 GPO :s S~ "".. 0
525 GPO I 0 .6 gal /SF = 875 SF ~q'-1/.fo = <o.5 7
875 SF x 0.8 (pressure dosed trenches) x 0.7 (chambers)= 490 SF
490 SF/ 12 SF/chamber= 41 chambers
The OWTS may include a minimum 1500-gallon, two-compartment septic tank with a pumping system in
the second compartment of the septic tank. The soil treatment area (STA) may consist of three
trenches, each consisting of 14 'Quick 4' Infiltrator® chambers for a total of 42 chambers and 504 square
feet of infiltrative area. There must be at least 6-feet of undisturbed soil between each trench.
This would result in an approximate footprint of 21' x 56'.
Alternative designs may be considered. If assumptions about the soil type are found to be incorrect or if
design configuration or technology choices are modified, the footprint of the STA is subject to change.
Minimum setback requirements to any OWTS component must be considered .
House to ST A = 20 feet
STA to unlined irrigation ditch = 50 feet
STA to lined ditch = 1 O feet
STA to well= 100 feet
Septic tank to well = 50 feet
OWTS Component to property line = 1 O feet
There are two primary lateral ditches and multiple off-shoots within 50-feet of the possible locations for
the proposed ST A One primary ditch runs approximately 35-feet south of the northern property
boundary and the other within 10-feet of the west property boundary on the adjoining property to the
west1 .
1 This ditch is located on the adjoining property to the west. Lining or placing this ditch in a culvert will require
permission from the property owner.
Page 3
If placement of the STA encroaches on the minimum required 50-foot setback, the ditch(es) must be
lined or placed in a culvert. We have indicted the potential length of the ditch that may need to be lined
or placed in a culvert, depending on the location of the STA, in the enclosed site plan. Option #1 entails
lining of both the northern and western laterals for a total of approximately 390-feet (indicated in
YELLOW). Option #2, considering placement 50-feet south of the northern lateral, would require lining or
placing the western lateral in a culvert for approximately 175-feet (indicated in GREEN).
The exact location or footprint of the residence has not yet been determined . Once placement of the
house is finalized, this will dictate placement of the OWTS components, and all setbacks will be
considered and outlined in the OWTS Design documents which will be used in conjunction with an
OWTS Permit issued by Garfield County at the time of Building Permit issuance.
Please call with questions.
Sincerely,
ALL SERVICE septic, LLC
Carla Ostberg, MPH, REHS