HomeMy WebLinkAboutOWTS Design Report 04.11.2016April 11. 2016
Mr. David Brown
225 N. Mill Street. suite 100
Aspen. Co 81611
PINNACLE DESIGN
CONSULTING GROUP. INC.
OR05 Buck Poi111 Road
Carho11dale , CO 8162 3
(9-0) 963-21-0 Office:
(9-0) 7 0./-0] 15 Fux
RE: LOT 25, STIRLING RANCH -(OWTS) DESIGN
GARFIELD COUNTY, COLORADO
David.
We have completed the design of an (OWTS) system for your Lot located in Missouri Heights.
The design is sized for a 4-bedroom residence and is based on the average percolation rate of 37 MPI as
determined by HP Geotech per their report dated July 25. 2013. (See attached soils investigation for
further information.
Site Conditions:
Based on a review of the survey, and our knowledge of the Stirling Ranch Subdivision. no potable water
wells or irrigation ditches exist within I 00-ft of the proposed (OWTS).
Gravelless chamber trenches have been proposed below the proposed house location on slopes averaging
around 12%, on which standard (OWTS) designs are generally acceptable.
The trenches have been designed based on Soil Type 2A , which determined the design long term
acceptance rate (L TAR) of 0 .5 gallons per square foot per day in accordance with Table 10-1. presented
in the Garfield County, Colorado On-Site Wastewater Treatment System Regulations, adopted April 14,
2014.
Design Calculations:
4 bedrooms =min. 1250-gallon septic tank
Design Flow= 75 gal/day x 2 people/bedroom x 3 bedrooms+ 75 gallon/day 4th bedroom = 525 GPD
LT AR= 0.5 GPO/SF
525 GPO I 0 .5 GPD/SF x 1.0 (gravity trenches) x 0.85 (chambers)= 892.S SF
892.S SF/ 12 SF/chamber= min. 75 'Quick 4' Infiltrator chambers
The OWTS design is based on 4-bedrooms. An average daily wastewater flow of 525 GPD will be used.
The system installation will include a 1250-gallon. two-compartment concrete septic tank with an effluent
filter (or screen) installed on the outlet tee of the septic tank. Effluent will gravity flow to a distribution
box. which must be accessible from grade. Flow equalizers or similar product must be installed on the
outlet of each pipe leaving the distribution box to assure equal flow to each trench.
The final trench design includes five (5) separate trenches with .. Quick-4" Connect Infiltrator Chambers
installed parallel to the site contours, south of the proposed residence. The trenches