HomeMy WebLinkAboutOWTS PlansJuly 23, 2020
Mr. Ted White, PE
Environmental Health Specialist III
Garfield County Public Health
2014 Blake Avenue
Glenwood Springs, CO 81601
RE: Lee OWTS
0789 CR 202
Debeque, Colorado
OWTS Replacement Design
Dear Ted,
The purpose of this letter is to transmit the design regarding the onsite wastewater treatment system
(OWTS) for Robert Lee located on High Lonesome Ranch at 0789 CR 202, Debeque, Colorado. The
property is accessed by Kimball Creek Road (CR 202) just after the road crossing of Roan Creek, north of
Debeque, Colorado. The existing system is failing, and it appears that the existing system was a “bed”
constructed in 2003. The bed size, as determined under the prior code, is 676 sf. It appears to be served
by an existing 1250‐gallon concrete septic tank in is a gravity fed system. The specific location of the
property in question is located in Figure 1.
Figure 1 ‐ Vicinity Map
Property Location
Kimball Ck. Road
Roan Ck.
www.s gm-inc .com
GLENWOOD SPRINGS 118 West Sixth St, Suite 200 | Glenwood Springs, CO 81601 | 970.945.1004
This replacement onsite wastewater treatment system is intended to continue to serve the existing four
bedroom modular home. As you will see on the schematic drawings and information attached, the home
is provided with a gravity service from the home to a 1,250 gallon septic tank that is presumed to be a
precast concrete septic tank (based upon installation records from the County). From the septic tank, the
effluent supernatant is transported to a proposed distribution box followed by the Infiltrator Quick4
trench disposal system. Each of the five proposed trenches is to be 84 feet long with 21 Quick4 Infiltrators
to comprise the system. Standard end caps are proposed on the end of each trench along with air vents
serving as inspection ports. The piping from the distribution box and infiltrator trenches shall be a
minimum diameter of 4” ASTM 3034 PVC. Locations of the existing tank, new distribution box and
infiltrator trenches is specified in the attached drawing plan of this package in an area located just south
of the existing building honoring property line, building, creek and well setbacks.
During soils testing, no groundwater or bedrock levels were found to exist within 8’ of the ground surface
(ie., 4 ft. of the bottom of the proposed infiltrators). The overburden soils were consistent and appeared
to be a silty clay/silty clay loam material consistent with soil types 3 and 4 identified in Garfield County
OWTS Regulations Table 10‐1.
Research was performed to gain insight on the specific soils parameter utilizing the NRCS WebSoil survey.
The sampling and tactile soil analysis determined for design appears to be consistent with the Panitchen
Loam identified in the NRCS WebSoil Survey. The exhibits attached to this letter identify both the
information that was researched in addition to the testing performed to help determine the LTAR (Long
Term Acceptance Rate) for the STA (Soil Treatment Area) for the design of the new disposal field and the
OWTS Design with installation details.
Exhibits are listed as follows:
1. Exhibit A: NRCS Physical Properties Report
2. Exhibit B: SGM Tactile Soil Analysis
3. Exhibit C: OWTS Design and Details
Based researched data, the LTAR for the on‐site soils is 0.275 gallons per day per square foot. With this
data, the STA (Soil Treatment Area) is 1,909 square feet. Because we will incorporate the use of
Infiltrators chambers, we have employed the size adjustment factor and reduced the trench size by the
following:
For using chambers, a 0.7 factor is applied, thus resulting is an area of 1,336 sf. This results in five
infiltrator Quick4 chamber trenches of dimension 92’ in length. The attached calculations identify the
thought process in the design of this system.
www.s gm-inc .com
GLENWOOD SPRINGS 118 West Sixth St, Suite 200 | Glenwood Springs, CO 81601 | 970.945.1004
www.s gm-inc .com
GLENWOOD SPRINGS 118 West Sixth St, Suite 200 | Glenwood Springs, CO 81601 | 970.945.1004
The design and layout of the system is shown on the attached drawing following this letter.
Upon your receipt and review, if you have any questions, please don’t hesitate to call.
Respectfully,
SGM‐Inc.
Jefferey S. Simonson, PE, CFM
Principal
www.s gm-inc .com
GLENWOOD SPRINGS 118 West Sixth St, Suite 200 | Glenwood Springs, CO 81601 | 970.945.1004
7/23/20
Client:Lee OWTS Project Location:CR 202
0789 CR 202 High Lonesome Ranch
Debeque, Colorado Debeque, CO
Date: 20‐Jul‐20
Flow Data for the OWTS Design
1 Home Use (4 Bedroom Home) 525
Total= 525
Home Use 525 gpd 0.48 #/day
Totals: 525 gpd 0.48 #/day
Soil Data for the OWTS
2 Data from on‐site soil observations: Appears to be a silty clay loam soil of consistent
depth from surface beyond a depth of 8 feet where the depth of the profile pit was excavated.
At a depth of 8', neither bedrock or groundwater have been encountered.
Data from the web soil survey indicates an Panitchen Loam exists.
From tactile soil evaluation and NRCS Websoil data, the silty clay loam is present
Given the consideration of all data, the Long Term Acceptance Rate to use is 0.275 gallons/sf/day
OWTS Design Report and Calculations
For Home Use, 2 persons per bedroom and 75 gallons per day per person, BOD5 = 0.06
#/person/day for up to 3 bedrooms and 1 person per bedroom there after
Septic Tank Sizing
3 Flow calculated from above: 525 gpd
48 hour detention time for septic tank sizing; Volume= 1050 gpd
Install a 1250 gallon tank. (Records reflect 1250 gallon tank in use)
Sizing of Absorption Field or Soil Treatment Area
5 Going with average of a soil type 3and 4 and Treatment Level 1, LTAR = 0.275 g/sf/d
For a pressure dosed system, size adjustment factor is 1.0 for a bed configuration
For a gravity system, the size adjustment factor shall be 1.2 for a bed configuration
For a gravity trench system, adjustment factor = 1.0
For a pressure dosed trench system, adjustment factor = 0.8
For use of chambers: size adustment factor is 0.7
STA= Flow/LTAR 1909 square feet (unfactored)
For a chamber system, gravity flow, adjust size to 0.7*1909= 1336 square feet
For a chamber system in a trench configuration, length=445 feet
(this would equate to 5 runs of 89.1 feet each)
With the effective length of a Quick4 chamber at 4', use 23 chambers per trench for five trenches
(total length of each trench is thus 92 feet long)
Figure 1‐ Profile Hole #1
Figure 1A‐ Profile Hole #1 Close Up
Figure 2‐ Profile Hole #2
Soil Testing for
Lee OWTS
0789 CR 202, Debeque, Colorado
Photo Documentation
Date: 7/13/2020
Figure 1B‐ Profile Hole #1‐Second Close Up
Figure 2A‐ Profile Hole #2‐Close Up Figure 2B‐ Profile Hole #2‐Second Close Up
Figure 3‐ Existing Soil Treatment Area Figure 4‐ Existing Soil Treatment Area #2
Figure 5‐ Existing Septic Location with Soil Treatment
Area in Backgroound
Graphic Scale
In Feet: 1" = 20'
0 10 20 40
Job No.
Drawn by:
Date:
Of
File:
PE:QC:
Revision#Date By
2020-356.001
KS
7/20/20
JSS
Lee OWTS-BM
RB
1
1
Garfield County, Colorado
Lee Residence
0789 CR 202, Debeque, CO
OWTS Design and DetailsSchematic for Permit
and Construction 118 West Sixth Street, Suite 200
Glenwood Springs, CO 81601
970.945.1004 www.sgm-inc.com
QUICK4 STANDARD MULTIPORT END CAP
INFILTRATOR SYSTEMS INC.
QUICK4 STANDARD CHAMBER
INSPECTION PORT
48"
(EFFECTIVE)
52"
34"
12"