HomeMy WebLinkAboutOWTS Design Report 11.14.2016SSGM
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November 14, 2016
Mr. Andy Schwaller, Building Official
Garfield County Building Department
108 8th Street
Glenwood Springs, CO 81601
RE: Grimm Property
6634 CR 346 Silt, Colorado
OWTS Design
Dear Andy,
The purpose of this letter is to transmit the installation design regarding the onsite waste water
treatment system (OWTS) for the Grimm Residence located at Giomi Subdivision, Lot6A in Silt, Colorado.
The specific location of the property in question is located in Figure 1. .
Figure 1- Site Location of Grimm Property
The design of the proposed system accommodates a 3 bedroom home using an existing 1000 gallon
concrete septic tank and a soil treatment area consisting of Infiltrator Quick4 chambers installed in a
trench configuration at standard depth, parallel to the slope contours. The soil treatment area is being
GLENWOOD SPRINGS 118 West Sixth St, Suite 200 1 Glenwood Springs, CO 81601 1 970.945.1004
SSGM
www.sgm-inc.com
installed to replace and existing failed system. Field percolation testing has been performed indicating
percolation rates from 10 to 60 MPI exist in the soild at varyinh depth. With the percolation test results,
this has given us cause to us to rely on on-site soil observations coupled with data obtained from the
NRCS WebSoil Survey for this area. The classification and characterization of the on-site soils is that of
being a "sandy clay loam" soil. The exhibit attached to this letter identifies 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. These Exhibits are listed
as follows:
1. Exhibit A:
2. Exhibit B:
3. Exhibit C:
4. Exhibit D:
NRCS Soil Map & NRCS Hydrologic Soil Group
NRCS Hydrologic Soil Group
NRCS Unified Soil Classification
NRCS Septic Tank Absorption Fields
Based upon the soils testing and the researched data, the LTAR for the on-site soils is 0.425 gallons per
day per square foot. With this data, the STA (Soil Treatment Area) is 1,059 square feet. Because we will
incorporate the use of Infiltrators (chambers), we have employed the size adjustment factors and
reduced the bed size by the following:
For using chambers, a 0.7 factor is applied, thus resulting is an area of 741 sf. This results in four
infiltrator or chamber trenches of dimension 62' in length. Given the effective length of each infiltrator
is 4 feet, we recommend that each trench be provided with 16 units for a net length of 64'. A total of 64
Quick4 infiltrator units will be required. The attached calculations identify the thought process in the
design of this system.
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,
S 1 -1 c
S.Lirnon'
P
GLENWOOD SPRINGS 118 West Sixth St, Suite 200 1 Glenwood Springs, CO 81601 1 970.945.1004
OWTS Design Report and Calculations
Client: Kurt Grimm
6634 CR 346
Silt, Colorado 81652
Date: 14 -Nov -16
Flow Data for the OWTS Design
1 Home Use (3 Bedroom Home)
450
Total= 450
For Home Use, 2 persons per bedroom and 75 gallons per day per person, BOD5 = 0.06
#/person/day
Home Use
Totals:
Soil Data for the OWTS
450 gpd 0.48 #/day
450 gpd 0.48 #/day
2 Data from on-site soil observations: Appears to be a loamy soil of consistent
depth from surface to a depth of 10 feet where gravels and shale are encountered.
At a depth of 11', neither bedrock or groundwater have been encountered.
Data from the web soil survey indicates a Potts Loam exists.
Average of 3 percolation holes: 22190.0 mpi
2.2. I Aft.
Given the consideration of all data, the Long Term Acceptance Rate to use is 0.425 gallons/sf/day
Septic Tank Sizing
3 Flow calculated from above:
450 gpd
48 hour detention time for septic tank sizing;
1000 gallon tank exists.
Sizing of Absorption Field or Soil Treatment Area
Volume= 900 gpd
5 Going with a soil type 3 and Treatment Level 2, LTAR =
0.425 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 1059 square feet (unfactored)
For a chamber system, gravity flow, adjust size to 0.7*1059= 741 square feet
For a chamber system in a trench configuration, length= 247 feet
(this would equate to 4 runs of 62 feet each) (ZS .F CAYNK
441
With the effective length of a Quick4 chamber at 4', use 16 chambers per trench
Thus the net length of the runs will be 64' each.
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INFILTRATOR SYSTEMS INC.
QUICK4 STANDARD CHAMBER
INSPECTION PORT
52"
ESTABLISH VEGETATIVE COVER
QUICK4 CHAMBER
TYPICAL INSTALLATION
DETAIL
(Not to Scale)
9, TYP
RVA770N PIP& TYP
NARVE
•BACKRLL, TYP
W—&7V SOI! TTP
QUICK4 STANDARD MULTIPOF AW- TG
CRAW -LESS C1dANE�R
EXtSnNG
8' MAX BURIAL DEPTH
12" MIN., H-10 LOAD AREAS
6" MIN., NON—TRAFFIC AREAS
CR DE 6" O14. PVC
AVE SLEEVE
Preliminary
Not For
Construction
6' MIN
(10' SHOWN)
12"
3' 1 NO1E' IF OVER 48" IN DEPTH,, PROVIDE
OYFl AN AIR VENT 70 FACH !RENON IN UEU
OF OBSERVATION PORT. AIR VENT 70 MEND
Jr ABOVE AOVACENT 17NISH GRADE
4 TRENCH DETAIL
A0r 70 Slice
IS Design and Details
lob No 0000.000.000
Drown by: KS
Dole: 11/14/16
oc.
1 PE: 1SS
File: GrimmBN