HomeMy WebLinkAboutApplication- Permit)'GARFIELD COUNTY BUILDING AND SANITATION DEPARTMENT
109 8th Street Suite 303
Glenwood Springs, Colorado 81601
Phone (303) 945-8212
INDIVIDUAL SEWAGE DISPOSAL PERMIT
j PROPERTY �J
Owner's Name ar4C I f.0 COCA'f�
System Location
Permit W.. 36 1 1
Assessor's Parcel No.
This does not constitute
a building or use permit.
Present Address iu t `" 9 . G • S 81101 Phone 9 5 y
`11'10-tAfi4e OR -
60511
,(Llegal Description of Assessor's Parcel No. ..
Y o 't). V' 1:4 (3GF'L,.-�i41�`( ('�/)Li .I ,
IIV
y
t SYSTEM DESIGN
Septic Tank Capacity (gallon) Other
Percolation Rate (minutes/inch) Number of Bedrooms (or other)
CCCi
Required Absorption Area - See Attached x-71-^ C.
Special Setback Requirements: ��'1fff��_ 1r.
Date Inspector
FINAL SYSTEM INSPECTION AND APPROVAL (as installed)
Call for Inspection (24 hours notice) Before Covering Installation
System Installer
Septic Tank Capacity
Septic Tank Manufacturer or Trade Name
Septic Tank Access within 8" of surface
Absorption Area
Absorption Area Type and/or Manufacturer or Trade Name
Adequate compliance with County and State regulations/requirements
Other
Date Inspector
IZ-ui 4414-'1? P _ k 'TFCC ttred)
RETAIN WITH RECEIPT RECORDS AT CONSTRUCTION SITE
*CONDITIONS:
1. All installation must comply with all requirements of the Colorado State Board of Health Individual Sewage Disposal Systems Chapter
25, Article 10 C.R.S. 1973, Revised 1984.
2. This permit is valid only for connection to structures which have fully complied with County zoning and building requirements. Con-
nection to or use with any dwelling or structures not approved by the Building and Zoning office shall automatically be a violation or a
requirement of the permit and cause for both legal action and revocation of the permit.
3. Any person who constructs.alters, or installs an individual sewage disposal system in a manner which involves a knowing and material
variation from the terms or specifications contained in the application of permit commits a Class 1, Petty Offense ($500.00 fine —6
months in jail or both).
White - APPLICANT Yellow - DEPARTMENT
INDIVIDUAL SEWAGE DISPOSAL SYSTEM APPLICATION
OWNER 4iNecteLD C.vu►JT'( 2D&D 4 E 1 gig_ Dept-
ADDRESS
ei'T
ADDRESS `102 TA U(iHEra >3ALi 6, l.f BLVD (21 eta PHONE 62 - t.)(0 oI
CONTRACTOR _.313-S COP -1ST -20 GTl p, -..I
ADDRESS 6127 Zb 2D/ GQ t t -I D �U r�1CT1 0►J
PERMIT REQUEST FOR (X) NEW INSTALLATION
PHONE 91D- 2L11 --(..i/
( ). ALTERATION ( ) REPAIR
Attach separate sheets or report showing entire area with respect to surrounding areas, topography of area, habitable
building, location of potable water wells, soil percolation test holes, soil profiles in test holes (See page 4).
LOCATION OF PROPOSED FACILITY: 1
Near what City of Town C LES k1 ocOG s PteJ ell)$.t S Size of Lot 5 AC Q iS
Legal Description or Address 25I2v ti ln1'( S2- C VAP S C O Y,I boi
WASTES TYPE:
( ) DWELLING ( ) TRANSIENT USE
(0 COMMERCIAL OR INDUSTRIAL ( ) NON-DOMESTIC WASTES
( ) OTHER - DESCRIBE
BUILDING OR SERVICE TYPE: \(t&tr f t,-rov i\ -la fi
Number of Bedrooms
( ) Garbage Grinder
r>FFs c e -
( ) Automatic Washer
Number of Persons 1 0
( ) Dishwasher
SOURCE AND TYPE OF WATER SUPPLY: 4C) WELL ( ) SPRING ( ) STREAM OR CREEK
If supplied by Community Water, give name of supplier:
DISTANCE TO NEAREST COMMUNITY SEWER SYSTEM: (0 MILE. AQP Rok • R . F, W. S. P.
Was an effort made to connect to the Community System? II O t COST p ¢pl.I (EATS
A site elan is required to be submitted that indicates the following MINIMUM distances:
Leach Field to Well: 100 feet
Septic Tank to Well: 50 feet
Leach Field to Irrigation Ditches, Stream or Water Course: 50 feet
Septic System to Property Lines: (septic tank &leach field)10 feet
YOUR INDIVIDUAL SEWAGE DISPOSAL SYSTEM PERMIT WILL NOT BE ISSUED WITHOUT
A SITE PLAN.
GROUND CONDITIONS:
Depth to first Ground Water Table to -f# Fee_ WELL D e l u -ER S Wei
Percent Ground Slope H (10 GeD.PE Gitarc `-L-K
2
TYPE OF INDIVIDU y+L SEWAGE DISPOSAL SYSTEM PROPOSED:
(r ) SEPTIC TANK ( ) AERATION PLANT ( ) VAULT
( ) VAULT PRIVY ( ) COMPOSTING TOILET ( ) RECYCLING, POTABLE USE
( ) NT PRIVY ( ) INCINERATION TOILET ( ) RECYCLING, OTHER USE
( ) CHEMICAL TOILET (X OTHER - DESCRIBE G Y AJ E11.E S':> A'Spp Ti o rJ 712E tJC-}(
FINAL DISPOSAL BY:
(X) ABSORPTION TRENCH, BED OR PIT ( ) EVAPOTRANSPIRATION
( ) UNDERGROUND DISPERSAL ( ) SAND FILTER
( ) ABOVE GROUND DISPERSAL ( ) WASTEWATER POND
( ) OTHER - DESCRIBE
WILL EFFLUENT BE DISCHARGED DIRECTLY INTO WATERS OF THE STATE? f -J 0
PERCOLATION TEST RESULTS: (To be completed by Registered Professional Engineer, if the Engineer does the
Percolation Test)
Minutes twit= % per inch in hole No. 1 Minutes per inch in hole NO. 3
Minutes 210. 7 per inch in hole No. 2 Minutes per inch in hole NO. _
Name, address and telephone of RPE who made soil absorption tests: Do 12-P1 to -k so N 312 -
HP 4F.c., iEc4-1 . 4 W 5 CD , gJlb°!
Name, address and telephone of RPE responsible for design of the system: PAW- L' u FL E D`i'
51/p12k`� Erxt ^�6s�cN — 012o- 1 c>% -I - 0 11 cKRgo.-abAa-6 CO .
Applicant acknowledges that the completeness of the application is conditional upon such further mandatory and
additional tests and reports as may be required by the local health department to be made and furnished by the applicant
or by the local health department for purposed of the evaluation of the application; and the issuance of the permit is
subject to such terms and conditions as deemed necessary to insure compliance with rules and regulations made,
information and reports submitted herewith and required to be submitted by the applicant are or will be represented to
be true and correct to the best of my knowledge and belief and are designed to be relied on by the local department of
health in evaluating the same for purposes of issuing the permit applied for herein. I further understand that any
falsification or misrepresentation may result in the denial of the application or revocation of any permit granted based
upon said application and in legal action for perjury as provided by law.
Signed
,f)cy
Date � ((- Zvi' Z
PLEASE DRAW AN ACCURATE MAP TO YOUR PROPERTY!!
3
MA'Y-17-2002 09:35
P.01
a
May 16, 2002
Jeff T. Nelson
Assistant County Engineer
Garfield County Engineering Department
109 8th Street, Suite 100C
Glenwood Springs, CD 81601
Post -le Fax Note 7871
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RE: As -Built ISDS - Garfield County,t&The txtea t nbp, 4arneta eo t.1
SE Job No. 21094.01
Dear Jeff:
Pursuant to County Regulations, this letter provides documentation that the new ISDS system recently installed is in
general compliance with the permitted design. Sopris Engineering has performed site visits to measure, inspect,
and document the u built conditions of the constructed system. We have coordinated our efforts with the
contractor that built the system. The various components of the system were inspected prior to bacic"illing and after
all installations were completed. The as -built conditions and installation of the new 1SDS components is in
compliance with the design specifications for the system. Inspections of the soil conditions within the absorption
field area confirmed suitable conditions for the system design therefore the specified number of leaching chambers
were installed over 6"•12" of filter sand. The as -built location of the new ISDS system is within the general
orientation and location as delineated on the record drawing dated 12/5/01.
A 1000 gallon dual compartment septic tank was Installed with 4" tee baffles and an effluent filter. Inspection ports
were installed on the ends of the trenches. The absorption field was constructed as delineated on the site plan. The
two 3' x44' trenches were installed level utilizing specified materials installed according to design. The minimum
setback distances have been maintained.
The septic tank. distribution pipe, and installation are in accordance with Garfield County Regulations, the design
presented in the Sopris Engineering Report, dated September 17, 2001 and the design drawing, dated December 5,
2001.
If you have any questions or need any additional information, please call.
502 Main Street • Suite A3 • Carbondale, CO 81623 • (970) 704-0311 • Fax (970) 704-0313
SoPRIS ENGINEERING • LLC
civil consultants
TOTAL P.01
GecPtech
August 23, 2001
Garfield County Road and Bridge
Attn: Jeff Nelson
109 8th Street, Suite 300
Glenwood Springs, Colorado 81601
Hepworth-Pawlak Geotechnical, Inc.
5020 County Road 154
Glenwood Springs, Colorado 81601
Phone: 970-945-7988
Fax: 970-945-8454
hpgeo@hpgeotech.com
Job No. 101 570
Subject: Subsurface Study for Foundation Design, Proposed Shop Building, Next
to M & M Construction, Highway 82, Garfield County, Colorado.
Dear Mr. Nelson:
As requested, Hepworth-Pawlak Geotechnical, Inc. performed a subsurface study for
design of foundations at the subject site. The study was conducted in accordance with
our agreement for geotechnical engineering services to Garfield County Road and
Bridge dated August 8, 2001. The data obtained and our recommendations based on the
proposed construction and subsurface conditions encountered are presented in this
report.
Proposed Construction: The proposed 100' x 150' shop building will be a tall single
story steel frame structure with metal siding located on the site as shown on Fig. 1.
Ground floor will be slab -on -grade. Cut depths are expected to be between about 4 to 6
feet. Foundation loadings for this type of construction are assumed to be relatively light
and typical of the proposed type of construction.
If building conditions or foundation loadings are significantly different from those
described above, we should be notified to re-evaluate the recommendations presented in
this report.
Site Conditions: The site is located in an existing Garfield County gravel pit. The ►:
ground surface in the proposed building area slopes gently down to the west. There is ELI
about 8 to 10 feet of elevation difference across the proposed building area. Steep cuts „
GI tri
from operation of the gravel pit are located to the north and east of the proposed Q6 ,,,-
building. There is no vegetation in the building area. Vegetation on the steep slope toM°D
the east consists of sagebrush, grass and weeds. There were parked construction pc '/'
equipment and stored culverts located along the west property line.
Subsurface Conditions: The subsurface conditions at the site were evaluated by
excavating three exploratory pits at the approximate locations shown on Fig. 1. The
logs of the pits are presented on Fig. 2. The subsoils encountered in the pits generally
consist of medium dense to dense, slightly silty, sandy gravel with cobbles and small
boulders. Weathered siltstone bedrock of the Eagle Valley Evaporite was encountered
Garfield County Road & Bridge
August 23, 2001
Page 2
in Pit 2. About 11/2 feet of on-site granular fill was exposed above the natural gravels in
Pit 3. Results of consolidation testing performed on a relatively undisturbed sample of
the weathered siltstone bedrock, presented on Fig. 3, indicate low compressibility under
conditions of loading and wetting. No free water was observed in the pits at the time of
excavation and the soils and bedrock materials were slightly moist.
Foundation Recommendations: Considering the subsurface conditions encountered in
the exploratory pits and the nature of the proposed construction, we recommend spread
footings placed on the undisturbed natural gravels or bedrock materials designed for an
allowable bearing pressure of 4,000 psf for support of the proposed building.
Differential settlement could occur between footings bearing on the gravels and footings
bearing on the bedrock especially if the bearing materials were to become wetted.
Footings should be a minimum width of 16 inches for continuous walls and 2 feet for
columns. Loose disturbed soils and rock and existing fill encountered at the foundation
bearing level within the excavation should be removed and the footing bearing level
extended down to the undisturbed natural gravels or bedrock. Voids created by the
removal of large rock should be backfilled with compacted sand and gravel or with
concrete. Exterior footings should be provided with adequate cover above their bearing
elevations for frost protection. Placement of footings at least 36 inches below the
exterior grade is typically used in this area. Continuous foundation walls should be
reinforced top and bottom to span local anomalies such as by assuming an unsupported
length of at least 10 feet. Foundation walls acting as retaining structures (if any) should
be designed to resist a lateral earth pressure based on an equivalent fluid unit weight of
at least 45 pcf for the on-site gravels, excluding oversized rock, as backfill.
Floor Slabs: The natural on-site soils and bedrock materials are suitable to support
lightly to moderately loaded slab -on -grade construction. To reduce the effects of some
differential movement, floor slabs should be separated from all bearing walls and
columns with expansion joints which allow unrestrained vertical movement. Floor slab
control joints should be used to reduce damage due to shrinkage cracking. The
requirements for joint spacing and slab reinforcement should be established by the
designer based on experience and the intended slab use. A minimum 4 inch layer of
free -draining gravel should be placed beneath slabs -on -grade as a leveling course and to
facilitate drainage. This material should consist of minus 2 inch aggregate with less
than 50% passing the No. 4 sieve and less than 2% passing the No. 200 sieve.
All fill materials for support of floor slabs should be compacted to at least 95 % of
maximum standard Proctor density at a moisture content near optimum. Required fill
can consist of the on-site gravel soils devoid of vegetation, topsoil and oversized rock.
Surface Drainage: The following drainage precautions should be observed during
construction and maintained at all times after the building has been completed:
Garfield County Road & Bridge
August 23, 2001
Page 3
1) Inundation of the foundation excavations and underslab areas should be
avoided during construction.
2) Exterior backfill should be adjusted to near optimum moisture and
compacted to at least 95% of the maximum standard Proctor density in
pavement and slab areas and to at least 90% of the maximum standard
Proctor density in landscape areas.
3) The ground surface surrounding the exterior of the building should be
sloped to drain away from the foundation in all directions. We
recommend a minimum slope of 6 inches in the first 10 feet in unpaved
areas and a minimum slope of 3 inches in the first 10 feet in pavement
and walkway areas. A swale will be needed on the east and north sides
of the building to direct surface runoff around the building.
4) Roof downspouts and drains should discharge well beyond the limits of
all backfill.
5) We understand that drywells are proposed for disposal of surface runoff
from the shop roof and wash pad. It is possible that shallow bedrock
may be encountered in the drywell excavations. While the natural
gravels at the site are suitable for drywells and probably have relatively
rapid percolation rates, the siltstone bedrock is not suitable for drywell
disposal. The drywells should be located as far as practical from
buildings and other structures. An overflow pipe should be provided or
if they area catch basin type structures, a valley pan or grade swale
should be provided to route overflow away from structures at the site.
Limitations: This study has been conducted in accordance with generally accepted
geotechnical engineering principles and practices in this area at this time. We make no
warranty either expressed or implied. The conclusions and recommendations submitted
in this report are based upon the data obtained from the exploratory pits excavated at the
locations indicated on Fig. 1 and to the depths shown on Fig. 2, the proposed type of
construction, and our experience in the area. Our findings include interpolation and
extrapolation of the subsurface conditions identified at the exploratory pits and
variations in the subsurface conditions may not become evident until excavation is
performed. If conditions encountered during construction appear different from those
described in this report, we should be notified at once so re-evaluation of the
recommendations may be made.
This report has been prepared for the exclusive use by our client for design purposes.
We are not responsible for technical interpretations by others of our information. As
the project evolves, we should provide continued consultation and field services during
construction to review and monitor the implementation of our recommendations, and to
verify that the recommendations have been appropriately interpreted. Significant design
changes may require additional analysis or modifications to the recommendations
presented herein. We recommend on-site observation of excavations and foundation
H -P GEOTECH
Garfield County Road & Bridge
August 23, 2001
Page 4
bearing strata and testing of structural fill by a representative of the geotechnical
engineer.
If you have any questions or if we may be of further -assistance, please let us know.
Sincerely,
HEPWORTH - PAWLAK 'at� H i w %. INC.
_ OZ I
Jordy Z. Adamso�i, Jr/, j 9i
�T.5.A7 ul 43.
�,' S
NAL EN!
Reviewed by:
Daniel E. Hardin, P.E.
JZA/ksw
attachments
cc: Enartech - Attn: Chuck Peterson
LI n n
• 6100
6090
6080
6070 I
6060
r
I1
1
1
I
/
- 6100
••••• - - 6090
/ PIT 1 -_ SlGb�OMn
6080
6070
/
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/-1 ilL
/ Atv.
/ ocik
PROPERTY
BOUNDARY
BENCH MARK: GROUND SURFACE ELEVATION
6056' ASSUMED BASED ON TOPOGRAPHY SHOWN
ON SITE PLAN PROVIDED.
6060
NOTE: TOPOGRAPHY IN
BUILDING AREA IS
APPROXIMATE DUE
TO RECENT SITE
GRADING.
APPROXIMATE SCALE
11' 60'
101 570
HEPWORTH—PAWLAK
GEOTECHNICAL, INC.
LOCATION OF EXPLORATORY PITS
Fig. 1
.o
o.
0
0
5
— 10
LEGEND:
PIT 1
ELEV.= 6074'
PIT 2 PIT 3
ELEV.= 6072' ELEV.= 6068'
Wf-8.8
00=025
0 _
5
10
FILL; silty sandy gravel with cobbles and small boulders, medium dense, slightly moist, brown.
GRAVEL (GM—GP); sandy, slightly silty, more sandy in Pit 3, with cobbles and small boulders,
medium dense to dense, slightly moist, brown, rounded rock.
WEATHERED SILTSTONE BEDROCK; medium hard, slightly moist, brown, light gray to
grayish green. Eagle Valley Evaporite.
2' Diameter hand driven liner sample.
Refusal to digging with backhoe.
NOTES:
1. Exploratory pits were excavated on August 13, 2001 with a JD -310D backhoe.
2. Locations of exploratory pita were measured approximately by pacing from features on the site plan
provided.
3. Elevations of the exploratory pits were obtained by Interpolation between contours on the site plan
provided and checked by hand level referring to the assumed Bench Mark shown on Fig. 1. Logs are
drawn to depth.
4. The exploratory pit locations and elevations should be considered accurate only to the degree implied
by the method used.
5. The lines between materials shown on the exploratory pit logs represent the approximate boundaries
between material types and transitions may be gradual.
6. No free water was encountered In the pits at the time of excavating. Fluctuations in water level may
occur with time.
7. Laboratory Testing Results:
WC = Water Content ( X )
DD = Dry Density ( pcf )
Depth — Feet
101 570
HEPWORTH—PAWLAK
GEOTECHNICAL, INC.
LOGS OF EXPLORATORY PITS
Fig. 2
K 0
g1
C
n.
J2
•
•
Moisture Content •• 8.8 percent
Dry Density - 125 pcf
Sample of: Weathered Siltetone
From: Pit 2 at 3.5 Feet
•
•
No movement
upon
wetting
•
0.1 1.0 0 100
APPLIED PRESSURE — ksf
101 570
HEPWORTH-PAWLAK
GEOTECHNICAL, INC.
SWELL CONSOLIDATION TEST RESULTS
Fig. 3
To:
Project:
Date:
Garfield County Engineering Department
Transmittal
Tom Russell, Paul Rutledge, and Chuck Brenner
cattle creek road n bridge shop
Tuesday, August 28, 2001
METHOD OF DELIVERY:
US MAIL
U.P.S.
FED EX
FAX 625-8627,
704-0313, 1'
-
O.S.M.
IN PERSON
OTHER
11
ITEM NO.
QUANTITY
DESCRIPTION
1
7 pages
Subsurface study for foundation design by HP Geotech
DATE OF
DOCUMENT
8-23-2001
COMMENTS:
Sincerely,
Jeff T Nelson
Assistant County Engineer
T D3
Page 1 of 1
109 8th Street, suite 100-c, Glenwood Springs, CO. 81601-3360, Telephone 945-1377 ext. 4013
Www Garfield-countv corn Email Jnelsonraaarfield-countv corn
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•
Gettecr,
October 4, 2001
Garfield County Road and Bridge
Attn: Jeff Nelson
109 8th Street, Suite 300
Glenwood Springs, Colorado 81601
Hepworth-Pawlak Geotechnical, Inc.
5020 County Road 154
Glenwood Springs, Colorado 81601
Phone: 970-945-7988
Fax: 970-945-8454
hpgeo@hpgeotech.com
Job No. 101 570
Subject: Percolation Testing for Proposed Drywells, Proposed Shop Building,
Next to M & M Construction, Highway 82, Garfield County, Colorado.
Dear Mr. Nelson:
As requested by Paul Rutledge with Sopris Engineering, Hepworth - Pawlak
Geotechnical, Inc., performed percolation testing for proposed drywells at the subject
site. The drywells are proposed for disposal of water from the wash pad, roof drains
and surface runoff. We previously conducted a subsurface study for the proposed shop
building and presented our findings in a report dated August 23, 2001, Job No. 101
570.
Two drywells are proposed in the areas of the percolation test pits shown on Fig. 1.
The pits had been excavated prior to our field work. We understand that about 500
gallons of water had been placed in each of the pits on September 16, 2001. At the
time of our testing the water placed the previous day had drained from Test Pit 1 and
about 1 foot of water remained in Test Pit 2. A test hole (nominal 12 inch diameter by
12 inch deep) was hand dug in the bottom of Test Pit 1 for testing. The subsoils
exposed in the pits consist of slightly silty sandy gravel with cobbles and boulders to the
pit depths of about 7 and 9% feet.
Percolation testing was conducted on September 17, 2000. The percolation test results
are summarized on Table I. A percolation rate between about 2 and 10 minutes per
inch under a relatively low water head was indicated from the test in Test Pit 1. The
water from the previous day soaking remained in Test Pit 2. We expect the percolation
rate in Test Pit 1 would be higher under full head from the wash pad or a design storm
runoff. Additional subsurface study would be needed in the area of Test Pit 2 to
determine if bedrock could be the cause for the ponded water. The granular soils
exposed in Test Pit 2 are similar to those exposed in Test Pit 1 and should have a
similar infiltration rate.
RECEIVED
OCT 05 2031
GARFIEt_D COUN-ry
Garfield County Road and Bridge
October 4, 2001
Page 2
A minimum size dry well of 5 feet diameter by 5 feet perforated length and 8 feet total
length is recommended. The actual capacity of the wells could be determined after
construction. The site should be graded to drain in the event the drywell capacity is
exceeded. An open graded drain gravel (such as 3/4 inch to 11/2 inch screened rock)
having a maximum size of 2 inches and less than 2% passing the No. 200 sieve should
be used as backfill inside and outside of the perforated section. The on-site granular
soils, excluding rock greater than about 8 inches in size, can be used as backfill around
the non -perforated sections. Underground inlet pipes should be placed below frost
depth.
If you have any questions or need further assistance, please call our office.
Sincerely,
HEPWORTH - PAWLAK G
►;s. .p. k":�_ INC.
• f:
i4
Jordy Z. Adamson
Rev. By: DEH
JZA/ksw
attachments
cc: Enartech - Attn: Chuck Peterson
Sopris Engineering - Attn: Paul Rutledge
' 6100
6100
6090
6080
6070
6080
TEST PIT P-2, 3.-
.-- /
�� l
1 \.-- ti
S.C1
PROPERTY
BOUNDARY
BENCH MARK: GROUND SURFACE ELEVATION =
6056' ASSUMED BASED ON TOPOGRAPHY SHOWN
ON SITE PLAN PROVIDED.
6060
LEGEND
❑ PERCOLATION TEST PIT
II PIT EXCAVATED FOR
PREVIOUS STUDY
NOTE: TOPOGRAPHY IN
BUILDING AREA IS
APPROXIMATE DUE
TO RECENT SITE
GRADING.
APPROXIMATE SCALE
1" - 60'
C 7
101 570
HEPWORTH-PAWLAK
GEOTECHNICAL, INC.
LOCATION OF EXPLORATORY PITS
Fig. 1
HEPWORTH-PAWLAK GEOTECHNICAL, INC.
TABLE I
PERCOLATION TEST RESULTS
JOB NO. 101 570
HOLE NO.
HOLE DEPTH
(INCHES)
LENGTH OF
INTERVAL
(MIN)
WATER DEPTH
AT START OF
INTERVAL
(INCHES)
WATER DEPTH
AT END OF
INTERVAL
(INCHES)
DROP IN
WATER
LEVEL
(INCHES)
AVERAGE
PERCOLATION
RATE
(MIN./INCH)
P-1
84
6
water added
water added
9 3/4
8
1 3/4
2.9
2.0
6.7
6.7
10.0
10.0
5.0
2.9
10.0
10.0
11 1/2
9
2 1/2
9
8 1/4
3/4
8 1/4
7 1/2
3/4
7 1/2
7
1/2
7
6 1/2
1/2
10 1/2
9 1/2
1
9 1/2
7 3/4
1 3/4
7 3/4
7 1/4
1/2
7 1/4
6 3/4
1/2
P-2
115
20
12
12
0
did not perc
did not perc
26.7
12
12
0
12
11 1/4
3/4
Note: A percolation test hole was dug in the bottom of test pit P-1. Test pit P-2 had about 1
foot of water from the previous day soaking.
September 17, 2001
Jeff T. Nelson
Assistant County Engineer
Garfield County Engineering Department
109 8th Street, Suite 100C
Glenwood Springs, CO 81601
RE: Drainage Report and ISDS design for the Proposed Garfield County, Cattle Creek Shop.
SE Job No. 21094.01
Dear Jeff:
Pursuant to your request, attached herewith is a letter/report presenting our findings in regard to site
grading, drainage and design of an Individual Sewage Disposal System (ISDS) for the above referenced
Site. Our drainage design is in accordance with Garfield County Design and Construction Standards.
Our ISDS recommendations are in accordance with Garfield County and the State of Colorado ISDS
Regulations. We have reviewed the information forwarded to us which includes the site plan, architectural
drawings, Geotechnical Report and conducted a site visit, formulated a drainage design, an ISDS design
and created a site plan with construction details as part of our scope of work.
Conclusions:
Based on our findings we believe that the design and installation of an approved drainage system is feasible
in accordance with the Regulations of Garfield County. We recommend that two underground stormwater
retention and infiltration facilities be installed to attenuate stormwater flows from the developed County
shop project. The difference in the pre and post development runoff volume is retained on site and is
retained and recovered by percolation into the ground. Our design is outlined below and delineated on the
attached site plan.
Based on our findings we believe that the design and installation of an approved ISDS system is feasible in
accordance with the Regulations of Garfield County and the State of Colorado. We recommend that a
new 1000 gallon septic tank be installed that will discharge effluent to a 210 square foot soil absorption
trench system. The soil absorption system can be installed in natural soils. The system will meet all
required setbacks and be installed within the general boundaries indicated on the plan. Our Design is
outlined below and delineated on the attached site plan.
Site Location:
The subject site is located on the east side of State Highway 82 Frontage Road in Garfield County,
Southeast of the intersection of County Road 113 and Highway 82. The site is situated in Section, 7 T 7 S,
R 88 W of the 6th P.M. The area to be redeveloped on the Site comprises approximately 2.2 acres. The
site is bounded on the west by Highway 82, on the east and south by steep undeveloped hillside and on the
north by a driveway adjacent to existing commercial properties.
502 Main Street • Suite A3 • Carbondale, CO 81623 • (970) 704-0311 • Fax (970) 704-0313
Sorais ENGINEERING • LLC civil consultants
Jeff Nelson
SE Job No. 21094.01
September 17, 2001
Page 2
Existing Site Conditions:
The site is located in an existing Garfield County gravel pit. The approximately 2.2 acre site lies outside of
the 100 -year -flood plain. The existing grade on site is moderate with a slight slope to the north and west.
Steep slopes characterize the perimeter of the site to the east and south. An established defined drainage
system does not currently exist. The area to be developed has a maximum relief of approximately 10 feet.
A berm exists along the western boundary of the site, which adjoins the Highway right-of-way. The area to
be developed is not vegetated. The steep slopes have sparse vegetation including sagebrush, grasses, shrubs
and weeds. The pre -development drainage flow path on the site generally runs toward the northwest
toward the frontage road.
Proposed Site Conditions:
A new road and bridge shop facility is proposed on the Garfield County Property. The project includes the
development of up to 12,000 S.F. of building area. The building will be used for vehicle and equipment storage.
The building will include 2000 S.F. of office and storage space with two bathrooms. A mobile fueling facility along
with storage and staging facilities for road and bridge materials will be located on the site. A 20' x 60' wash bay
will be constructed adjacent to the shop building. The proposed improvements will include gravel parking
areas, driveways, ISDS facilities and undisturbed/landscape areas. Water will be supplied by a newly
registered well, on the property.
Our primary drainage consideration involves the collection, detention and infiltration of storm water runoff
from approximately 2.2 acres of the proposed site development. The Post development impervious runoff
surface area will comprise approximately 13 % of the design drainage basin. Storm water runoff will be
collected and routed to storm water retention facilities during large events and drain in underground
infiltration areas via drainage swales and roof drainage pipes. In general the proposed site grading conveys
storm water into two sub -basins. Sub -Basin 1 handles the runoff from the roof, and a smaller portion of
the unpaved site. Sub -Basin 2 handles the runoff from the interior driveway/storage/staging areas and the
majority of the unpaved site.
Subsurface Conditions:
A subsurface investigation was conducted on August 13, 2001 by Hepworth-Pawlak Geotechnical, Inc. The
report is dated August 23, 2001, Job Number 100 570. The soils on site are consistent with alluvial and
colluvial material typically found in a gravel pit area. The subsoil encountered at the site consists of
slightly silty, sandy gravel with cobbles and small boulders. Weathered siltstone bedrock was encountered
in one of the profile pits. No groundwater was encountered in an exploration pits to a depth of 4 feet.
Based on our knowledge and observations in the area, we assume that seasonal high ground water levels
will be at least 20 feet below the existing surface. For this design we are assuming that the seasonal high
groundwater level will be below the proposed stormwater retention/infiltration and ISDS facilities and
present no adverse effects. If ground water and/or bedrock are encountered during excavation we
recommend that the conditions be evaluated in regard to the proposed design. Percolation tests have not
been conducted however tests are to be preformed in the final staked out locations of the drywells and
ISDS absorption field.
Jeff Nelson
SE Job No. 21094.01
September 17, 2001
Page 3
Drainage Design:
The drainage design is based on the Rational Method used for the hydrologic analysis. This method was
chosen due to the small drainage areas and the required retention to be provided. Garfield County requires
the design to be based on the 25 -year design storm.
Drainage Design Criteria:
The volumetric difference between the pre and post development runoff will be retained and infiltrated into
the ground. The calculated runoff from the design storm events is determined by utilizing the maximum
rain fall intensity on the time -intensity -frequency curve. The post development runoff offsite will not
exceed the pre development runoff on site. Our design is very conservative for the purpose of handling
larger infrequent storm events and to increase the longevity of the proposed systems.
The proposed development area is approximately 2.2 acres divided into 3 sub -basins of which Sub -Basin 1
comprising 0.52 acres will manage stormwater from the roof, surface water around the north and east sides
of the building and drainage from the wash bay. The surface water will be routed to the drywell via a
drainage swale and the roof drains and washbasin water will be routed directly to the drywell via drainage
pipes. Sub -basin 2 comprising 1.4 acres will manage storm water from the majority of the site from the
unpaved surface areas. The stormwater will sheet flow across the large yard area toward the berm on the
west boundary to a swale routed to another drywell. The third basin comprising 0.3 acres is located within
the northwest corner of the site near the entrance. This area will essentially have the same post
development hydrological conditions as pre development. Runoff will flow to the same pre development
discharge point in the retention areas west of the frontage road. A small swale may be installed off the
driveway entrance to collect and stage this runoff prior to discharge offsite, however the runoff will be
insignificant.
We have used a 25 year — 24 hour design storm as the basis of stormwater system. The appropriate Time -
Intensity -Frequency Curve for this area was utilized to calculate the rainfall volumes from the design
storm. The time of concentration is minimal for this small site. We have used an average time of 10
minutes. The rainfall intensities at 15 minutes and 60 minutes for return frequencies of 2, 25 and 100 years
and the calculated total inches of rainfall over the duration of the 25 -year storm are as follows:
Time
Minutes
10
2 -yr. Storm
Intensity
in/hr
2.4
25 -yr. Storm
Intensity
in/hr
3.9
•
100 -yr. Storm
Intensity
in/hr
4.6
Based on average rainfall intensities (inches / hour) for the 24 hour storm duration.
Jeff Nelson
SE Job No. 21094.01
September 17, 2001
Page 4
Drainage Sub -Basin Design:
Runoff on the site will be managed in 3 distinct drainage sub -basins of 0.52, 1.5 and 0.3 acres. The 0.3 -
acre Sub -Basin 3 will discharge runoff toward the frontage road drive to existing pre development storm
water facilities. The other 2 sub -basins will have new drywell retention/infiltration facilities. The
volumetric difference between the pre and post development runoff from sub basins 1 & 2 will be retained
and infiltrated into the ground. The following tables summarize the post -development sub -basin
characteristics. The pre -development conditions are assumed to be 100% non -compacted gravel.
Total Area (acres)
Impervious Area
Pervious Area
Sub -Basin 1
Ac %
0.5 26
0.3 60
0.2 40
Sub -Basin 2
Ac %
1.4 74
0.04 3
1.36 97
Combined Basin
Ac %
1.9 100
0.3 16
1.6 84
Existing facilities will handle the runoff from the Sub -Basins 3.
Runoff Calculation
The time of concentration is calculated to be a maximum of 10 minutes. The peak runoff is calculated
using the rational method and the rainfall intensity curve for the Glenwood Springs area.
The drainage design is based on the rational method formula Q=CIA whereas,
Q = Runoff measured in cubic feet per second (in/hr/ac)
I = Rainfall intensity in inches per hour
C = Runoff coefficient
A = Drainage basin area in acres
V= Volume of runoff (excess runoff)
Tc= Time of concentration (minutes)
. • •
Sub -Basin 1
Determine weighted runoff coefficient:
Jeff Nelson
SE Job No. 21094.01
September 17, 2001
Page 5
Determine pre/post development runoff :
Sub -Basin 1 Pre -Development
Q=CIA
Surface
Area (A)
C -Value
Product
Cweighted
I
Q (cfs)
Difference
Pavement/roof
0.0
0.95
0.0
Gravel surface
0.5
0.70
0.35
Total/Result
0.5
0.35
0.70
3.9
1.36
Sub -Basin 1 Post -Development
Pavement/roof
0.3
0.95
0.29
Gravel surface
0.2
0.80
0.16
Total/Result
0.5
0.45
0.9
3.9
1.75
Difference
Difference
0.40
Calculate the runoff volume as the area under the SCS standard triangular unit hydrograph where:
V = 1/2 Q (Tc+1.67Tc) =1/2(0.40)[10 + (1.67(10)] = 5.3cfs-min
5.3 cfs-min(60sec/min) = 320 CF
Sub -Basin 2
Determine weighted runoff coefficient:
Determine pre/post development runoff :
Sub -Basin 1 Pre -Development
Q=CIA
Surface
Area (A)
C -Value
Product
Cweighted
I
Q (cfs)
Difference
Pavement/roof
0.0
0.95
0.0
Gravel surface
1.4
0.70
0.98
Total/Result
1.4
0.98
0.70
3.9
3.8
Sub -Basin 1 Post -Development
Pavement/roof
0.04
0.95
0.04
Gravel surface
1.36
0.80
1.08
Total/Result
1.4
1.13
0.81
3.9
4.4
Difference
Difference
0.62
Calculate the runoff volume as the area under the SCS standard triangular unit hydrograph where:
V = 1/2 Q (Tc+1.67Tc) =1/2(0.62)[10 + (1.67(10)] = 8.2 cfs-min
8.2 cfs-min(60sec/min) = 496 CF
A minimum runoff volume of Approximately 320 CF will be stored in the drain pipes, void spaces within
the drywell, and gravel envelope in from Sub -Basin 1. A minimum runoff volume of Approximately 500
Jeff Nelson
SE Job No. 21094.01
September 17, 2001
Page 6
CF will be stored in the void spaces within the drywell, and gravel envelope in from Sub -Basin 2. Excess
runoff over the full duration of the storm events larger than the 25 -year will be handled due to the expected
rapid percolation rates. It is noted that the storm water runoff will immediately begin to infiltrate into the
soil as it is conveyed to the drywell structures allowing for rapid recovery. Due to these conditions the
calculated runoff volume is considered to be very conservative.
Wastewater from the wash bay facility will be treated and discharge to The Sub -Basin 1 drywell. The
maximum peak quantity generated is assumed to be 500-gal/day (67 C.F.). The water will drain to a
surface trench drain for initial settling treatment. The liquid and fines will discharge into a 1000 -gallon
sand and grease trap tank. The primary treated effluent will then discharge through an additional tank filter
unit install on the outlet tee in the secondary chamber of the sand/oil separator tank. We recommend the
installation of a Fossil Tee Tank Filter which will provide secondary treatment of the waste water. The
filter unit is designed to remove hydrocarbons and suspended fines. The final treated water will discharge
to the drywell. Therefore the total retention required for Sub -Basin 1 drywell is 320 + 67 = 387 C.F.
Dry Well Design:
The drywells are designed with regard to space available and to keep the hydraulic grade line below the
surface grades within the collection areas. Standard perforated 5' diameter manholes installed in a gravel
envelope will be utilized. Retention volumes will be created in each retention/infiltration facility by the
installation of a 5 -diameter Manhole (drywell); 6" diameter collection pipes (Sub -Basin 2), gravel
envelopes, and drain inlet structures. These dry wells will serve as the main retention/infiltration facility
that will accept storm water from the drainpipes and swales. All of the gravel surrounding the infiltration
chambers will be wrapped with filter fabric. All drainpipes and roof drainpipes will terminate in the
drywell (Sub -Basin 1). The lower portions of the drywell structures are to be filled with gravel for safety
and to provide a filter media, which can be maintained.
The following table presents a breakdown of the retention volumes provided:
QUANTITY
Sub -basin 1 Sub -basin 2
C.F. C.F.
Dry well 16' dia. gravel envelope voids 408 408
Drywell Volume w/o gravel 106 106
Total Retention Volume 514 514
S.F. S.F.
Infiltration Horizontal Bottom Area
201 201
• ..
Jeff Nelson
SE Job No. 21094.01
September 17, 2001
Page 7
General Notes:
Our design and recommendations are based upon data supplied to us by others. If subsurface or site
conditions are found to be different from those described in this report, we should be notified to evaluate
the effect it may have on the proposed drainage system. During excavation of the storm water retention
facilities, the engineer shall be notified in order to perform an evaluation of the subsurface soil conditions
at each facility location. These observations are required to confirm assumptions utilized in the design and
recommend modifications if necessary. If Garfield County requests changes or modifications to this
design, we should be contacted to evaluate the effect on the proposed drainage system.
• ••
Jeff Nelson
SE Job No. 21094.01
September 17, 2001
Page 8
ISDS Design Criteria:
The proposed structure contains 1 small office space, locker room, break room and shop area. There will
be a total of 3 toilets, 2 wash basins, 2 showers and 2 utility sinks. No kitchen, laundry or boarding
facilities are proposed. The design flow is calculated as follows:
Garfield County Shop expects their maximum number of personnel utilizing the facilities to be 10 people.
The design flow equivalent for the shop with two 3/4 baths is assumed to be similar to a factory with a
shower which is calculated at 35 gallons per day per employee. Due to the limited water supply and water
quality a reduced water usage is expected. We Assume that all fixtures will be water saving type. A 20%
reduction in theoretical average water usage is reasonable and expected.
From the State of Colorado County I. S. D. S. Regulation;
Average daily flow (Q) = # of people x gal/person/day (avg. flow)
Max. Design flow (Qd) = # of people x gal/person/day x 1.5 (peaking factor) = gal/day
Maximum number of office employees is assumed to be 10 people.
Gallons per day for the subject facilities = 35 gal/person/day
Qd = 10*35*1.5 = 525.al/day
Qdr(reduced) = 525*0.80 = 420 gal/day
Total Design Flow is 420 gal/day Use 420 gal/day
Septic Tank Design:
Per regulations
Qd = 420 gal/day
Volume (V) of tank = Design Flow * 1.25 (30 hour retention time)
V = 420 gal/day * 1.25 = 525
Use one 1000 -gallon septic tank
A 1000 -gallon tank is a prudent choice for possible future expansion. Use a double chamber tank with an
approved effluent filter. The tank must have appropriate access openings with risers and lids.
Percolation Rates:
Percolation tests have not been conducted however tests are to be preformed in the final staked out
locations of the ISDS absorption field. If ground water and/or bedrock are encountered during excavation
we recommend that the conditions be evaluated in regard to the proposed design. Modifications may be
made to the system based on the actual percolation rates. During excavation of the ISDS facilities, the
engineer shall be notified in order to perform an evaluation of the subsurface soil conditions. These
observations are required to confirm assumptions utilized in the design and recommend modifications if
necessary. The field is sized by using the standard absorption area equation. A rapid percolation rate
around 5 minutes per inch or less is expected in the gravel and cobbles soil matrix associated with a gavel
pit. Based on previous profiles we assume that the absorption field location will contain excessive gravel
and cobbles indicating a lack of suitable treatment medium. If excessive cobbles and boulders are
.
Jeff Nelson
SE Job No. 21094.01
September 17, 2001
Page 9
encountered a layer of replacement sandy soil may need to be placed up to a depth if 2 feet. Based on this
assumption we have based the design on the placement of a minimum 2 foot depth of a suitable sand layer
below the bottom of the absorption trenches. A soil absorption trench disposal system is recommended
however a conventional pipe and gravel system may be utilized per sizing by the engineer.
Soil Absorption System Design:
The absorption field is designed based on the placement of 2 feet of suitable sand material below the
bottom of proposed absorption trenches. Based on our assumption we have designed a system that will
treat the calculated quantity of effluent with a sand filter medium utilizing the Long Term Acceptance Rate
(LTAR). The system will treat the affluent with the minimum of two feet of select filter media underlain by
native soils. The treated effluent will then be absorbed into the natural soils across the bottom area and a
portion of the side wall areas of the trench excavation. Absorption Area required for treatment utilizing a
sand filter media system:
A = Absorption Area
Long Term Acceptance Rate method (LTAR)
Using imported sand media yields the minimum area:
LTAR maximum loading rate for sand filter media = 1.20 gal/S.F./day
A=Q/LTAR = 420/1.20 = 350 sq. ft.
We recommend using a gravelless absorption trench system. The State allows up to a 50% reduction in
absorption area if gravelless leaching chambers are used in suitable soils. To accommodate potential future
expansion and provide longevity to the system we recommend an allowed reduction in the treatment area
be limited to 40%. Absorption area per chamber unit is 15.5 S.F.
Therefore: 350 S.F. (0.60) = 210 S.F. / 15.5 S.F./ chamber = 13.5
We recommend using a trench system composed of 2 trenches 44 feet long and 3 foot wide, containing 7
standard absorption chamber units each.
The sand filtering material must be clean coarse sand, all passing the No. 4 sieve. The sand material shall
have an effective size between 0.25 and 0.6 min such that not more than 50% by weight of the granular
media is finer than 0.6 mm. The uniformity coefficient shall be 4.0 or less
An inspection port shall be installed from the top of the pre -molded cut out at the midpoint of the
beginning and terminal end chambers in the trench. The vertical inspection ports shall be 4" SDR 35 pipe
extending at least 24" above the surface and topped with a 180 -degree gooseneck fitting without a cap (non
glued) to insure air ventilation. This will allow for air exchange and for checking the performance of the
system.
•
t•
Jeff Nelson
SE Job No. 21094.01
September 17, 2001
Page 10
Soil conditions within the final staked out location of the absorption field will be evaluated after rough
grading on the site is completed. Percolation test and profile analysis will be performed and changes to the
absorption system may be made based on conditions encountered.
General Notes:
1) All materials and installation practices shall conform to Garfield County and the State of Colorado
Individual Sewage Disposal Regulations.
2) All sewer lines and distribution lines in the system shall be 4" Schedule 40 or SDR -35 PVC unless
specified otherwise on the plans.
3) Add a two-way clean out on the service line from the proposed Building.
4) The contractor shall ensure that the concrete septic tank and sewer lines are watertight.
5) The trench area must be protected to prevent damage from vehicular or livestock traffic and must be
crowned to divert drainage runoff away from the trenches.
6) A six-foot separation of undisturbed earth shall be maintained between trenches.
7) A distribution box shall be installed between the tank and the head of the trenches to insure equal
distribution between the trenches, provide inspection and allow for potential future expansion.
8) The absorption chambers shall be installed level in each trench, with a splash plate, placed on the
surface in the first chamber below the inlet to prevent scouring from the effluent.
9) A final cover of soil suitable for vegetation, a minimum 10" deep, shall be placed to the finished
surface grade.
10) The absorption trenches must be sodded or covered with vegetative ground cover.
Our design and recommendations are based upon data supplied to us by others. If subsurface or site
conditions are found to be different from those presented in this report, we should be notified to evaluate
the effect it may have on the proposed ISDS. If the County Environmental Health Department requests
changes or modifications to this design, we should be contacted to evaluate the effect on the ISDS.
If you have any questions or need any additional information, please call.
Sincerely,
SOPRIS ENGINEERING, LLC
Paul E. Ru
Desi
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