HomeMy WebLinkAboutOWTS Design Report 06.30.2016[
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CCI ENGINEERING 1129 ·24-Road
Cronk Construction Inc. Grand Junction, CO 81505
Grand Junction (970) 245-0577 •Glenwood Springs/Aspen (970) 640-5029 • MontrosetDelta (970) 640-5029
Fax: (970) 257-7453 • Email: ccigj@msn.com
ONSITE WASTEWATER TREATMENT SYSTEM DESIGN
Date:
Prepared by :
Type of Design:
Client:
Property address:
Tax schedule No.:
Legal Descript.:
June 30, 2016
Thomas A. Cronk , P.E.
Cronk Construction Inc .
1129 -24-Road
Grand Junction, CO 81505
245-0577
residential
Royle Stillman
580 JB Court
Glenwood Springs, CO 81601
970-379-4027
580 JB Court, Glenwood Springs, CO 8160 l
2123-253-00-048
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1.0 Site History
The site consists of approximately 8. 72 acres of uncultivated native soil. Drainage is approximately 20%
to the west/southwest. A percolation test/soils evaluation was conducted on the property of reference on
06/28/16 by Tom A. Cronk, registered professional engineer (R.P.E.). The perc excavation trench
(excavation A) was located approximately 510' north of the south property line and approximately 200'
west of the east property line. Additional perc holes were located 40' north of the trench (excavation B)
and 50' south of the trench (excavation C).
The owners wish to construct a four bedroom residence at the site. The 06/30/ I 6 site investigation was
conducted to provide subsurface design parameters for an onsite wastewater treatment system (OWTS) to
serve the proposed residence.
Based on results from the 06/30116 site investigations, an engineered OWTS design has been prepared for
the property. A discussion of developed subsurface design parameters and the engineered OWTS design
follows. The site layout and location of the 06/28/16 perc test/soils evaluations are shown on the attached
plot plan. Results of the perc test/soils evaluations are attached for reference as Appendix A.
2.0 Development of Design Parameters
A perc excavation trench (excavation A) was extended to a depth of 120" below ground surface (BGS).
There was no evidence of ground water or high seasonal water table in the open excavation to a depth of
120" BGS. The soils evaluation indicates three distinct soil horizons underlie the site. A lithological
description follows:
depth (in.)
O" -18"
18" -48"
48" -120"
description
sand/clayey sand, red; (USDA-sandy loam, blocky, moderate structure)
light red sand/clayey sand (USDA-loamy sand, blocky, moderate structure)
minor gravel (I Omm-1 OOmm) in light red sand/clayey sand matrix (USDA-sand,
single grained)
As based on the results from the 06/30/16 site investigations (Appendix A), a design perc rate of 15
min/in. and corresponding long term acceptance rate (L TAR) of 0 .80 are chosen for overall system sizing
for an infiltrator trench absorption field designed to discharge to subsoils below the 48" depth.
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3.0 System Design
An INFILTRATOR absorption trench is proposed for discharge of septic effluent at the site. Construction
of the system will consist of excavating level trenches in the area comprising the absorption field. As
shown in the attached septic layout plan, the trenches will be oriented perpendicular to the natural slope to
minimize the depth of excavation along the trench length. Each trench excavation shall be continued to a
maximum depth of 48" BGS at the uphill side of the trench (see absorption field cross-section). After
removal of surface soils, the open excavations will be disked or scarified to promote subsurface
absorption.
Following completion of the initial push-outs, QUICK4 STANDARD INFILTRATORS will be used to
construct a septic effluent distribution system in the open excavations. The INFILTRATOR effluent
distribution system will be installed in accordance with the "Infiltrator Technical Manual", available from
Infiltrator Systems Inc ., 123 Elm Street, Suite 12, Old Saybrook, Connecticut 06475. Adjacent
INFILTRATORS shall be fastened with a minimum of four (4) 3/4" x #8 self-tapping sheet metal or bright
brass deck screws to prevent movement and separation during backfilling.
Septic effluent will be transferred from the upper trench to each of the adjacent downhill trenches through
a serial distribution network as shown in the attached construction details. The serial distribution
connections between adjacent trenches will facilitate the saturation of the uphill trench before septic
effluent is allowed to flow to each of the adjacent downhill trenches . As shown in the attached
Absorption Field Cross Section, the bottom of the STANDARD INFILTRATOR seepage trenches will be
located a maximum of 48" below ground level.
After the INFILTRATORS are installed, synthetic filter fabric ( 140-200 mesh) will be placed over the
trenches and the system will be covered with a soil cap. The soil cap will consist of 36" of native soil
backfill. The soil cap will be mounded 5% above the existing ground surface to promote surface run off
away from the absorption fields.
The installer should confinn the feasibility of gravity discharge of sewage effluent from the existing
septic tank to the absorption field by field verification of assumed design parameters. Assumed design
parameters with respect to gravity discharge include :
• distance from the sewage pipe at exit from the foundation to the absorption field -I 50' or
Jess,
• elevation of the ground surface at entry to the absorption field shall be no more than 6" above
the invert elevation of the sewage pipe at exit from the foundation line.
If field measurements do not confirm these design assumptions, gravity discharge of septic effluent from
the proposed structure cannot be assured and a lift station may be required. Please contact the design
engineer to address any design modifications necessary if these design assumptions are not upheld.
The installer must also confinn the setbacks from property lines, building envelopes , and existing
easements shown in the attached graphics are maintained. Four inch clean outs shall be provided at
maximum JOO' intervals in all effluent lines exceeding 100' in length. Vehicle traffic and parking is to be
prevented over the absorption and repair area. Provide minimum schedule 40 PVC under all traffic areas.
Additionally, effluent piping in traffic areas with less than 36" of cover shall be encased in 6" CMP or
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flow fill and covered with minimum 2" high density blue board insulation. Finally, any unknown utility
lines, easements , or other adverse conditions d isclosed during construction must maintain the required
setbacks listed on page 5 of this document.
A 1,250 gallon, two compartment , concrete septic tank will be used to provide a minimum of 48 hours
retention time for sewage generated from the proposed four bedroom home. A non-corrodible Orenco
filter (model# FTW0444-36) shall be installed at the final outlet tee of the existing septic tank or in the
effluent line between the septic tank and the absorption field to limit the size of solids and sludge passing
into the absorption field. The filter must be accessible for cleaning and replacement from the ground
surface .
As discussed above, INFILTRATOR absorption trenches are proposed to discharge septic effluent to the
underlying sub-soils. As shown in the attached graphics, the absorption trenches will consist of three (3)
trenches 3' wide x 48" deep x 60' long with fifteen ( 15) STANDARD INF/LTRA TOR (or equivalent) units
each for a total of forty five ( 45) units. The absorption field will encompass an effec ti ve area of 771.43
sq . ft .
Calculations and design parameters used to size the absorption field follow .
DESIGN CALCULATIONS
DESIGN LOADING RA TE OF 4 BEDROOMS x 150 GAL/BEDROOM-DAY = 600 GAL./DA Y
DESIGN PERCOLATION RATE = 15 MIN ./INCH
DESIGN LONG TERM ACCEPTANCE RA TE (LT AR) = 0.80 GAL./DA Y-SQ. FT.
A= _Q_ WHERE
l..TAR' '
A= ABSORPTION FIELD AREA (SQ. FT .)
Q= DESIGN FLOW (GAL./DA Y)
L TAR = LONG TERM ACCEPTANCE RA TE (GAL./DA Y-SQ . FT.)
A= 600 = 750 0 .80
ABSORPTION FIELD AREA ADJUSTMENT FACTOR FOR GRAVITY TRENCH DESIGN := 1.0
ABSORPTION FIELD AREA ADJUSTMENT FACTOR FOR USE OF CHAMBERS ... 0. 7
ADJUSTED ABSORPTION FIELD AREA= 750 X 1.0 X 0 .7 ... 525 SQ . FT.
USE 45 QUICK4 STANDARD INFILTRATORS AS 3 TRENCHES OF 15 UNITS EACH
CONFIGURED IN SERIAL DISTRIBUTION
ABSORPTION FIELD ADDITION SIZED AT 3 TRENCHES 3 FT . X 60 FT "" 540 SQ . FT.
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4.0 Site Specific Installation/Operation Requirements
The owner and system contractor shall be aware and comply with the following installation and system
operation requirements.
4.1 Installation • Setbacks. Notifications, and Inspections
• The system contractor must be approved and licensed by Garfield County for installation of
onsite wastewater treatment systems.
• All installation activities shall be conducted in accordance with current Garfield County
OWTS Regulations. If at any time during construction. subsurface site conditions are
encountered which differ from the design parameters developed in Section 2.0. construction
activities will stop and the design engineer will be contacted to address any necessary design
modifications.
• Installation procedures including grade, location, setbacks, septic tank size, and absorption
field size shall conform with the attached graphic details. Construction activities and system
components will not encroach upon existing easements or utility corridors. A minimum of 6
ft of undisturbed soil shall be maintained between individual absorption elements and the
septic tank and/or adjacent absorption elements. Minimum site specific setbacks for system
components are:
Source ~e12tic Tank Absor12tion Field Building Sewer
domestic water line 10' 25' 10'
domestic well 50' 100'
domestic water cistern 50' 100'
property I ines 10' 10'
unoccupied structure 5' 5'
occupied structure 10· 20'
irrigation ditch
open 50' 50'
intermittent irrigation 10' 25'
gated 10' 25'
solid pipe/li ned 10' 10'
• To avoid surface flow infiltration and saturation of the new absorption system, abandonment
of irrigation in the vicinity of the disposal system is required. Diversion ditches necessary to
divert surface flows around the new absorption bed must maintain the minimum setbacks
listed above.
• All gravity flow sewer lines and effluent distribution piping shall be 4 inches in diameter and
have glued joints. All lines discharging sewage from the residence to the septic tank shall
maintain fall of between 1/8 in. and 1/4 in. per foot and shall employ sweep 90's or 2-45's at
all turns. Sewer lines from the dwelling to the septic tank and at least 6 ft from the septic
tank outlet must meet minimum standard ASTM·3034. Sewer lines under driveways shall
always meet minimum Schedule 40 PVC standards. Additionally, effluent piping in traffic
areas with less than 36" of cover shall be encased in 6" CMP or flow fill and covered with
minimum 2" high density blue board insulation .
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• A minimum of IO" of soil cover (I 8" recommended) shall be maintained over all gravity
draining ISDS components to prevent freezing of septic effluent (excepting septic tank access
ports which must be extended to the ground surface).
• The installer shall not place the Infiltrators in the open excavation until inspected and
approved by the design engineer. Additionally, the final cover shall not be placed on sewer
lines, septic tank, or the absorption area until the system has been inspected and approved by
the design engineer. The installer shall provide 48 hour notice for all required inspections.
• Four inch clean outs shall be installed at maximum I 00' intervals in all gravity flow effluent
lines exceeding I 00' in length .
• A non-corrodible Orenco filter (model# FTW0444-36) shall be installed at the final outlet tee
of the septic tank or in the effluent line between the septic tank and the absorption field to
limit the size of solids and sludge passing into the absorption field. The filter must be
accessible for cleaning and replacement from the ground surface.
• The effluent distribution system shall be constructed in accordance with the "Infiltrator
Technical Manual" available from Infiltrator Systems Inc., I 23 Elm Street, Suite 12 , Old
Saybrook, Connecticut 06475 .
• Adjacent absorption field trenches shall be connected by a serial distribution system to assure
saturation of the upgradient trench before effluent is passed to the adjacent down gradient
trench (see attached absorption field plan view and cross section details).
• The INFILTRATORS will be covered with synthetic filter fabric (140-200 mesh) and
covered with a surface cap. The surface cap shall be mounded 5% over the absorption field.
• The system contractor shall be aware of the potential for construction activities to reduce soil
permeabilities at the site through compaction, smearing, and shearing. The following
precautions and construction procedures should be employed during installation to minimize
disturbance to native soils:
1. Excavation should proceed only when the moisture content of the soil is below
the plastic limit. If a sample of soil forms a rope instead of crumbling when
rolled between the hands it is too wet and should be allowed to dry before
excavation continues.
ii. Excavation and backfill equipment should work from the surface where at all
practical to avoid compaction of the soils at depth .
iii. The bottom and sidewalls of the excavation should be left with a rough , open
surface. The appearance should be that of broken or ripped soil as opposed to a
sheared, smeared, or troweled surface. Any smoothed or smeared surfaces
should be removed with a toothed rake or shallow ripper taking care to remove
loose residues from the bottom of the excavation by hand if necessary.
1v. Care should be taken in placing till materials in the excavation to avoid
damaging the exposed soil surfaces.
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4.2 Operation -Maintenance and Inspections
• The owner shall install a structural barrier if necessary and take precautions to prevent
vehicular traffic, excessive surface watering, accidental flooding, or other activities in the
vicinity of the absorption field which may compact, saturate, or other wise alter the subsurface
soil parameters used in designing the septic system.
• The owner will plant and maintain grass or other shallow rooted cover crop to prevent erosion
and promote evapotranspiration over the absorption field.
• The owner will inspect and maintain the required mounding and drainage away from the
absorption field to prevent saturation from precipitation and surface flows.
• To mitigate the generation of preferential flow channels which may compromise the
operation of the system, the owner will inspect and prevent intrusion of burrowing animals
and deep rooted plants into the absorption field .
• The septic effluent filter shall be inspected and cleaned as necessary every six (6) months .
• The owner will conduct periodic maintenance of the septic system by removing accumulated
sludge from the septic tank every 3-4 years to prevent clogging of the absorption field.
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5.0 Limitations
This report is a site specific design for installation of an onsite wastewater treatment system and is
applicable only for the client for whom our work was performed. Use of this report under other
circumstances is not an appropriate application of this document. This report is a product of CCI
Engineering.ICronk Construction Incorporated and is to be taken in its entirety. Excerpts from this report
may be taken out of context and may not convey the true intent of the report. It is the owner's and owner's
agent's responsibility to read this report and become familiar with the recommendations and design
guidelines contained herein.
The recommendations and design guidelines outlined in this report are based on: I) the proposed site
development and plot plan as furnished to CCI Engineering.ICronk Construction Incorporated by the
client, and 2) the site conditions disclosed at the specific time of the site investigation of reference. CCI
Engineering.ICronk Construction Incorporated assumes no liability for the accuracy or completeness of
information furnished by the client. Site conditions are subject to external environmental effects and may
change over time. Use of this plan under different site conditions is inappropriate. If it becomes apparent
that current site conditions vary from those anticipated, the design engineer should be contacted to
develop any required design modifications. CCI Engineering.ICronk Construction Incorporated is not
responsible and accepts no liability for any variation in assumed design parameters.
CCI Engineering.ICronk Construction Incorporated represents this report has been prepared within the
limits prescribed by the owner and in accordance with the current accepted practice of the engineering
profession in the area. No warranty or representation either expressed or implied is included or intended
in this report or in any of our contracts.
Thomas A. Cronk, P.E .
. --~·,,__,_ 2 (). ')a].£
Date
NOTE: This indiviilual sewage disposal plan is meant to include the following four pages of
graphics including: 1) plot plan, 2) septic layout plan, 3) absorption field plan view, and 4)
absorption field cross section. The plan is not to be implemented in the absence of these related
graphics. In addition, results from the percolation test and soils evaluation arc included for
reference as Appendix A.
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NOTE
GRAVITY DISCHARGE or SE\/AGE
ErrLUENT rROM THE RESIDENCE
TO THE DISPOSAL SYSTEM IS
BASED ON THE rOLLO\/ING DESIGN
AS SUHPTIONS I
LENGTH or SEVAGE PIPING
rROM EXIT AT rOUNDATION
LINE TO ENTRY TO ABSORPTION
F"IELD = ISO' OR LESS
ELEVATION or GROUND SuRrACE
AT [NTRY TO ABSORPTION rlELD
NO MORE THAN G• ABOVE INVERT
ELEVATION or SEVAGE PIPE AT
EXIT rROM F"OUNDA TION LINE
DISCLAIMER
ff THESE DESIGN ASSUMPTIONS ARE
NOT UPHELD DURING CONSTRUCTION,
GRAVITY DISCHARGE CAN NOT BE
ASSURED AND A LlrT STATION HAY
BE RECUIRED
v canyon creek
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NOTE
THE rOLLO\JlNG SETBACKS MUST BE
SEPTIC
TANK
SPRINGS/IJELLS 50'
LAKE/STREAH/IRRIG. DITCH-so·
INTERMITTENT IRRIG. DITCH-10'
GATED PIPE ID'
SOLID PIPE/LINED DITCH --10'
DOMESTIC \/ATER CIST(RN -so·
DOMESTIC \/ATER LINE ---ID'
OCCUPIED STRUCTURE 10·
UNOCCUPIED STRUCTURE --5'
PROPERTY LINE 10'
t--1'
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MAINTAINED•
ABSORPTION
F"IELD
100· so·
25'
25'
IO'
JOO'
25'
20·
s·
10'
\
\
\
=\=
existing well
---=
NOTE
PROVIDE 4• CLEAN OUTS AT MAXIMUM
JOO' INTERVALS IN ALL EffLUENT
LINES EXCEEDING 100' IN LENGTH
NOTE
CALL Bil F"OR UTILITY LOCATES pr-ovlole nin. SCHD 40 PVC unoler~
au traFnc areas -encase ~
6' CHP or Flow f'HI with r>ln. 2'
high olensity foa,., insulation
over-at all points with less
thon 36' cover. typ.
absorption fielol consisting of 3
rows of 15 Oulck4 lnFlltrntors
Cor equlvnlent> For a totnl of
4S units conflgur-eol In serlnl
olistrlbutlon os shown
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\repnlr
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---1 ~ \-{unlineol ~2 acres •
lr-r-lgntlon ."/ e.
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i 510pe 20~·
olitch ?~('' ~
\~
\ \ STILLMAN PROJECT
\ \ SBO JB COURT. GLENVOOD SPRGS i
2123-253-00-048
'
\ SEPTIC LAYOUT PLAN
JUNE 30. 2016
\\ SCALE • J•=40' NORTH
\
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\\ \
\, \
\\ '
----... _
cir-Ive
= = !""""-i
.2SO gollon sep\ic tank
/effluent fKter\ COSI
oolel F"T\10444-3
serial distribution connection------,
designecl to assure saturation
of' upgradient trench before
ef'f'luent is 11Howed to flow to
adjacent clowngrndient trench
/
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/
-/
nnx. 3/1 C33%> slope
soil cap, provide
l"lin. 5% drolnoge
inspection/venting port
.......
ot each end or Infiltrator
trench
.......
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Ill
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-10·
I l11p1 J
disk or sco.rlf'y uncler . ; -40·
eoch inf'iltrotor trench !--36• --i /
,--Ct0'-12~ pref'er~ecl> ---i CUICK4 INF"ILTRATOR, insto.~ In occordnnce _/ /
with •JNFIL TRATOR TECHNICAL MANUAL•. / 113
STILLMAN PROJECT
ova~oble f'ron JnfUtro.tor Systl.'ns /
Inc .• 123 Eln Street. Suite 12, Old /
Saybrook, Connecticut 06475 '-/ -J - - - -
typical lnfiltrcitor trench
cross section <one of three>
ABSORPTION FIELD -CROSS SECTION <TYP. THREE OF THREE>
SCALE• 1 '=5'
ELEVATION DESIGN SPECltlCATIONS
OCSIGN DISTANCE fROM fOUNDATION LINE TO SEPTIC TANK = 12'
DESIGN DISTANCE fROM SEPTIC TANK TO SOIL TREATMENT AREA = 100'
ASSUMED ELEVATION OF' GROUND SURF'ACE AT ENTRY TO SOIL TREATMENT AREA = J00.00 '
ELEVATION OF' INFILTRATIVE SURFACE Of SOIL TREATMENT AREA = 96.oo·
INVERT ELEVATION OF' SE\JAGE LINE AT EXIT F'ROM SEPTIC TANK = 98.50'
INVERT ELEVATION Of SE\JAGE LINE AT EXIT fROM fOUNDATION LINE = 98.99'
SOILS LOG NOTES <EXCAVATION A>
-120·
SOILS LOG
<SEE NOTES>
580 JB COURT . GLEN\JOOD SPRINGS
2123-253-00-048 Ill -RED SAND/CLAYEY SAND <USDA-SANDY LOAM, BLOCKY, MODERATE STRUCTURE>
ABSORPTION fJELD -CROSS SECTION
JUNE 30, 2016
SCALE• 1"=5'
112 -LIGHT RED SAND/CLAYEY SAND CUSDA-LOAMY SAND, BLOCKY , MODERATE STRUCTURE>
113 -MINOR GRAVEL 00Mri-100MM> IN LIGHT RED SAND/CLAYEY SAND MATRIX
<USDA-SAND. SINGLE GRAINED>
NO GROUND\JATER OR HIGH SEASONAL WATER TABLE
TO 120' BELO'J GROUND SURF' ACE CBGS>
..,
APPENDIX A
SOILS AND PERCOLATION REPORT
CCI ENGINEERING/CRONK CONSTRUCTION INCORPORATED
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CCI ENGINEERING 1129 -24-Road
Cronk Construction Inc. Grand .Junction, CO 81505
Grand Junction (970) 245-0577 •Glenwood Springs/Aspen (970) 640-5029 •Montrose/Delta (970) 640-5029
Email: ccigj @ msn.com
Date:
Prepared by:
Client:
Property address:
Parcel No.:
Legal Descript.:
1.0 Soils Evaluation
SOILS AND PERCOLATION REPORT
June 28, 2016
Thomas A. Cronk, P.E.
I I 29 -24-Road
Grand Junction, CO 81505
245-0577
Royle Stillman
580 JB Court
Glenwood Springs, CO 81601
(970) 379-4027
580 JB Court, Glenwood Springs, CO 81601
2123-253-00-048
The site consists of approximately 8.72 acres of uncultivated native soil. Drainage is approximately 20%
to the west/southwest. A percolation test/soi Is evaluation was conducted on the property of reference on
06/28/16 by Tom A. Cronk, registered professional engineer (R.P.E.). The perc excavation trench
(excavation A) was located approximately 510' north of the south property line and approximately 200'
west of the east property line. Additional perc holes were located 40' north of the trench (excavation B)
and 50' south of the trench (excavation C).
A perc excavation trench (excavation A) was extended to a depth of 120" below ground surface (BGS).
There was no evidence of ground water or high seasonal water table in the open excavation to a depth of
I 20" BGS. The soils evaluation indicates three distinct soil horizons underlie the site. A lithological
description follows:
depth <in.)
O" -I 8"
18" -48"
48" -120"
description
sand/clayey sand, red ; (USDA-sandy loam, blocky, moderate structure)
light red sand/clayey sand (USDA-loamy sand, blocky, moderate structure)
minor gravel (I Omm-1 OOmm) in light red sand/clayey sand matrix (USDA-sand,
single grained)
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Pere holes were constructed in excavation A at a depth of approximately 36 in, in excavation B at a depth
of 48 in . and in excavation C at a depth of 40 in . The holes appeared to be well saturated at the time of
the test. Results of the percolation test are shown in Table I.
TABLE I
Percolalion Test Results
580 JB Court. Glenwood Snrings
Depth Time on 06128116 Time Pere
Drop Rate 11 :26 11 :41 11 :56 12:11 12:26 mi.Vin
(A) 36" -52'' 7.25 8.75 9.875 10 .5 11.375 6014 125 15
(8)48 .. -66" 7.375 9.25 10.75 dry 30/3 375 9
(C)40" -54" 7.375 8.5 9.625 10.0 11.5 60/4 .125 IS
2.0 Limitations
This document is representative of the site conditions disclosed at the specific time of the site
investigation . Site conditions are subject to change from external events both manmade (irrigation or
water feature construction) and naturally occurring (flooding or excessiv e precipitation). CCI
Engineering/Cronk Construction Incorporated is not responsible and acc epts no liability for any future
variation in site conditions.
CCI Engineering/C ronk Construction Incorporated represents this report has been pre pared within the
limits prescribed by the owner and in accordance with the current accepted practice of the engineering
profession in the area. No warranty or representation either expressed or implied is included or intended
in this report or in any of our contracts.
SEAL
Thomas A. Cronk, P.E .
Date J ''"'"' )o ,)d-6
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