HomeMy WebLinkAbout9C - Feasibility Study for CR 21 Watermain Replacement Project
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MEETING DATE:
AGENDA #:
PREPARED BY:
AGENDA ITEM:
DISCUSSION:
4646 Dakota Street S.E.
Prior Lake, MN 55372-1714
CITY COUNCIL AGENDA REPORT
JUNE 15, 2009
9C
STEVE ALBRECHT, DIRECTOR OF PUBLIC WORKS
CONSIDER APPROVAL OF A RESOLUTION ACCEPTING A FEASIBLlTY
STUDY FOR THE CR 21 WATERMAIN REPLACEMENT PROJECT
Introduction
The purpose of this agenda item is for the City Council to accept the feasibility
study for the CR 21 Watermain Replacement Project between Eau Claire Trail
and Quincy Street.
Historv
As the City Council is aware, during the. week of February 1st the City shut
down CR 21 for a period of three days to complete repairs to the 24-inch
diameter watermain located in CR 21 between Eau Claire Trail and Wagon
Bridge Circle. In 2007 the City completed a large repair to this watermain just
east of the Wagon Bridge. The total cost of repairs for these two events will
most likely exceed $100,000.
The 24-inch main is the City's largest watermain and provides one of three
east/ west connections from the east to west side of Prior Lake. The
watermain is ductile iron and was constructed in the late 70s. Under normal
conditions this main would be expected to have a 50+ year life. It is currently
about 30 years old. This main is especially important during high water use
periods and large fire events.
During the 2007 incident it was determined that a large rock placed during
construction of the bridge or roadway most likely created the hole in the main.
Over time the vibration of this rock against the pipe created a weak spot that
eventually failed. However an inspection of the pipe during the repair did not
indicate any other unusual wear on the pipe.
The repairs in 2009 revealed that the bottom side of the watermain was
corroded and failed due to vibration of small rocks near corroded areas. The
corrosion was most likely due to acidic soils in the area that over time reacted
with the ductile pipe and decayed the underside. In 2007 part of CR 21 was
reconstructed over a portion of the watermain. The pipe was insulated during
that project and no corrosion was noted on the top side of the pipe. This is
consistent with the repair findings. Based on City observation, it appears that
the cold winter with deep frost conditions of more than five feet in the roadway
may have also contributed to the failure. While the pipe did not freeze, the
frost reached to the insulation layer and created a connection transferring
vibrations from the roadway to the pipe and causing small stones to penetrate
the corroded sections of pipe. A total of three areas were repaired during this
latest episode.
www.cityofpriorlake.com
Phone 952.447.9800 / Fax 952.447.4245
On April 20, 2009 the City Council directed staff to complete a feasibility report
for the CR 21 Watermain Replacement Project.
Current Circumstances
Staff with the assistance of Bolton & Menke Braul"}Jhas completed a feasibility
study to evaluate the replacement options f6r the CR 21 Watermain
Replacement Project.
Staff evaluated four alternatives:
A. Complete replacement of the watermain in CR 21 boulevard using
traditional open cut trench construction;
B. Complete replacement of the watermain in the CR 21 boulevard using
directional drilling;
C. Slip line the existing 24" watermain using a fold and form liner;
D. Slip Line the existing 24" watermain by pulling a 16" HDPE pipe
through the existing watermain.
Alternative "A" is not considered feasible as it involves substantial impacts to
private property and the acquisition of substantial easements from three
adjacent property owners for construction. Alternative C is also not
considered feasible due to costs estimated to be $1,239,755.
Staff believes that Alternative "B" is the preferred option for the City with an
estimated construction cost of $814,000 plus easement costs. Staff believes it
is the preferred option for the following reason:
1) New watermain will be outside of existing roadway and is the best
long-term solution with minimal future impacts due to bridge or CR
21 reconstruction.
2) Minimizes future impacts to CR 21 and City repair costs.
3) Eliminates future fiber optic repair conflicts.
4) Minimizes impacts to CR 21 and private property.
5) Can be constructed as proposed with minimal contingencies.
Alternative "D" is feasible and potentially less expensive than "A" at an
estimated cost of $619,000. However, several issues make this a less
desirable option:
1) The existing 24-inch watermain must be removed from service
permanently for construction. The use of temporary watermains in
late fall is not desirable due to freezing issues. The existing
watermain must be cleaned prior to lining which will render the pipe
unusable due to its current condition. Additionally the cleaning
may impact water quality in the surrounding area due to
manganese.
2) This method can not traverse substantial bends which may require
several roadway excavations to facilitate lining. Additionally the
lining of the watermain under the lake may not be feasible
depending on the severity of the bends in the existing watermain of
which the City as-builds do not provide adequate detail. Because
these bends occur under the bridge they can not be excavated.
Should the City not be able to complete the section under the
bridge it will need to be directionally drilled adding about $50,000 to
$60,000 to the construction cost.
3) CR 21 will need to be excavated at each service location to allow
for connection to the new watermain.
4) In the future when CR 21 is reconstructed from Eau Claire to
Duluth including the bridge the watermain will most likely need to
be moved or lowered. This renders this option most likely a 15-25
year option and not a long-term option.
ISSUES:
Approximately 11,000 square feet of permanent easements are needed to
directionally drill the watermain. Should the residents be opposed to working
with the City on these easements the City would either need to consider
condemnation or completing Alternative "D." For that reason, as part of the
resolution for accepting this report, Staff is requesting authorization to begin
easement negotiations immediately. This will allow the City to work with
residents and determine whether easements can be acquired through
negotiations prior to proceeding with the project.
Staff is recommending the Council authorize SRF to begin negotiations on the
City's behalf with the impacted properties for a cost not to exceed $23,650 to
complete this work. Staff does not have the in-house expertise to negotiate
this type of easement in the timeframe needed or provide the needed survey
documents. SRF previously did a very good job of working with the Snell
property on watermain easement acquisition and provided excellent customer
service to both the resident and City.
In order to complete this project before winter and to allow for any needed
roadway restoration the City Council will need to authorize preparation of plans
and specifications at the July 20 meeting. Based on proceeding with
negotiations immediately staff believes we will have a good understanding of
whether final easement acquisition can be achieved through negotiations by
July 20.
FINANCIAL
IMPACT:
Depending on the alternative selected and potential easement and additional
costs this project will cost the City between $619,000 and $850,000. Funding
is available in the Water Fund for the project. Staff has already adjusted the
CIP and rate study fund balance assumptions in anticipation of this project
being completed this year.
ALTERNATIVES:
1. Approve a resolution accepting the feasibility report for the CR 21
Watermain Replacement Project.
2. Table the Resolution for a specific reason.
3. Deny the Resolution.
RECOMMENDED Alternative # 1
MOTION:
Reviewed by:
Frank Boyles, City Manager
4646 Dakota Street S.E.
Prior Lake, MN 55372-1714
RESOLUTION 09-XXX
RESOLUTION ACCEPTING THE FEASIBUTY REPORT FOR THE CR 21 WATERMAIN
REPLACEMENT PROJECT
Motion By:
Second By:
WHEREAS, The CR 21 watermain between Eau Claire Trail and Quincy Street is an important piece
of the City's water infrastructure; and
WHEREAS, Breaks occurring this past winter revealed that if left un-repaired the watermain will
most likely continue to fail annually at considerable cost to the City; and,
WHEREAS, The City Council accepts the feasibility report and approves the recommendation that
the City reconstruct the existing watermain in the CR 21 boulevard utilizing directional
drilling; and
WHEREAS, Replacement of the watermain utilizing directional drilling is the best method to address
the City's long-term needs while balancing impacts to CR 21 and residents; and
WHEREAS, In order to proceed with this method the City will need to acquire easements from three
properties and in order to meet project time constraints this work should begin
immediately; and
WHEREAS, The City does not have in-house expertise for acquisitions of this type and SRF has
previously provided a high level of service to the City and residents on these types of
acquisitions.
NOW THEREFORE, BE IT HEREBY RESOLVED BY THE CITY COUNCIL OF PRIOR LAKE,
MINNESOTA as follows:
1. The recitals set forth above are incorporated herein.
2. The Mayor and City Manager are authorized to execute the City's Standardized Professional
Services contract with SRF for an amount not to exceed $23,650 for easement acquisition.
3. Funding for these services shall come from account # 601-49400.
PASSED AND ADOPTED THIS 15th DAY OF JUNE 2009.
YES
NO
I Haugen
I Erickson
I Hedberg
I LeMair
I Millar
Haugen
Erickson
Hedberg
LeMair
Millar
Frank Boyles, City Manager
www.cityofpriorlake.com
Phone 952.447.9800 / Fax 952.447.4245
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COUNTY ROAD 21 W A TERMAIN
REPLACEMENT
PRELIMINARY REPORT
FOR THE CITY OF PRIOR LAKE
W ATERMAIN REPLACEMENT BETWEEN EAU CLAIRE TRAIL
AND QUINCY STREET
June 2009
COUNTY ROAD 21 W ATERMAIN
REPLACEMENT
PRELIMINARY REPORT
FOR THE CITY OF PRIOR LAKE
W A TERMAIN REPLACEMENT BETWEEN EAU CLAIRE TRAIL
AND QUINCY STREET
June 2009
I hereby certify that this Feasibility Report was prepared by me or under my direct supervision
and that I am a duly licensed Professional Engineer under the laws of the State of Minnesota.
.
J1r
Stephen Albrecht, P .E.
Reg. No. 41228
o/~
Date
INTRODUCTION
On April 20, 2008, the Prior Lake City Council adopted Resolution 09-064, which ordered the
preparation of a Feasibility Report for improvements to the project area listed below:
Replacement of the 24-inch watermain between Eau Claire Trail and Quincy
Street, Prior Lake, Minnesota.
SCOPE
This report evaluates the feasibility of replacing the existing 24-inch watermain between Eau
Claire Trail and Quincy Street. The results of that evaluation form the basis of the recommended
improvements. Cost estimates, funding strategies, and a proposed timeline are also explored in
this report.
BACKGROUND
During the week of February 15t the City shut down CR 21 for a period of 3 days to complete
repairs to the 24-inch diameter watermain located in CR 21 between Eau Claire Trail and Wagon
Bridge Circle. In 2007 the City completed a large repair to this watermainjust east ofthe Wagon
Bridge. The total cost of repairs for these two events will most likely exceed $100,000.
The 24-inch main is the City's largest watermain and provides one of three east west connections
from the east to west side of Prior Lake. The watermain is ductile iron and was constructed in
the late 70's. Under normal conditions this main would be expected to have a 50+ year life. It is
currently about 30 years old. This main is especially important during high water use periods and
large fire events.
During the 2007 incident it was determined that a large rock placed during construction of the
bridge or roadway most likely created the hole in the main. Over time the vibration of this rock /
against the pipe created a weak spot that eventually failed. However an inspection of the pipe
during the repair did not indicate any other unusual wear on the pipe.
In 2009 the repairs revealed that the bottom side of the watermain was corroded and failed due to
vibration of small rocks near corroded areas. The corrosion was most likely due to acidic soils in /
the area that over time reacted with the ductile pipe and decayed the underside. In 2007 part of
CR 21 was reconstructed over a portion of the watermain. The pipe was insulated during that
project and no corrosion was noted on the top side of the pipe. This is consistent with the repair
findings. It appears that the cold winter with deep frost conditions of over five feet in the
roadway based on City observation during construction may have also contributed. While the
pipe did not freeze, the frost reached to the insulation layer and created a connection transferring J
vibrations from the roadway to the pipe and causing small stones to penetrate the corroded
sections of pipe. A total of three areas were repaired during this latest episode.
PROPOSED IMPROVEMENTS
Based on the above history City Staff believes the watermain will continue to experience breaks
impacting the area as it did last winter. The cost of these continued breaks continues to escalate
and the replacement of the watermain is deemed the most cost effective solution.
The City evaluated four alternatives for replacement of the watermain. These alternatives
include:
A) Complete replacement of watermain with a new 16-inch PVC pipe in northern/eastern
boulevard of CR 21. Open trench construction will be used in combination with
directionally boring water services.
B) Complete replacement ofwatermain with new 18-inch (16-inch J.D.) HDPE pipe in the
northern/eastern boulevard using directional drilling as primary construction method.
C) Slip line the existing 24-inch watermain by using a structural 24-inch "fold and form"
lining product.
D) Slip line the existing 24-inch watermain by pulling through a separate 18-inch (16-inch
I.D.) HDPE pipe utilizing the existing watermain as a host pipe.
Alternative A
This alternative proposes to construct a new 16-inch PVC watermain in the shoulder of CR 21
and reconnect to the existing watermain at Quincy Street and Eau Claire Trail as shown in Figure
No.1 utilizing open trench construction. The replacement watermain is proposed to be 16-inch
which is smaller than the existing 24-inch watermain. As part of design staff reviewed the
connection points on both ends of this segment which are 16" watermains and determined that
the larger watermain did not provide any additional flow due to these restrictions. The proposed
PVC watermain will also be resistant to the soil issues currently experienced by the ductile iron
watermain. This option also includes directionally drilling 650 feet of 16-inch HDPE watermain
for the lake crossing. A detailed cost estimate has been completed for this alternative and is
attached in the appendix of this report. The total estimated cost excluding easements is
$729,280. This alternative is considered a long term or 50+ year design solution.
The primary concern with this method is the area of disturbance needed for construction. This
method will involve substantial easements and temporary easements from adjoining properties
along with increased restoration costs. This method also will involve the shut down of the
outermost lane of CR 21 for the duration of open trench portion of the proj ect.
..........._..~
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AlternatIve B./'
~-s-altern:a.1i~~ proposes to construct a new 18-inch (16-inch I.D.) HDPE watermain in the
..'northern/ eastern-lJoulevarctof"CK2T6TlitilizingClirediOnar'Cliimng'constfuctiOIl methods..... The
- watell11alll wiltb1rcofiIlectecl' fo....lIie....exlstlng..watennall1asshowii. iii"FiglireNc):'2at Bali .Claire
Trail and Quincy Street. This option reduces the amount of easement that is required
substantially. A detailed.. CO~-~s!iI?:ate...has .1Jeel'lc()fiiJilete(lfQtJut~:J!lt~matiYe.. and is....attache,ct .in
"'-the appenaixofthi~rel'ort:' the"!()ial..~~!!1E-~~~..4.22s,te~c!udillg ,e,as~Il1ellts i~J..~H,~JQ. This
alternative1Sconsidered a lon~..t~rm or 50+ yeaI'g~~ign: ..... . ..,......,......,...... ". .. .. .
This alternativ~so. inchtdes easem~I1t~J;?J!tr~4p.~~s~,Jhe.jmpacts.to...the..neighbQring"p:rQP~tlj~~
~:Ub~!~tjallYflUd...Qply.t~yp!y~~.jIlt~~!!~PtIQ~<lWl;:ly .....closures for construction. Directional
drilling construction methods are very dependent on site soils. For that reason soil borings were
completed by Braun Intertec and are included in the appendix to this report. The soils are
adequate however as with any directional drilling method contingencies need to be in place if
unexpected conditions are encountered.
Alternative C
This alternative proposes to slip line the existing 24" main using a structural "fold and form"
lining product. Figure 3 shows this alternative. The folded PE (polyethylene) pipe is pulled
through the existing pipe and then pressurized to expand to its full shape. Because the existing
watermain is corroding this pipe will need to have structural capabilities. Similar to the other
methods the service lines will need to be excavated. Because the pipe will remain in its current
location the traffic disruptions will be larger as it is in the middle of CR 21 in several areas. The
existing pipe needs to be cleaned prior to this process which means it will be take out of service
permanently as the existing pipe will most likely be damaged due to its corroded condition
during cleaning. The estimated cost of this option is $1,239,760. A detailed estimate is
contained in the appendix of this report. This is considered an interim 15-25 year solution as the
existing watermain will most likely need to be lowered or moved in the future when this segment
of CR 21 is reconstructed.
The primary issues with this method are the cost as the pipe material is extremely expensive and
the future need to move or modify the watermain does not make this a long term solution.
Temporary water services will also be required which is problematic in late fall due to
temperatures which could cause freezing.
Alternative D
J'w~'-!H~rnatiye p~(>p(>~~.~toslip liIle the 24-inch wate!TI1ain by pul!il1~aI11~~inch (l6-inch I.D.)
.P!P~Jg.2~gg!h~~X;i~!il1~~1~iIlch watenn(lig... Similartoalt~I:I:lativ~~."C'.' th~e:l(istiIlgpip~ )lJl.lstbe
cleaned.. 811~\Ym.nQJQIlg~rb~Jls~able. There will also be more roadway disruption as each
-serVice' needs to be excavated and potentially more excavations will be needed to pull the pipe
through the existing watermain. The existing voids between the new and old pipe will be blown
with sand and grouted. The total estimated cost of this option is $618,589 which is detailed in
the cost estimate included in the appendix to this document. ThisoI)tio~ i; also considered an
interim solution as most likely the existing watermain will either need to be modified or
relocated when this segment of CR 21 is reconstructed.
This .QPti.Q!lj~Jhe.Jl!Qst~Q~teff~.ctive jntQgJ!Y:~ dollars however it is not considered a long term ._0
'l'" . ""~""",,,.,,.~.,..,.~.,,,,,,=.,_._._.. .._.'...'......_.,....,._'....._... .....__'. ._'_. .._..,...,.,.'"""_,.:'"~..:::'''''',~~.."..>
~~~nair, , This option also presents an additional ris~a~. tl1~E~:p~~EI~x:~9tbe~~l?!~:J~.~~pul!~.~
through th~liiKe.~~~~~~?~L~~w~Ilt![1lle~:l(istil1gb~nds ar~ tQ~Qsev~r~,Tl1is co1.11c1 resultin~an
~adaitioi1a.r conti~g~n~Y- . QL$5 0,000 . to $60, 000 ,. to complete . that segment 'utilizing . directional
drilling and substantially more road disruption.
'"-
PROJECT SCHEDULE
Because this project involves disruption to the City's largest watermain it needs to be completed
between September and May due to water use. Based on last winters issues Staff also believes
the project needs to be completed by December 2009 to ensure breaks similar to last winter do
not occur. Any impacts to the CR 21 will need to be completed by early November to ensure
bituminous is available for paving. Based on these issues Staff proposes the following schedule
to complete this project.
June 15,2009
City Council accepts Feasibility Report & authorizes easement
negotiations
City Council Authorizes Preparation of Plans and Specifications
City Council Accepts Plans and Specifications & Authorizes
Advertisement for Bids
Open Bids
City Council Accepts Bids and Awards Standardized Contract
Construction Begins
Construction is Completed
July 20, 2009
August 3, 2009
August 31, 2009
September 8, 2009
September 21, 2009
December 1, 2009
FUNDING
Funding for this project is available in the Water Fund. Because this project involves
replacement of an existing watermain and is not required due to growth it will be funded by
water rates collected from existing residents.
CONCLUSION
All four alternatives are feasible. However alternatives "C" and "D" have higher degree of risks
and are not considered long term solutions. Based on the cost difference alternative "D" is the
best optio~" that JJ.lilizes,the existing pipe.
~-~-,
--------------- .
Alternative, . "]3" is,. preferre~ .. ove~.."I},,, qg~t9" t~c!l!S~c! .~~~~IIlen!.l~~~~s . ...~.~ ..substantiall)' .less
CIlstufbanceto" t~e.r~~14~rit~":~~4"Jg~dway,~ ". .... AI!~~~!iye~'l3,.~'~ls().i~ro'li4~~}he... best longt~rin
~solulioii as the pipe Will be essentially a continuous segment ofwatermain with no joints.
-." .. .,-".. .. ".', -' ';. .....-.'," ,-, ',: ,-i. " ,', " .,.1._,""'_ ", "'''<:'''':-.'.'.:.,. '-""'-"-'<>"'<""',-,::",'_'-'_":_",,_'_>'0<_ .__."".... ..~ .'.,.
,~a~<?c!~9g . Sll1~Yf!lllC;ltj.2JlQf Ipl1gtenn.benefitand.minimizillg41isrupti0114{}"resicleflts"illldm0torists
s!a.lfl>~lkves the City sh9uld.pursue alternative "B'? .Alternative "D" should be considered as a
contingency option if issues arise with easement acquisition.
PROPOSED WATERMAIN
PROPOSED CONSTRUCTION LIMITS --------
EXISTING WATERMAIN
EXISTING SANITARY SEWER
EXISTING STORM SEWER
o 150 300
~___ I
SCALE FEET
OBollon &: tAenk, Inc. 2009, All Rights Re.erved
H,\PLAl(\T1.'00n.\c.oD\~l.dwo ~/2fJ/fYt 10:41 em
1t\E30L TON &. MENK. INC.
Consulting Engineers &: Surveyors
tAANKATO. tAN fAlRtAONT, IAN SLEEPY EYE. tAN WlLLlAAR, tAN
BURNSVlu.E, tAN CHASKA, tAN RAlASEY, IAN AIAES, 'A
CITY OF PRIOR LAKE
CSAH 21/EAGLE CREEK AVE WATERMAIN REHABILITATION
OPTION 1 - OPEN TRENCH
MAY. 2009
FIGURE NO. 1
PROPOSED WATERMAIN
PROPOSED CONSTRUCTION LIMITS --------
EXISTING WATERMAIN
EXISTING SANITARY SEWER
EXISTING STORM SEWER
o
150
r""'I.r- ...,r,
SCALE FEET
OBollon '" Menk, Inc. 2009, All Rights Reoerved
H.\I'tAI(\T1.'OOT7.\CAIl\~"" '/28/09 '0..,...
300
CIIY OF PRIOR LAKE
CSAH 21/EAGLE CREEK AVE WATERMAIN REHABILITATION
OPTION 2 - DIRECTIONAL DRilLING
MAY, 2009 FIGURE NO. 2
1\BOL TON &. MENK. INC.
Consulting Engineers &: Surveyors
MANKATO, MN FAlRMONT. MN SLEEPY EYE, MN W1LLIAAR. MN
BURNSVIUE, MN CHASKA. MN RAMSEY, MN AMES, LA
PROPOSED WATERMAIN REHAB
PROPOSED CONSTRUCTION LIMITS
EXISTING WATER MAIN
EXISTING SANITARY SEWER
EXISTING STORM SEWER
o 150 300
r-..-_- I
SCALE FEET
CBollon '" lAenk, Inc. 2009, All Rights Reserved
H,\l'tAI(\T1S10077l\CM\~ "/20/119 10,.,,,
~E30L TON & MENK. INC.
Consulting Engineers & Surveyors
IAANKATO. IAN fAlRMONT, IAN SLEEPY E'tE, IAN WlLLlAAR. IAN
BURNSV1UE, IAN CHASKA, IAN RAlASEY, IAN AIAES, IA
CITY OF PRIOR LAKE
CSAH 21/EAGLE CREEK AVE WATER MAIN REHABILITATION
OPTIONS 3 & 4 - REHABILITATION OF EXISTING PIPE
MAY, 2009 FIGURE NO. 3
APPENDIX
City of Prior lake
CSAH21 Watermain Rehabilitation! Reconstruction
May 28, 2009 V/
Alternative 2: Complete Replacement Utilizing Directional Drilling
Bid Item Unit Approx Unit Total
Quantity Price Cost
.w..__ .-
18" HOPE DR 11 - Directionally Drilled loF. 1395 $125.00 $174,375.00
Directionally Drilled Lake Crossing loF. 650 $165.00 $107,250.00
Drilling Obstruction Contingency 1 $50,000.00 $50,000.00
IDewatering - Setup & Recovery Pits EACH 2 $5,000.00 $10,000.00
16" DIP Watermain, Class 52 loF. 120 $30.00 I $3,600.00
116" Butterfly Valve & Box EACH 4 $18,750.00 I $75,000.00
110" Gate Valve & Box EACH 1 $1,200.00 I $1,200.00
18" Gate Valve & Box EACH 2 $800.00 I $1,600.00
16" Gate Valve & Box EACH 3 $600.00 j $1,800.00
IHydrant (8' Bury) EACH 3 $2,500.00 $7,500.00
IWatermain Fittings LBS 3150 $4.00 $12,600.00
IConnect to Existing Watermain EACH 5 $1,000.00 $5,000.00
11.5" Type K Copper Water SelVice loF. 160 $105.00 $16,800.00
/1.5" Corporation Stop EACH 4 $170.00 $680.00
/1.5" Curb Stop & Box EACH 4 $560.00 $2,240.00
IAggregate Bedding TON 15 $25.00 $375.00
IConcrete Curb and Gutter loF. 400 $12.00 $4,800.00
IBituminous Patch S.Y. 1930 $29.50 $56,935.00
ISeed & Mulch ACRE 0.75 $1,500.00 $1,125.00
IErosion Control- Floating Silt Fence loF. 250 $5.00 $1,250.00
IErosion Control - Silt Fence loF. 500 $2.50 $1,250.00
Ilnlet Protection EACH 10 $350.00 $3,500.00
IAbandon 24" Watermain (In Place) loF. 2000 $5.00 $10,000.00
/Temporary Water SelVice EACH 29 $175.00 $5,075.00
ITraffic Control loS. 1 $10,000.00 $10,000.00
I
ITotal Estimated Construction Cost j $563,955.00 I
5% Mobilization I $28,197.75 I
10% Construction Contingencies I $59,215.28 I
25% Project Soft Costs I $162,842.01 I
I Total Estimated Project Cost I-=-. $814,210.03 J
------
City of Prior lake
CSAH21 Watermain Rehabilitation/ Reconstruction
May 28, 2009
Alternative 3: Slip Lining With "Fold and Form" Product
I Bid Item Unit Approx Unit Total
Quantity Price Cost
I ,
124" Fold and Form Slip Lining L.F. 2000 $325.00 $650,000.00
6" DIP Watermain, Class 52 L.F. 120 $30.00 $3,600.00
124" Butterfly Valve & Box EACH 2 $24,500.00 $49,000.00
116" Butterfly Valve & Box EACH 2 $18,750.00 $37,500.00
10" Gate Valve & Box EACH 1 $1,200.00 $1,200.00
8" Gate Valve & Box EACH 2 $800.00 $1,600.00
6" Gate Valve & Box EACH 3 $600.00 $1,800.00
Hydrant (8' Bury) EACH 3 $2,500.00 $7,500.00
Watermain Fittings LBS 3450 $4.00 $13,800.00
Connect to Existing Watermain EACH 5 $1,000.00 $5,000.00
1.5" Type K Copper Water Service L.F. 160 $105.00 $16,800.00
1.5" Corporation Stop EACH 4 $170.00 $680.00
1.5" Curb Stop & Box EACH 4 $560.00 $2,240.00
Aggregate Bedding TON 5 $25.00 $125.00
Concrete Curb and Gutter L.F. 400 $12.00 $4,800.00
Bituminous Patch S.Y. 1580 $29.50 $46,610.00
Seed & Mulch ACRE 0.25 $1,500.00 $375.00
Erosion Control- Floating Silt Fence L.F. 250 $5.00 $1,250.00
Erosion Control- Silt Fence L.F. 500 $2.50 $1,250.00
Ilnlet Protection EACH 10 $350.00 $3,500.00
IT emporary Water Service EACH 29 $175.00 $5,075.00
Traffic Control L.S. 1 $5,000.00 $5,000.00
Total Estimated Construction Cost $858,705.00
5% Mobilization $42,935.25
10% Construction Contingencies $90,164.03
25% Project Soft Costs $247,951.07 I
Total Estimated Project Cost $1,239,755.34
City of Prior lake
CSAH21 Watermain Rehabilitation! Reconstruction
May 28, 2009
Alternative 4: Slip Lining with 18" HDPE
Bid Item Unit Approx Unit Total
Quantity Price Cost
------, ---
Slip Line Installed 18" HOPE DR11 L.F. 2000 $110.00 $220,000.00
6" DIP Watermain, Class 52 L.F. 120 $30.00 I $3,600.00
Clean Existing Pipe L.F. 2000 $5.00 ! $10,000.00
16" Butterfly Valve & Box EACH 4 $18,750.00 $75,000.00
110" Gate Valve & Box EACH 1 $1 ,200.00 $1,200.00
18" Gate Valve & Box EACH 2 $800.00 $1,600.00
16" Gate Valve & Box EACH 3 $600.00 $1,800.00
IHydrant (8' Bury) EACH 3 $2,500.00 $7,500.00
IWatermain Fittings LBS 3450 $4.00 $13,800.00
IConnect to Existing Watermain EACH 5 $1,000.00 $5,000.00
11.5" Type K Copper Water Service L.F. 160 $105.00 $16,800.00
11.5" Corporation Stop EACH 4 $170.00 $680.00
11.5" Curb Stop & Box EACH 4 $560.00 $2,240.00
IAggregate Bedding TON 5 $25.00 $125.00
IConcrete Curb and Gutter L.F. 400 $12.00 $4,800.00
IBituminous Patch S.Y. 1580 $29.50 $46,610.00
ISeed & Mulch ACRE 0.25 $1,500.00 $375.00
IErosion Control - Floating Silt Fence L.F. 250 $5.00 $1,250.00
IErosion Control- Silt Fence L.F. 1000 $2.50 $2,500.00
jlnlet Protection EACH 10 $350.00 $3,500.00
Temporary Water Service EACH 29 $175.00 $5,075.00
IT raffic Control L.S. 1 $5,000.00 $5,000.00
ITotal Estimated Construction Cost $428,455.00
5% Mobilization $21,422.75
10% Construction Contingencies $44,987.78
25% ProJect Soft Costs $123,716.38
I Total Estimated Project Cost $618,581.91
-.J / I
-
/ W
/ -1
( U ,
~
u ,
\ a I
"-
"- \ 4080 GRAlNWOOD CIR. NE I 0
'" #15717 EAGLE CREEK AVE. \. PERMANENT EASEMENT 0
AREA-3490 SF (0.08 AC) $
I 2: ,
<( I
-1-1-1-
PROPOSED WATERMAIN
pRioR iJ.i<(
LEGEND
,--------l
I I
L________J
PROPOSED PERMANENT EASEMENT
o 50 100
I'""'--~___ I
SCALE
FEET
AI\BOLTON &. MENK. INC.
I ( Consulting Engineers & Surveyors
tAANKATO. tAN FAIRtAONT. tAN SLEEPV EYE, tAN W1UJAAR, tAN
" BURNSVlLIL tAN CHASKA. tAN RAtASEY, tAN AlAES, IA
CITY OF PRIOR LAKE
CSAH 21/EAGLE CREEK AVE WATERMAIN REHABILITATION
OPTION 2 - DIRECTIONAL DRILLING
@Bolton & Menk. Inc. 2009, All Rights Reserved
H:\PLAK\T16100nB\FEAS\PROP WI.AN.dwg 5/28/09 11:13 om
MAY, 2009
FIGURE NO. 4
!~,
I 115795 EAGLE CREEK AVE.
PERMANENT EASEMENT
AREA=3140 SF (0.07 AC)
?
~.
/-1/
y/
-I
-1-1-1-
PROPOSED WAlERMAIN
\3.~ _
.~~Ic
-- ~;G~.' , 0 ()--
.il:~5~1
.'1 iI;, ...
". 'v
LEGEND
,--------,
I I
L________.J
PROPOSED PERMANENT EASEMENT
o 50 100
r---_- I
SCALE FEET
@Bolton & Menk, Inc. 2009. All Rights Reserved
H:\PLAK\T16100nB\FEAS\PROP WMN.dwg 5/28/09 11:13 om
1\E30L TON &. fV1ENK. INC.
Consulting EngIneers &. Surveyors
IAANKATO. IAN FAIRIAONT. IAN SLEEPY EYE. IAN WILLl.4AR. IAN
BURNSVILLE. t.tN CHASKA, IAN RAIASEY. IAN AMES, IA
CITY OF PRIOR LAKE
CSAH 21/EAGLE CREEK AVE WATERMAIN REHABILITATION
OPTION 2 - DIRECTIONAL DRILLING
MAY, 2009
FIGURE NO. 5
\,
LEGEND
-1-1-1-
PROPOSED WATERMAIN
,--------,
I I
L________.J
PROPOSED PERMANENT EASEMENT
o 50 100
r---_- .,
SCALE FEET
@Bolton & Menk. Inc. 2009. All Rights Reserved
H:\PLAK\T161D0778\FEAS\PROP WMN.dwg 5/28/09 11:13 em
A~E30LTON &. MENK. INC.
III Consulting Engineers & Surveyors
MANKATO. MN FAIRMONT. MN SLEEP'( EYE. MN WILLI.4AR. MN
. I BURNSVILLE. MN CHASKA. MN RAMSEY. MN AMES. 'A
CITY OF PRIOR LAKE
CSAH 21/EAGLE CREEK AVE WATERMAIN REHABiLiTATION
OPTION 2 - DIRECTIONAL DRilLiNG.
MAY. 2009
FIGURE NO. 6
BRAUN
INTERTEC
Bl'Gun Interlel: CorpOl'Gtion I Phone: 952.995.2000
11001 Hampshire Avenue S Fax: 952.995.2020
Minneapolis, MN 55438 Web: braunintertec.com
May 11, 2009
Project BL-09-01027
Mr. Steve Albrecht
City of Prior lake
17073 Adlemann StreetSE
Prior lake, MN 55372
Re: Directional Drilling Suitability
CSAH 21/ Eagle Creek Ave Water Main Rehabilitation
Eagle Creek Ave - Eau Claire Tra'if to Quincy Street
Prior Lake, Minnesota
Dear Mr. Albrecht:
We are providing additional recommendations to supplement our geotechnical evaluation report dated
May 4, 2009 based on a request from Marcus Thomas of Bolton & Menk. Mr. Thomas requested
additional information sp.ecific to the suitability to directional drilling for this project
Directional drilling is suitable for instillation of utilities on this site project provided the contractor has
selected the appropriate methods, equipment and has staff that are experienced in drilling in the
conditions encountered by our soil borings. COl1t'ractors should be aware that the soils on site include
glacial till soils. Some of the glacial till soils are relatively stiff or dense and may contain cobbles or
boulders. Lake deposits are present are soft or loose and saturated that are susceptible to blowout if the
contractor uses inappropriate instillation methods. Water bearing sands are present that are relatively
permeable.
We recommend that project be set up as a performance based project. (fadditional compensation for
obstructions is available under the contract, the definition of an obstruction should be defined and rates
and terms of compensation should be listed.
Thank you for making Braun Intertec your geotechnical consultant for this project. If you have questions
about this report, or if there are other services that we can provide you, please call Chris Kehl at
952.995.2386 (ckehl@braunintertec.com).
Sincerely,
BRAUN INTERTEC CORPORATION
Professional Certification:
I hereby certify that this plan, specification, or report
was prepared by me or under my direct superviiiiUhl
and that I am a duly licensed professiona~~~~lMf';7;~,~
~nde e laws of the~State of intleso~..~~~."."...~~
#? ~ ~... .. ~ ..,,~
~ /t?-, . lc::!CHFlIsToPHERR.\a:~
Christopher R Kehl PE ~ 0: KEHL, PE :w::
. I . :rt\~ .IU:-
Project Engineer S~.. 43459 lJ!i
~ C(\.. .~;::;
license Number: 43459 '~QA.. ...tq.~
May 11, 2009 b(. ~~"/~~~SS~l\~'\\*~
~ :tIIIlIJlIUII\'\\\'\/
~A': .0 -<... J
R A. H r, PE
Vice President - Principal Engineer
,..
lI11"rrllc Thorn"", RnltQn R. l\Il",nk-
& Providing engineering and environmental solutions since 1957
Geotechnical Evaluation Report
CSAH 21/ Eagle Creek Ave Water Main Rehabilitation
Eagle Creek Ave - Eau Claire Trail to Quincy Street
Prior lake, Minnesota
Prepared for
City of Prior lake
Professional Certification:
I hereby certify that this plan, specification, or report
was prepared by me or under my direct supervision
and that I am a duly licensed Professional Engineer
under the laws ofthe State of Minne~~811l"III1~l'
~'1ff'.. OF M!N~/'''1.
4 ~~~........:!.~'~
~li... ..p;..~
,,~~ A .. .~~
R.~~l:'!CHRISTOPHER R.~ '%
~ ~! KEHL. PE . :ffi ~
~~. ..~-
Christopher R. Kehl, PE ~~..'43459 .~~
~'a. ..~;:::
Project Engineer '\ 4:.. ...~~~"
~ "0 ........~\. ~
License Number: 43459 ~/"'ll!ESS\O~'t..~\''*
May 4.2009 1JJlIIU1Ii'\W- . ,
Project Bl-09-0t027
Brau~ l!1tertec Corporation
: '.~' :.~.:
J. ". .: : . . : I ~., i ': ", . .... :.....~. .'.
. .'"-
BRAUN
INTERTEC
May 4, 2009
Mr. Steve Albrecht
City of Prior Lake
17073 Adlemann Street SE
Prior Lake, MN 55372
Re: Geotechnical Evaluation
CSAH 21/ Eagle Creek Ave Water Main Rehabilitation
Eagle Creek Ave - Eau Claire Trail to Quincy Street
Prior Lake, Minnesota
Dear Mr. Albrecht:
Braun Inlenee Corporation
11001 Hampshire Avenue S
Minneapolts, MN 55438
Phone: 952.995.2000
Fox: . 952.995.2020
Web: brauninlernoc.com
Project BL-09-01027
We are pleased to present this Geotechnical Evaluation Report for the water main replacement on Eagle
Creek Ave from Eau Claire Trail to Quincy Street. A summary of our results and our recommendations is
presented below. More detailed information and recommendations follow in the report.
Summary of Results
Based on the soil borings the site could generally be described as soft lacustrine (lake deposited) soils
over stiffer glacial deposits. Depending on the final alignment of the water line the soils could encounter
very loose to medium dense sands, very soft to very stiff clays, and soils above and below the water
table. Within the glacial soils gravel, cobbles and boulders should be expected.
Groundwater was encountered as high as elevation 902 and the water level of the lake is 900.
Remarks
Thank you for making Braun.lntertec your geotechnical consultanHor this project. If you have questio.ns
about this report, or if there are other services that we can provide you, please call Chris Kehl at
952.995.2386 (ckehl@braunintertec.com).
Sincerely,
BRAUN INTERTEC CORPORATION
~~;a(
Christopher R. Kehl, PE
Project Enginee~ /? /f ~
c/P~~~
Ray A. Huoer, PE
Vice President - Principal Engineer
c: Marcus. Thomas, Bolton & Menk
GeoRpt-Water Main Rehabilitation
;.; Providing engineering and en'Vironmental solutions since 1957
Table of Contents
De~criptlon
Page
A. I ntrod uction ...... ....... ....... .... ............ ........... ............. ...... ....... ......... ....... ........ ............... ........ ...... ....... 1
A.i. Project Description.... ........... ............. ........ ....... ......... ......... .............................. ...... ............. 1
A.2. Background Information and Reference Documents.......................................................... 1
A.3. Scope of Services.. ............ ....... ....... ............................................. ...:.. .........,.... ...... ............. 1
A.4. Staking and Surveying....... .......... ..:... ..................... ......... ..... .......... ........... .... ...................... 2
B. Re suIts................................ ........... ......................... ................. ............. .................. ..:....................... 2
B.l. Exploration logs......... ............... ................. ........... ....... .......... ..... .......... ........ .......... ............. 2
B.l.a. log of Boring Sheets ... .......... .......................................................... ....................... 2
B.l.b. Geologic Origins ......;... ......... ........................ ..... ....... ........ ... .... ....... ...... ........... ....... 3
B.2. Geologic Profile........, ....'.'111I....'1... ....., .., ''''1' ,....., 1'1."""1' ..... I' ..........,........., ""1 I"""'" ...... ....,.. 3
. B.2.a. Fill......... ..... .......... ... .............: .......... ......: .... ..... .... ...... ........... ....... .......... ..... ...... ....... 3
B.2.b. La custrine Deposits... .... ...... ................................ ................ ....... .... ...... ..... ........ ..... 3
S.2.c. Glacial Deposits.... ........ ............ ..... ........... ..... ....... ..... ................ ........ ....... ;............ 3
S.2.d. Groundwater ..... ............. .......... ....... ................ ...;...................... .......... ..... ............. 4
C. Recom mendations. ..... ..................... :.~;.:.. .:..... .......;....... ....... .......... ..... .................. ............... .. ........... 4
C.1. Design and Construction Considerations ...........................................................................4
C.2. Site Grading and Building Subgrade Preparation .................................................. ............. 5
C.2.a. Excavation Support................... ................ ..... ....... ........ ......... .... .......... ..... ............. 5
C.2.b. Selecting Excavation Backfill and Additional Required Fill..................................... 5
C.2.c. Placement and Compaction of Backfill and Fill..................................................... 6
D. Proced ures ..... ................ ......................... ............. ..... ......... ....... .......... ....................... .................. .... 6
0.1. Penetration Test Borings ....... .......... .... ............ ....... .................... ... ... .... .......... ....... ............. 6
D.2. Material Classification a nd Testing.. ...... .............. ................. ........... ............ .............. ......... 7
D.2.a. Visual and Manual Classification .....:....................................................................... 7
D.2.b. Laboratory Testing.... ...................................................... ..................... ..... ............. 7
0.3. Groundwater Measurements ................. ............................. ..................................... ..........7
E. Qualifications..... ............. ........... ..... .... ........... ........................... ............. ......... .... .... ............ ... ..... ..... 7
E.l. Variations in Subsurfa ce Conditions .............. ...:........................................ ......... ......... ....... 7
E.1.a. Materia I Strata. ...... ............. ..... ..................................................... ............ ............. 7
E.1.b. G ro undwater Levels....................... ....... ................. ........... ...... ...... ......... ........ ........ 8
E.2. Continuity of Professional Responsibility ..............................:............................................8
E.2.a. Pia n Review. ........... ............ ......... ..... .............. ........ .............. .... ........ ......... ,............ 8
E.2.b. Construction Observations and Testing ................................................................ 8
E .3. Use of Report....... ........ .................. ....... ....... ......... ............... .................... .......... ...... ..... ........ 8
E.4. Standa rd of Care.... ........ ......................... ...... ........ ....... ........ ..... .......... .... ..... .......... ............. 8
Appendix .
Boring Location Sketch
Log of Boring Sheets ST-l to ST-7
Descriptive Terminology
BRAUN
INTERTEC
A. Introduction
A.i. Project Description
. .
The City of Prior lake is proposing to reconstruct the water ma in on Eagle Creek Avenue from Eau Claire
Trail to Quincy Street. It is anticipated that much of the utility line will be constructed using directional
drilling (also known as horizontal drilling or trenchless utility construction). Some of water line will be
installed in or adjacent to Prior lake.
The purpose of this geotechnical evaluation is to assist the City of Prior lake and their design team in
evaluating th~ soil and groundwater conditi~ns in the area of the proposed development and to provide
recommendations for design and construction of utilities.
A.2. Background Information and Reference Documents
. To facilitate our evaluation, we were provided with an aerial photograph showing approximate location
of utilities. We were later provided with a CAD file to prepare the attached sketch.
A.3. Scope of Services
Our scope of services for this project was originally submitted as a Proposal to City of Prior lake dated
March 19, 2009. We received authorization to proceed from the City of Prior lake on April 21. Tasks
completed in accordance with our authorized scope of services are described below. The nature of and
factors contributing to deviations from our proposed scope of services are also noted.
Our scope of services was limited to:
.
Selecting and staking the boring locations and determining ground surface elevations at the
boring locations.
.
Coordinating the locating of underground public utilities nea r the boring locations.
BRAUN
. INTERTEC
!
I. City of Prior lake
Project BL-09-01027
May 4, 2009
Page 2
· Conducting the following standard penetration test borings:
· Three borings with a truck rig at Eagle Creek Avenue from Eau Claire Trail, extending
them to 20 feet below existing gra~e. One of these borings was changed to a barge
mounted boring due to conflicts with utilities.
· Three borings with a skid mounte~ rig from a barge into Prior lake, North of Eagle Creek
Ave, extending them to 15 feet below the lake bottom.
· One boring with a truck rig at Eagle Creek Ave and Quincy Street, extended to 20 feet
'below existing grade.
· Classifying the samples and preparing boring logs.
· Formulating recommendations for utilities. .
· Submitting a geotechnical evaluation report containing logs of the borings, our analysis of
the field and laboratory tests, and recommendations for design of utilities.
A.4. Staking and Surveying
Exploration locations and surface elevations at the exploration Jocations were determined using GPS
(Global Positioning System) technology that utilizes the Minnesota Department ofTransportation's
permanent GPS Virtual Reference Network (VRN). Prior to commencing with our subsurface exploration
activities, we coordinated the clearing of the exploration locations of underground utilities through
Gopher State One Call.
. B. Results
B.l. Exploration Logs
B.1.a. Log of Boring Sheets
log of Boring sheets for our penetration test borings are included in the Appendix. The logs identify and
describe the geologic materials that were penetrated, the results of penetration resistance and
groundwater observatic;>ns.
BRAUN
I NTE RTEC
City of Prior Lake
Project BL-09-01027
May 4, 2009
Page 3
Strata boundaries were inferred from changes in the penetration test samples and the drill auger
cuttings. Because sampling was not performed continuously, the strata boundary depths are only
approximate. The boundary depths likely va ry away from the boring locations, and the boundaries
themselves may also occur as gradual rather than abrupt transitions.
B.l.b. Geologic Origins
Geologic origins presented for each stratum on the log of Boring sheets are based on the soil types,
blows per foot, and available common knowledge of the geological history of the site. Because of the
complex glacial and post-glacial depositional environments, geologic origins ca~ be difficult to ascertain.
A detailed investigation of the geologic history of the site was not performed.
. B.2. Geologic Profile
The types of soils encountered in the borings are described below. The soils are generally described in
the order they were encounteredj i.e., beginning at the ground surface. Please see the soil boring logs in
the appendix for a more in depth summary of the observed soils.
B.Z.a. Fill .
limited topsoil fill was encountered.at the boring locations on land with thicknesses of less than 1 foot.
The topsoil encountered in this area typically consisted of silty sand, clayey sand, arid lean clay.
The borings encountered fill.at 2 of 7 boring locations to depths of 4 to 7 feet below the surface. The fill
at the borings consisted of silty sand and lean clay. The penetration resistances recorded in the fill varied
from 3 to 6 blows per foot (BPF).
B.Z.b. Lacustrine Deposits
The borings encountered lacustrine {lake} deposits consisting of silty sand, clayey sand, silty clay and lean
clay in 5 of the 7 of the borings. The penetration resistances recorded in the cohesionless (sand) soils
varied from 2 to 4 BPF, indicating a very loose relative density. The penetration resistances recorded in
the cohesive (clay) deposits varied from weight of hammer to 5 BPF, indicating a very soft to rather soft
consistency.
B.Z.c. Glacial Deposits
The borings encountered glacial deposits consisting of poorly graded.sand, poorly graded sand with silt,
silty sand, clayey sand, silty clay, sandy lean clay and lean clay. The penetration resistances recorded in
BRAUN
I NTERTEC
i
! .
City of Prior lake
Project Bl-09-01027
May 4, 2009
Page 4
the cohesionless (sand) soils varied from 9 to 14 BPF, indicating a loose to medium dense relative
density. The penetration resistances recorded in the cohesive (clay) glacial tills varied from 4 to 28 BPF,
indicating a rather soft to very stiff consistency. Some of the recovered samples contained gravel. Gravel,
cobbles and boulders should be anticipated in glacial deposits
B.2.d. Groundwater
Groundwater was measured to be at' elevations of 898 to 902 in 6 of the 7 borings at the time of drilling.
In boring ST -7, water was not obseNed over the relatively short term of boring monitoring. In clayey
soils, groundwater will take several days to stabilize in the boreholes.
The level of Prior lake at the time of drilling was near elevation 900.1. The highest measured level of the
lake was at 905.7 in 1983.
Perched wate~ may occur at higher elevations across the site especially in fill. In clayey soils,
groundwater will take several days to stabilize in the boreholes.. However,. the boreholes were
immediately backfilled. Seasonal and annual fluctuations of groundwater, however, should be
an~icipated .
C. Recommendations
C.l. Design and Construction Considerations
We understand the project will consist of replacement of a waterline. Portions of the project will extend
through Prior Lake and will utilize directional driUing. Portions of utility construction on land will either
utilize directional drilling or conventional excavate and refill techniques. Pits may be constructed to ease
horizontal drilling construction.
Excavations are anticipated to penetrate the groundwater surface at an elevation of 900 or higher.
Depending on the depth below the water table and the types of soils exposed the extents of dewatering
on the project could vary greatly. For example excavations into the sand layers encountered in borings
ST-l and ST-2 would likely require well points and/or sheet piling to limit water intrusion. Conversely due
to the higher elevation and clay soils at boring ST-7 dewatering may consist of occasional use of sump
pumps.
BRAU'"
INTERTEC
City of Prior Lake
Project BL-09-01027
May 4, 2009
Page 5
Soils excavated from pits may require drying prior to replacement ifthe soil is to be used as engineered
fill. Ifthe pits are constructed in green area~ where subsidence is not an issue, it may be more cost
effective to backfill the soils as is and regrading the area the following year.
Contractors should be aware that the soils on site include glacial till, soils some of which are relatively
stiff or dense and may contain cobbles or boulders. Deposits of lake deposits are present are soft or
loose and saturated.
The soils encountered by the borings are generally considered moderately corrosive to metallic conduits.
We recommend specifying no corrosive materials or providing corrosion protection unless additional
tests are performed to demonstrate that the soils are not corrosive.
We'~ave attempted to describe our understanding of the proposed construction to the extent it was
reported to us by others. Depending on the extent of available information, assumptions may have been
made based on our experience with similar projects. If we have not correctly recorded or interpreted the
project details, we should be notified. New or changed information could require additional evaluation,
analyses and/or recommendations.
C.2. Site Grading and Building Subgrade Preparation
C.2.a. Excavation Support
There a variety of soil conditions and water conditions on site. An OSHA approved competent person
should review this soil classification in the field at individual work areas. Excavations must comply with
the requirements of OSHA 29 CFR, Part 2926, Subpart P, "Excavations and Trenches." This document
states that excavation safety is the responsibility of the contractor. Reference to these OSHA
requirements should be included in the project specifications.
C.2.b. Selecting Excavation Backfill an~ Additional Required Fill
In areas where the fill will be in a 1 to 1 oversize of a road we recommend initially backfilling over wet or
submerged excavation bottoms with at least 2 feet of coarse sand having less than 50 percent of the
particles by weight passing a #40 sieve, and less than 5 percent of the particles passing a #200 sieve. In
landscape areas initial backfilling with sand is not required. We should be further consulted if will be
required adjacent to structures.
On-site soils free of organic soil and debris can be considered for reuse as backfill and fill. The fine-
grained soil will be more difficult to compact if wet or allowed to become wet, or if spread and
BRAUN
I NTERTEC
City of Prior Lake
Project BL-09-01027
May 4, 2009
Page 6
compacted over wet surfaces. If winter excavation and filling activities are planned, consideration may be
given to using clean, coarse sand conforming to Mn/DOT Specification 3149.2B for Select Granular
Borrow for backfill in place of trying to backfill with frozen soil, unless substantial subsidence ofthe soils
can be tolerated.
C.2.c. Placement and Compaction of Backfill and Fill
We recommend spreading backfill and fill in loose lifts no thicker than 12 inches. We recommend
compacting backfill and fill in accordance with the criteria presented below in Table 1. The relative
compaction of utility backfill should be evaluated based on the requirements of the structures or
pavement above the utility line, and vertical proximity to that structure.
Table 1. Compaction Recommendations Summary
. --.- -"-~-...
-- .- .-- -
Reference
Below pavements, within 3 feet
of subgrade elevations
Below pavements, more than 3
feet below subgrade elevations
Below landscaped surfaces
Recommended
Soil types for fill
Non-Organic Mineral soils,
Ideally Granular
Relative
Compaction,
minimum percent
(ASTM D 698 -
standard Proctor)'
Moisture Content
Variance from
Optimum, percentage
points
100
+/-1.
Non-Organic Mineral soils
95
+/-3
Mineral soils or topsoil
90 _.J_.
+/- 4
D. Procedures
0.1. Penetration Test Borings
The penetration test borings were drilled with a truck and barge -mounted core and auger drill equipped
with hollow-stem auger. The borings were performed in accordance with ASTM D 1586. Penetration test
sampl!=s were taken at 2 1/2- or 5-foot intervals. Actual sample intervals and corresponding depths are
shown on the boring logs. The barge mounted rig uses a manual hammer and the blows are of an N~o
en.ergy level.
Penetration test boreholes that met the Minnesota Department of Health (MDH) Environmental
Borehole criteria were sealed with an MDH-approved grout.
BRAUN
I NTE RTEC
City of Prior lake
Project BL-09-01027
May 4, 2009
Page 7
D.2. Material Classification and Testing
0.2.a. Visual and Manual Classification
The geologic materials encountered were visually and manually classified in accordance with ASTM Test
Method D 2488. A chart explaining the classification system is attached. Samples were sealed injars and
returned to our facility for review and storage.
. D.2.b. Laboratory Testing
The results of the laboratory tests performed on geologic material samples are noted on or follow the
appropriate attached exploration logs. The tests were performed in accordance with ASTM procedures.
D.3. Groundwater Measurements.
The drillers checked for groundwater as the penetration test borings were advanced, and again after
auger withdrawal. The boreholes were then backfilled as noted on the boring logs.
E. Qualifications
E.l. Variations in Subsurface Conditions
E.l.a. Material Strata
Our evaluation, analyses and recommendations were developed from a limited amount of site and
subsurface information. It is not standard engineering practice to retrieve material samples from
exploration locations continuously with depth, and therefore strata boundaries and thicknesses must be
inferred to some extent. Strata boundaries may also be gradual transitions, and can be ~xpected to vary
in depth, elevation and thickness away from the exploration locations.
Variations in subsurface conditions present between exploration locations may not be revealed until
additional exploration work is completed, or construction commences. If any such variations are
revealed, our recommendations should be re-evaluated. Such variations could increase construction
costs, and a contingency should b~ provided to accommodate them.
BRAUN
INTERTEC
City af Priar Lake
Praject Bl-Q9-01027
May 4, 2009
Page 8
E.l.b. Groundwater Levels
Graundwater measurements were made ,:,nder the conditians reparted herein and shown an the
explo.ration logs, and interpreted in the text af this repart. It should be nated that the observation period
was relatively short, and groundwater can be expected to. fluctuate in response to. rainfall, flooding,
irrigatian, seasanal freezing and thawing, surface drainage madificatians and ather seasanal and annual
factors.
E.2. Continuity of Professiona'. Responsibility
E.2.a, Plan Review
This report is based an a limited amaunt of information, and a number af assumptians were necessary to.
help us develap aur recommendations. It is recammended that aur firm review the geotechnical aspects
af the designs and specifications, and evaluate whether the design is as expected, if any design changes
have affected the validity af aur recammendations, and if our recommendatians have been carrectly
. interpreted and implemented in the designs and specifications.
E.2.b. Construction Observations and Testing
It is recommended that we be retained to. perform observatians and tests during canstruction. This will
aI/ow correlatian afthe subsurface conditians encountered during constructian with those enco.untered
by the borings, and provide continuity af professional responsibility.
E.3. Use of Report
This report is for the exclusive use of the parties to which it has been addressed. Without written
approval, we assume no. responsibility to. ather parties regarding this repo.rt. Our evaluation, analyses
and recommendatio.ns may not be appropriate for other parties or projects.
E.4. Standard of Care
In perfarming its services, Braun Intertec used that degree afcare and skill ordinarily exercised under
similar circumstances by reputable members af its professian currently practicing in the same lo.cality" No
warranty, express or implied~ is made.
BRAUN
. iNTE RTEC