Red Bank Road Improvements for BCWS

BCWS – Red Bank Road Improvements
ACEC Engineering Excellence Awards – Category I: Special Projects
Red Bank Road Improvements
Category I: Special Projects
URS was retained by Berkeley County Water & Sanitation (BCWS) to develop a
roadway rehabilitation plan for approximately 750 LF of Red Bank Road (SC-29) near Goose
Creek that was experiencing severe subgrade fatigue and surface deflection. Historic inflow and
infiltration issues associated with an existing 36-inch reinforced concrete pipe (RCP) gravity
sewer piping system located beneath the water table and directly below the eastbound right-hand
lane of the 6-lane highway were causing settlement to the roadway above.
Our roadway engineers worked together with SCDOT, BCWS, the geotechnical team,
and our in-house water services personnel to establish viable alternatives for permanent subgrade
stabilization, each with varying degrees of cost and confidence. URS developed preliminary
designs and cost estimates for: 1) complete removal and rehabilitation of the 36-inch gravity
sewer line bedding; 2) partial subgrade excavation and rehabilitation using geotextiles; and 3)
zero-excavation soil improvement utilizing high-density polymer foam (HDPF) injections.
The project team selected zero-excavation HDPF rehabilitation as the safest and most
cost effective means of subgrade recovery due to the ability it gave the team to control risk and
budget over runs. URS worked with URETEK MA®, the turnkey HDPF design/installation
contractor, to develop a multi-depth injection plan to secure the soil and bedding materials
surrounding the gravity sewer line and the roadway subgrade above. The HDPF injections were
conducted nightly over a two-week period so that disruption to Red Bank Road traffic (>26,000
veh./day AADT) was avoided. Following completion of the rehabilitation work, URS worked
with the Berkeley County Engineering Department to include the milling and repaving of the
project area in the Berkeley County April, 2011 C-fund Road Resurfacing Project.
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BCWS – Red Bank Road Improvements
ACEC Engineering Excellence Awards – Category I: Special Projects
Project Background
The 36” reinforced concrete pipe (RCP) gravity sewer line at the root of this project was
constructed in 1980 as part of the Lower Berkeley County Wastewater Interceptor System. This
section of line was located just within the 100’ right-of-way of Red Bank Road (S.C. Highway
29), which at the time was a two-lane highway. In 1984, the SCDOT widened Red Bank Road
to a seven-lane section, which consumed the majority of the remaining right-of-way, including
the real estate directly above the 36” RCP sewer line.
In 2002, Berkeley County Water & Sanitation (BCWS) performed a slip-lining project to
mitigate inflow and infiltration problems associated with the aging and decayed reinforced
concrete pipe, which is not uncommon for materials subject to similar conditions at twenty years
of age.
While this “inside-out” solution was effective in sealing the BCWS system from
intruding groundwater, the damage to the pipe bedding and surrounding soils caused by twenty
years of fine particle washing and raveling remained. By 2010, continued degradation of the
earth materials surrounding the pipe and eventually the roadway’s sub-base materials had
resulted in multiple, severe asphalt failure points, creating an unsafe riding condition and
requiring the constant attention of BCWS line
crews to perform lane closures and patching
operations.
At that time, BCWS procured
URS to determine a safe, cost effective, and
permanent solution to repair the deficiencies,
stabilize the road base, and stop the unending
cycle of surficial repairs.
Roadway Patching
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BCWS – Red Bank Road Improvements
ACEC Engineering Excellence Awards – Category I: Special Projects
Role of Entrant’s Firm in the Project
URS’s services included performing required surveys, preparing preliminary designs and
cost estimates for three (3) alternative solutions, and preparing the final design and permitting for
the most favorable solution. URS also assisted with project start-up, quality assurance, and
validation of results for the High-Density Polymer Foam (HDPF) installation, as well as the
preparation of construction documents and specifications for the final phase of the project, which
was the milling and resurfacing of the project area.
Role of Other Consultants Participating in Project
S&ME performed the initial Geotechnical Exploration and Report for the project, and
were also instrumental through the process of developing alternatives. URETEK MA® provided
turnkey design and installation services, including development of the HDPF injection grid and
selecting the appropriate formula for the material.
Description of the Entrant’s Contribution to the Project
Original or Innovative Application of New or Existing Techniques
The initial and most conventional repair method evaluated by URS was to open-cut Red
Bank Road, completely expose the 36” reinforced concrete pipe (RCP) and its surrounding
bedding material, and perform a rehabilitation of the fill material in manageable phases. While
this approach provided the greatest degree of certainty by allowing a complete underground
inspection and replacement of the bedding, it also posed the greatest safety hazard to the
traveling public and the construction workers by creating a vast and potentially unstable
excavation in the middle of a high-volume (26,000 vehicles/day) thoroughfare. Shoring and
dewatering were two significant cost items that were difficult if not impossible to accurately
determine.
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BCWS – Red Bank Road Improvements
ACEC Engineering Excellence Awards – Category I: Special Projects
The second alternative, a partial excavation with repairs made only above an intermediate
depth, did not provide the certainty of fixing the root problem and still required excavation
activity in the roadway with the potential of exposing irreparable “soft spots” at unknown
locations.
The third and ultimately most suitable approach was a zero-excavation method that,
properly installed and monitored, would ensure complete subgrade remediation without touching
the claw of an excavator to the pavement.
This highly
innovative solution employed a complex, three-dimensional
grid of HDPF injections along the entire “problem area” of
the 36” host pipe. Once injected at calculated depths, the
chemical components react to compress, strengthen, and
occupy voids in the degraded earth materials, providing an
“outside-in” fix to recover bearing capacity and prevent
Schematic
further raveling and subsidence.
Future Value to the Engineering Profession
The greatest value realized by this project was the elimination of public safety hazards
and unknown cost variables that accompanied traditional repair methods. Numerous risk factors,
including high groundwater elevations, damage to other critical utilities in the work area, and
prolonged highway closures could have easily driven the cost and schedule of an openexcavation project beyond the feasibility of completion; or worse, compromised the safety of the
traveling public.
The zero-excavation, HDPF solution allowed the seven-lane highway to be
returned to full service at the end of each night-time work period and allowed the Owner and the
Engineer to maintain control of the project. We hope for ourselves and others to have future
opportunities to implement this method as a viable alternative to traditional utility repair means.
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BCWS – Red Bank Road Improvements
ACEC Engineering Excellence Awards – Category I: Special Projects
Social, Economic, and Sustainable Design Considerations
URS, BCWS, and SCDOT approached this project with the safety of the public as the
paramount objective. Eliminating the need for unpredictable excavations in extreme traffic
conditions was the instrumental to upholding this goal, as well as controlling contingency costs;
which in similar conditions are all too often discovered after ground is broken. This solution
also kept the waste generated by the project to nearly net-zero, whereas other methods would
have required the hauling and disposal of thousands of cubic yards of unsuitable materials.
Complexity
The implementation of such an innovative technology required open minds and sharp
pencils for all parties involved. Knowledge of the conditions within the actual problem areas
(closest to the host pipe) was limited by the team’s physical ability to collect core samples
without potentially compromising line’s integrity, which presented a most formidable challenge.
The project team surmounted this obstacle by installing a “test patch” of HDPF foam at the head
of the project area. By measuring the amount of material accepted through precision injections,
URETEK MA® was able to accurately gauge and budget for the quantity of material required for
the remainder of the project. In-place density was recorded before and after the injections using
a Dynamic Cone Penetrometer (DCP) rig in order to ensure that the product would react properly
and provide the needed increase in the stiffness of the soils supporting the roadway.
Material installation quantities and before-and-after
DCP results were monitored nightly throughout the project; and
using this information, URS was able to correlate the amount of
HDPF accepted to the change in the in-place density to ensure
satisfactory results were being achieved.
Dynamic Cone Penetrometer Testing
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BCWS – Red Bank Road Improvements
ACEC Engineering Excellence Awards – Category I: Special Projects
Exceeding Client/Owner Needs
From project inception to the final as-built
road surface survey, URS worked closely with the
BCWS Engineering Department and their line
crews, who themselves contributed a great amount
to the success of this project and deserve
Injection Work Area
recognition as a key player. The value of a project
of this nature is measured not only by the tangible metrics such as cost and schedule, but also by
the sense of accomplishment felt on all accounts after completing an “outside the box” concept
and taking that experience forward. The project was completed well within its $250,000 budget
at approximately $200,000; and was completed three months in advance of the scheduled date of
December 13, 2011. More importantly, the time required for actual construction was confined to
only three (3) weeks and Red Bank Road never saw a peak traffic hour of lane closure.
The final roadway resurfacing phase of the
project provided an added value to the client by
allowing the work to be grouped with a Berkeley
County C-Funds resurfacing project, which provided
them with a better bulk material price and saved on
traffic
control
and
redundant
pre-construction
Final Roadway Surface
proceedings.
“We thank URS for assisting us with an innovative design that saved time, money, and public
disruption. All accomplished while providing a very solid end result!”
Chad M. Abrams, E.I.T, BCWS
BCWS – Red Bank Road Improvements
ACEC Engineering Excellence Awards – Category I: Special Projects
Key Participants
Owner: Berkeley County Water & Sanitation
212 Oakley Plantation Drive
Moncks Corner, SC 29461
Contacts:
Mr. Micah G. Miley, P.E., Director of Engineering
(843) 719-2679
[email protected]
Mr. Chad M. Abrams, E.I.T., Engineer
(843) 719-2319
[email protected]
www.bcwsa.com
Engineer: URS
101 Research Drive
Columbia, SC 29203
Contacts:
Mr. John W. Culbreath, P.E., Urban Development Section Leader
(803) 254-4400
[email protected]
Mr. Adam C. Way P.E., Project Manager
(803) 254-4400
[email protected]
www.urs.com
Subconsultant (Geotechnical): S&ME, Inc.
620 Wando Park Boulevard
Mt. Pleasant, SC 29464
Contact: Mr. Michael S. Ulmer P.E., Senior Engineer
(843) 884-0005
[email protected]
www.smeinc.com
BCWS – Red Bank Road Improvements
ACEC Engineering Excellence Awards – Category I: Special Projects
Contractor: URETEK MA®
4840 Forest Dr.
Columbia, SC 29206
Contact: Mr. Bryan Honeycutt, Regional Manager
(803) 318-2225
[email protected]
www.uretekma.com
Photo 1: Multiple pavement patches above weakened pipe bedding and road sub-base.
Photo 2: Concentrated problem areas required redundant pavement patching operations, meaning continued road closures and
endless maintenance costs.
Photo 3: Positive pressure created by HDPF injections exposed
weak points in the existing asphalt surface. Surface flaws repaired with final road resurfacing phase of the project.
Photo 4: HDPF externally seals voids in sanitary structures at
varying depths.
Photo 5: View of work area with dual injection tubes for HDPF
coverage at varying depths.
Photo 6: Project profile indicates relative depth of subsurface utilities and water table.
BCWS – Red Bank Road Improvements
ACEC Engineering Excellence Awards
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PRESS RELEASE - FOR IMMEDIATE RELEASE
For More Information, contact:
Mr. Adam C. Way, P.E.
URS
101 Research Drive
Columbia, SC 29203
803-254-4400
[email protected]
URS Completes Red Bank Road Improvements for BCWS
COLUMBIA, S.C. – URS Corporation (URS) was retained by Berkeley County Water &
Sanitation (BCWS) to develop a roadway rehabilitation plan for approximately 750 linear feet
(LF) of Red Bank Road (SC-29) near N. Rhett Avenue in Goose Creek, South Carolina, which
was experiencing severe subgrade fatigue and surface deflection. Historic inflow and infiltration
problems linked to an aging 36-inch reinforced concrete
The reinforced concrete pipe (RCP) gravity sewer piping system, located beneath the
water table and directly below the eastbound right-hand lane of the seven-lane highway, were
causing subgrade raveling and subsidence to the roadway above. Internal repairs made to this
line in 2007 repaired the sewer system, but damage done to the earth surrounding the host pipe
remained. Ongoing lane closures and crew costs to perform surficial maintenance on this major
highway (>26,000 veh./day) prompted BCWS to investigate a safe, cost effective, and permanent
solution to repair the deficiencies, stabilize the road base, and stop the unending repair cycle.
URS’s roadway engineers worked together with SCDOT, BCWS, the geotechnical
engineering team, and our in-house water services personnel to establish viable alternatives for
permanent subgrade stabilization, each with varying degrees of cost and confidence. URS
developed preliminary designs and cost estimates for: 1) Complete removal and replacement of
the 36-inch gravity sewer line’s bedding material; 2) partial subgrade excavation and
rehabilitation using geotextiles; and 3) zero-excavation soil improvement utilizing high-density
polymer foam (HDPF).
The project team selected the zero-excavation HDPF rehabilitation as the safest and most
cost effective means of subgrade recovery. URS worked with URETEK MA®, the turnkey
HDPF design/installation contractor, to develop a complex, three-dimensional grid of HDPF
injections along the entire “problem area” of the 36” host pipe. Once injected at calculated
depths, the chemical components react to compress, strengthen, and occupy voids in the
degraded earth materials, providing an “outside-in” fix to recover bearing capacity and prevent
further subsidence. The HDPF injections were conducted nightly over a two-week period so that
Red Bank Road traffic would not be disrupted.
URETEK’s patented HDPF polymers have a chemical composition that allow for direct
application into water or saturated environments. The polymer is inert and non-toxic; and its
monolithic nature ensures that the material will not be subject to underground water erosion or
weakening while its high density composition provides ample physical strength characteristics to
maintain structural support of even the heaviest foundations.
Following completion of the subgrade rehabilitation work, URS worked with the
Berkeley County Engineering Department to include the milling and repaving of the project area
in the Berkeley County April, 2011 Road Resurfacing Project (C-fund Project No. 09 B 004),
saving BCWS time and financial resources.
URS is one of the nation’s leading providers of engineering, construction and technical
services in the infrastructure, federal, power, and industrial and commercial markets.
Engineering News-Record (ENR) magazine annually ranks URS among the top engineering
firms for design services. URS has ranked in the top three of ENR’s list for more than a decade
and is highly ranked on a number of specialty lists.