The Las Vegas casino resort area is a popular destination for tourists and many visitors to Las Vegas experience congested traffic conditions between the McCarran Airport and the Las Vegas “Strip” area and along busy Las Vegas Boulevard, regardless of the hour of day or night.
Combined with traffic delays and detours due to the recent rehabilitation work and 24-hour bypass pumping, you might envision a public relations nightmare. Rehabilitation work for the Clark County Water Reclamation District’s Phase 1 Pipeline Rehabilitation was conducted to minimize impacts to the public and the casino resorts. Public relations coordination was a critical activity that occurred throughout the project.
The District initiated the project in reaction to a failed concrete sewer pipe that occurred directly behind the Treasure Island Casino Resort. In response, the District initiated the procurement of design services from HDR Engineering Inc. on one of two projects that addressed suspected corroding concrete pipe and manholes.
Scope of Work
This rehabilitation project provided for the rehabilitation of approximately seven miles of existing sewer pipelines and about 117 associated manholes at locations within the Clark County Water Reclamation District’s system. Rehabilitation methods included cured-in-place pipe (CIPP) and cured-in-place manhole (CIPM) liners for existing 18- to 36-in. diameter, reinforced concrete pipe beneath Tropicana Avenue and Flamingo Road and associated manholes. Additional rehabilitation techniques included in the project were NeoPoxy liner end sealing and connection sealing and Top Hat connection liners.
Las Vegas Paving was the successful general contractor and Insituform supplied and installed the CIPP for pipes. PolyTriplex supplied and installed the CIPM in manholes.
The project route is located along roads within the casino resort area of Las Vegas, characterized by high traffic volumes and directly adjacent to large casino resorts. Bypass pumping of the flows had to be installed 24-hours a day and proved to be one of the biggest challenges on the project. Construction was completed primarily at night due to the high traffic volumes and daytime temperatures (in excess of 115 F on some days).
Because of the public relations outreach effort by county officials prior to and during construction and the contractor’s face-to-face coordination with resort owners during construction and extensive traffic controls, this project proceeded according to schedule.
The project was implemented in partnership with public agencies, contractor, design consultants and the owner. Permit requirments included the Nevada Department of Transportation (NDOT), FAA and the Clark County Public Works Department.
Rehabilitation construction occurred during the hot, summer months in 2005, which provided another major challenge to the installation and curing of the CIPP and CIPM products. Insituform set up a wet-out facility at the owner’s treatment plant site to facilitate a faster delivery time for the product to the site.
The district responded to a system failure in the casino resort area by proceeding immediately to design assuming the pipes were in poor condition. This resulted in design conditions for a worst-case scenario. Later, condition assessment work in Phase II validated this decisionas pipes again were found to be in poor condition. Design parameters used included fully deteriorated, 5 percent ovality, 2 safety factor and a soil modulus (E’) of 700 psi. This resulted in a liner pipe with thicknesses that ranged from 1/4 to 1 in.
Polyester resin was used for this sanitary sewer application. The design of the CIPP recognized the non-uniform cross section and bifurcation present at the spring line of the pipe. Where necessary, the contractor was required to account for the bifurcation condition by applying a structural repair prior to lining. No additional repairs were required and the liner was successfully installed in the pipes.
Neopoxy End Seal & Connection Sealing
Neopoxy sealing was used on pipes greater than 18 in. in diameter to seal end points and connections of the liner. The applicator system carries the mixed epoxy resin into the host pipe. Once in the host pipe and facing the lateral connection, the epoxy material is applied uniformly on the exposed edges and at the base of the lateral connection. Using the edge of the trowel (1/16-in. thick), the material is pushed into the annular space, along the circumference of the lateral cut as much as the annular space will accept. The degree of acceptance is more on the order of 2 ft rather than 6 in. The material is forced into the annular space and fills irregular surfaces at the lateral connection to ensure water tightness.
Top Hat Connection Liner
Southwest Pipeline and Trenchless Corp.’s Top Hat System is a specialty liner designed to seal connections on lined pipe less than 24 in. in diameter. This liner is installed using equipment that inflates and pushes the liner into the connection, leaving a 2- to 3-in. brim in the main pipe and cures in about 10 minutes. This provides a watertight seal at the connection.
CIPM Liner Installation
CIPM manhole liners were sized individually for the structures in this project, as there were a variety of manhole shapes and sizes. Consideration of stretch during installation and shrinkage while curing and aging was required for liner sizing. Liner thickness was based on the three depth categories provided by the manufacturer that resulted in a CIPM liner thickness design of 0.125 to 0.175 in. Depths varied from 6.3 to 27.5 ft. Test property values were designed for ASTM D790, D695, D638, and D2240.
Construction Challenges and Successes
A number of issues were addressed during design that impacted the overall budget and schedule of the project. Bypass pumping was particularly challenging due to high traffic volumes in the Resort Corridor. Flows ranged from 4 to 8 million gal per day in the line scheduled for rehabilitation. Smaller-diameter pipes were available nearby for bypassing, but could not accommodate most of the flows in the mainline. The contractor had to bury all of the bypass pipes within the roadways, and traffic controls were setup 24 hours a day, seven days a week.
This leads to the next major item that was addressed during construction — community relations. The contractor coordinated with specific property owners for bypass requirements and access coordination. A community relations specialty firm was hired by the District to provide public announcements each week as to the specific location of work.
According to Dick Anderson, district resident inspector during construction, the major challenge was coordinating the CIPP inversions and traffic control with the casino operations staff. The casinos had more to say about the project schedule due to their upcoming events than most of the agencies in the area.
Another major challenge was coordination with the local office of NDOT, which had conflicting work along the same alignment and paved over the manholes prior to final acceptance of approximately 25 percent of the rehabilitation work. This was also a problem during design of the project when NDOT paved over another road that precluded flow monitoring and resulted in a change order due to a significant increase in anticipated flows.
Another problem arose, resulting from the lack of prior inspection work because additional connections to the sewers resulted in delays due to changes needed in the bypass plans. Traffic control in the area was extremely challenging, but was handled professionally thanks to cooperation from local traffic permitting agencies.
Richard Anthony with PolyTriplex says that many of the challenges and issues related to the manhole lining were addressed early on in construction, prior to sending crews into the field. Weekly construction meetings provided a way for management and field supervisors to raise issues and explore resolutions. Traffic and weather were the primary challenges in the field, according to Anthony. The traffic is fast and in high volumes, and drivers are aggressive at all hours of the day and night. Traffic control measures were taken seriously. The weather could not be managed so easily. Summer construction saw daytime temperatures as high as 117 F and caused premature curing of manhole liner products. Nighttime temperatures were still above 100 F at 2 a.m. The second phase of manhole lining work occurred later in the project when temperatures were reduced to 80 to 90 F.
Project successes included successful completion of all but two CIPP inversions. No major delays occurred due to installation of the pipe liner due to effective communication between the owner and the contractor. Anderson felt that the design engineers were responsive on submittal turnarounds, which contributed to the smooth operation of the project. The entire team of contractor, owner, consultant and subcontractors worked diligently to make the project a success.
Allison Ratliff is a project manager with HDR Inc.., which is based in Omaha, Neb.