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NLR Wastewater repairing, enhancing sewer system

The Levy and Lakewood areas of North Little Rock are currently the focus of major renovations of the city’s wastewater treatment infrastructure system.
The Levy and Lakewood areas of North Little Rock are currently the focus of major renovations of the city’s wastewater treatment infrastructure system.

Some North Little Rock city residents this year and in 2014 can expect to see some major infrastructure enhancements with the municipal wastewater treatment system.

The project started when the North Little Rock Wastewater Utility (NLRW) entered into a Consent Administrative Order with the Arkansas Department of Environmental Quality on Feb. 10, 2011 with the overall goal of eliminating sanitary sewer overflows (SSO), according to Marc Wilkins, general manager of NLRW. Sanitary sewer overflows occur when there is a blockage in the system or when an accumulation of leaks exceed the capacity of a pipeline.

“NLRW’s approach to accomplish this goal is to minimize the SSO’s due to a blockage through an aggressive cleaning and public education effort and to increase the capacity of the wastewater system with a selective Capital Improvements Plan,” Wilkins said.

In 2012, NLRW crews cleaned 1,192,468 lineal feet of gravity sewer pipelines which is about 43 percent of the entire gravity collection system. Cleaning improves the flow in the gravity sewer system by removing deposits of grease, roots, rags, sediment and debris. Large deposits of any of these items or a combination of any of these items can create a blockage which results in sewage overflowing from an upstream manhole or possibly backing up into a house or building through the private sewer service line. The majority of SSO’s in the NLRW gravity sewage system result from accumulations of grease, baby wipes or so-called “flushable wipes.” Public education helps individuals understand which items should not be put down the drain. NLRW distributes informational flyers with the monthly sewer bills three times per year. The Utility’s public education presentations have been focused toward 4th grade students in area schools but are available to any group or organization requesting information or a presentation, he said.

NLRW has secured a $21 million loan for capital improvements through the Revolving Loan Fund Program which is administered by the Arkansas Natural Resources Commission. Phase I of the capital improvements plan includes modifications to pump stations, treatment facilities and the collection system. Phase I includes 10 projects which were identified by staff as having the highest priority and which are designed to increase the hydraulic capacity of the sewage collection system and to reduce the amount of rainwater and groundwater entering the system, he said.

NLRW has contracted with RJN, Inc. of Dallas, TX to conduct a sewer system evaluation survey (SSES) of the collection system. A sewer system evaluation survey is a series of tests conducted in the field which are designed to locate defects which allow infiltration of rainwater or groundwater into the collection system. An accumulation of leaks can overload the pipelines resulting in an SSO.

The SSES fieldwork will include: manhole inspections, smoke testing, dyed water testing, closed-circuit televisions inspections, and flow monitoring. NLRW plans to conduct SSES fieldwork throughout the Utility’s service area over an 8 year period. The first 3 years of SSES fieldwork will be focused in the Levy (2012), Lakewood (2013) and Baring Cross(2014) areas. Rehabilitation of the collection system will follow the SSES fieldwork by about one year. The attached map identifies the 2013 focus area for SSES fieldwork.

Last year, NLRW conducted an SSES in the Levy basin. The recommendations of the 2012 SSES are being completed partly by NLRW personnel and partly with outside services. The NLRW has already completed 71 percent of the manhole repairs and 19 percent of the pipeline repairs recommended by the 2012 SSES. Outside services will be used to complete the sections of cured-in-place pipeline (CIPP) recommended in the SSES.

Cured-in-place pipeline is a rehabilitation method by which a resin impregnated sock is inserted into an existing pipe which is to be rehabilitated. Water is used to expand the sock so that it fits tightly within the host pipe. Heat is then applied to set off a chemical reaction which causes the resin to harden, thus forming a new pipe within the existing host pipe. Sewer services are reinstated using a closed circuit TV and a robotic cutter. The CIPP method of rehabilitation has the advantage of extending the life of the existing pipeline with minimal disruption to the ground surface.

NLRW opened bids for the 2013 CIPP Rehabilitation Project on Sept. 4. The project includes the installation of approximately 63,122 lineal feet of CIPP with internal service re-connects within pipelines ranging in size from 6- to 24-inch in diameter. The determination of pipeline segments to be rehabilitated resulted from SSES investigations in the Levy basin and from staff recommendations for pipelines in need of rehabilitation or beneath the water table in the Lakewood, NLR Academy, Campbell Road, Rose City Interceptor, Glenview and Fort Roots areas. The attached map identifies the project areas.

PM Construction & Rehabilitation of Pasadena, Texas, submitted the low bid in the amount of $2,355,644. The North Little Rock Waste Water Treatment Committee has authorized staff to award the contract pending receipt of authorization from the Arkansas Natural Resources Commission.

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