WLA was tasked by the Papio-Missouri NRD to design the rehabilitation of the Mopac Trail between Fairview Road and Schram Road along Highway 50 in Sarpy County, Nebraska.  The existing limestone trail was plagued with drainage and erosion problems.  Approximately 5,500 feet of trail was regraded or elevated and then resurfaced with crushed limestone.  Shoulders and drainage channels were constructed in locations along the trail to facilitate and control storm water drainage.  Upon completion of the trail rehabilitation, disturbed areas were sodded and/or seeded and WLA ensured the establishment of the new vegetation.

WLA provided professional engineering services to Douglas County, in conjunction with Sarpy County and the Papio-Missouri NRD, for the analysis of the stabilization of Hell Creek.  Erosion and stream bank cutting are threatening bridges and other structures along the creek, as well as negatively impacting stream water quality.  WLA collected field data, conducted hydraulic and hydrologic modeling (HEC-RAS) and completed a sediment transport analysis using BEHI and Pebble Count data in order to identify and prioritize areas of concern.  Conceptual plans were developed, which included regrading of the existing channel and a combination of vegetative, bioengineering, and structural stabilization techniques.

In April 2007, the Village of Verdigre, Nebraska was faced with drastic changes to their wastewater treatment plant NPDES permit.  Along with these changes, all of the engineering planning that was completed to this point was not usable to address the changes in the treatment plant.  WLA was retained to develop a facility plan, complete final design to address the new permit limitations and provide assistance with regulatory and funding coordination.  New ammonia limits for year-round discharges were being proposed by the NDEQ that included a summer effluent limit of 0.64 mg/L, and limits for spring and winter.  In addition to ammonia, continuous disinfection of the effluent would be required.  The receiving stream, Verdigre Creek, is classified as a Class “A” stream, which is capable of supporting trout fish species.

WLA prepared the facility plan and proposed a treatment process that will meet all of the new effluent limitations.  The facility plan included significant upgrades to the existing mechanical wastewater treatment plant.  However, due to a series of challenges in available funding for an upgraded mechanical facility, further wastewater treatment alternatives were considered.  An updated facility plan was developed which evaluated several treatment options.  Alternatives evaluated included a packaged SBR mechanical plant, complete retention lagoons east and west of the village, modified controlled discharge lagoon, and a land treatment storage lagoon.  Capital cost estimates, operation and maintenance costs, replacement costs and life cycle costs were developed for each treatment alternative.  The Village decided to proceed with a complete retention lagoon west of Verdigre.  This option will address the pending NPDES permit by having no-effluent discharge to Verdigre Creek.  The complete retention lagoon also provided for greater funding assistance for the Village of Verdigre.

Project costs are estimated at $2,315,000.  Coordination with the NDEQ, Nebraska Department of Natural Resources, USDA Rural Development, and the Water/Wastewater Advisory Committee, WLA has successfully received approval for the facility plan and procured grant funding of $100,000 from the NDEQ Small Town Fund and $250,000 from the Community Block Development Program.  Additionally, the USDA Rural Development will fund the balance of the project in federal loans and grants.  WLA completed final design in December 2009 and it is expected that construction will be completed by the end of 2010.

WLA was retained by the Village of Shelby, Nebraska to coordinate regulatory approval with the Nebraska Department of Health and Human Services and to prepare design documents for the construction of a new municipal water supply well.  In the fall of 2005, Shelby’s primary water supply well showed significant signs of collapse and was pumping large amounts of sand.  With only one well in service and no standby wells, Shelby’s ability to provide emergency water services during high water demands would have been limited.  WLA proceeded to complete the necessary design drawings and specifications to procure regulatory approval and bids from drilling contractors.  The final project consisted of a 650 gallon per minute well with variable speed motor operation, well house and site work, and 800 feet of transmission main to the current treatment plant where the connection to the existing water system was made.

Biosolids from Lincoln’s Northeast Wastewater Treatment Facility (WWTF) are pumped to a location 1.5 miles north of the plant prior to land application.  The pipeline must pass below Interstate 80.  With the widening of the Interstate 80 corridor between Omaha and Lincoln, the relocation of this pipeline became a priority.  Based on the new Interstate design, the existing force main will no longer have sufficient cover.  In addition, the force main casing would not provide sufficient protection to span the entire width of the proposed six lanes of the interstate.  The depth of bury and span of the steel casing did not meet Nebraska Department of Roads (NDOR) minimum standards.  This deficiency required the City of Lincoln to reconstruct the undercrossing and WLA was tasked with the engineering design services.

During pre-design, a topographic survey, wetland delineation, and geotechnical soil investigation were completed.  Preliminary design consisted of pipe route selection, analysis of sludge pumping head conditions, material selection, and preparing an order of construction.  As analysis of the feasibility of horizontal directional drilling versus “jack and bore” installation methods was also completed.  The alignment and profile of the pipeline was coordinated and approved by the NDOR for the roadway undercrossing, as well as with the Nebraska Department of Environmental Quality (NDEQ) for required permitting.

The completed project will consist of approximately 425 linear feet of jack and bore underneath Interstate 80 of an 8″ diameter ductile iron pipe through a 20″ diameter steel carrier pipe, and connections to the existing force main.

When the new pipeline is constructed, the force main cannot be offline for more than 24 to 48 hours.  WLA prepared a detailed order of construction checklist to address the interruption.

WLA was contacted in December 2005 to assist with preparing design alternatives and completion of a Title 130 operating permit application for Maas Cattle Company in Stanton County, Nebraska.  This facility operates as a 10,000 head beef feeding facility and was faced with significant involvement and enforcement action from the EPA Region VII.  On an accelerated schedule, WLA successfully prepared engineering designs, permit application and required management plans to allow for timely regulatory review, approval and construction commencement within the 2006 construction season.

Sioux Falls, SD

The City was experiencing leakage in the original iron 60,000 cubic foot sphere piping system that carries digester gas to and from the sphere.  WLA was responsible for designing the new piping system,  constructed primarily from high-density polyethylene (HDPE). The new system uses all thermal fusion welded joints, which will hold gas to over 250 pounds per square inch (psi). The corrosion resistance and flexibility of the piping system will ensure a system capable of lasting for years. In addition, the HDPE system allowed the contractor to place the piping using either direction drilling or open cut methods, depending on which economy prove more cost-effective for a particular portion of the total length.

A Technical Memorandum was prepared that addressed various design issues and established requirements for this project. Working with a cover manufacturer, WLA prepared a cover system design that will cover the grit basin and meet City requirements. In addition to the cover system, an odor control unit was designed that generates a hydroxyl ion fog to oxidize hydrogen sulfide and eliminate related odors. A weatherproof enclosure was also designed to house the odor control unit and distribution piping of the fog to the grit basin. WLA prepared drawings and specifications that will be used to construct the cover system and other facility improvements.