Regional Treatment Plant Hydraulic Improvements

Grand Prairie, Texas

Perkins Engineering Consultants, Inc., serving as a subconsultant to another firm, was responsible for identifying hydraulic relief improvements needed to enable this 152-mgd regional plant to better distribute flows from its 12 secondary clarifiers to its 32 low-head effluent filters, some of which are being abandoned while others are receiving significant capacity upgrades via cloth media retrofits. Two relief tunnels were identified and designed. The first involved a relatively short but complex 84-inch relief tunnel to connect the effluent troughs from two isolated banks of clarifiers. This pipeline was partially installed by open cut, but due to electrical duct banks and other large utilities in the vicinity, specific portions had to be installed by tunneling in tight, confined operating plant areas and beneath roadways. This project was completed in 2016. A second cast-in-place relief tunnel is scheduled for construction in 2017.

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Regional Wastewater Systems Evaluations

Wylie, Texas

When additional customer cities are added to a regional wastewater facility, or when the choice is between a plant expansion or resurrecting a mothballed WWTP, determining the best course of action can be daunting.  We recently helped one client with this decision at two separate regional systems.  In both cases, we coordinated flow and rainfall monitoring and associated inflow/infiltration analysis, Q vs. i analysis and development of future storm and flow projection scenarios.  Population and flow projections were considered as was the cost of returning old facilities to service. At one facility the Owner decided to expand an existing facility from 1.5 MGD to 3.0 MGD; PECI designed the plant expansion.  In another, PECI conducted a subsequent study evaluating adding two new customers in the regional system.

Truck Weigh Scale Evaluation

In working with solid waste management staff and wastewater plant operations staff, PECI evaluated on-site weighing options at several wastewater treatment plants to assist our client with maintaining compliance with local, state and federal transportation rules.   Reviewing container loading and hauling operations, analyzing sludge processing data, and current documentation, PECI evaluated various weighing options including portable scales, steel deck scales, low speed weighing scales, electronic or hydraulic load cells on the existing container systems, and overhauling the existing sludge conveying and receiving equipment with a new silo discharge system. Conceptual layouts and preliminary costs were developed for each of the options presented.  In addition, modifications to operational procedures were included that could be performed without capital expenditures to maintain compliance with transportation rules.

Nutrient Removal Evaluation

Sherman, Texas

PECI identified and evaluated nutrient removal process configurations for a 16 MGD municipal wastewater treatment plant.  Unit processes, configurations and preliminary costs were determined for chemical phosphorous removal and biological nutrient removal (BNR) processes.  Three alternatives for BNR were evaluated as part of the project.  Capital and operating costs for one alternative for BNR, Anaerobic/Anoxic/Aerobic, along with upgrading the aeration system, chemical phosphorous removal and side stream treatment of the supernatant stream from solids handling were also determined.

Operation and Maintenance Manuals

Perkins Engineering Consultants, Inc. has worked with operations and maintenance staffs at wastewater treatment plants up to 33 MGD to develop plant-wide operation and maintenance manuals to satisfy the requirements of TCEQ and EPA.   Reviewing and cataloging numerous vendor manuals, plans and drawings, PECI created an electronic library of documents, consolidating the information of the current plant configuration into the O&M manual, and providing links in the manual to the newly-established electronic library.   Each step of the treatment process is documented and accompanied with a process flow diagram to quickly see how flow enters and exits a treatment process.  Valves, gates and equipment are also shown, and tagging to match the client’s asset tracking is included.  The manuals also included discussion on overall plant safety, incoming power and distribution, emergency operation and training.  These manuals typically include a comprehensive update of the plant’s schematics, incorporating equipment that has changed since original construction.

Compost Bagging Facility

Melissa, Texas

PECI to designed fabric storage structures for the NTMWD 121 Regional Disposal Facility to house compost bagging equipment. The project included two pony wall fabric shelters. Both shelters were supported by 6 foot stack (3 high) of Lattimore blocks and included interior lighting and other electrical for miscellaneous power needs.

The project also included concrete floors for both shelters, a concrete driveway for forklift operation between pony wall shelters and a concrete parking lot at the administration building. A compost storage facility was constructed as part of the project using Lattimore blocks.

Vehicle Washing Facility for Biosolids Transport Trucks

Melissa, Texas

PECI designed a trailer washing facility to clean emptied biosolids trailers at a regional disposal facility. PECI evaluatde possible options and develop cost estimates for the following two key facets of design:

  1. Truck wash location; and
  2. Water clarity and disposal.

Four truck wash locations were evaluated. Options for increasing water clarity included chemical coagulation, electro-coagulation and water softening. The NTMWD 121 Regional Disposal Facility is not served by an existing sewerage system and recycle of flows was considered. Construction of the truck wash and associated facilities was completed in 2011.

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Snail Collection basin and Slurry Pumping System

Garland, Texas

As part of a larger plant rehabilitation project, PECI designed a special settling basin to capture snails from a trickling filter process. A pumping system was designed to move the snail-laden slurry into a classifier so that snails could be deposited in a roll-off container for hauling off-site.

Dewatered Snails

Dewatered Snails Collected for Disposal

Collection System Meter Stations

Perkins Engineering Consultants has become a leader in meter station evaluation and design for wastewater collection systems.  From traditional measuring devices, such as Parshall and Palmer-Bowlus Flumes, to cutting edge technology, such as the Hach Flodar® AV sensor, our engineers have evaluated and designed multiple meter stations.  Flow regimes, hydraulic calculations and interpretation of the results all play important roles in the success and accuracy of any meter station.  Our expertise extends to evaluating upstream and downstream conditions, determining the state of flow across the entire range of flows, and setting the appropriate installation conditions for successful operation.