PROJECT OVERVIEW

NBU’s North Kuehler WWWTP (3.1 MGD) had not undergone any rehabilitation or improvements since it was built in 1985 and NBU’s South Kuehler WWTP (4.2 MGD) had not undergone any rehabilitation or improvements since 1991. Both facilities were in need of significant rehabilitation, replacement of major equipment, and a mass treatment expansion of their process basins and sludge handling facilities. Both WWTPs were organically overloaded as they were originally designed for 150-mg/L BOD5 and 160-mg/L BOD5 respectively, yet the influent BOD5 was approaching 300-mg/L, and the original design did not include a nitrification process.

NBU received a TP limit in the 2010 TPDES permit renewal that included a 12-month compliance schedule. To comply with their TPDES requirements, and make timely progress, our team worked with NBU on a plan with 3-bid packages.

SERVICE DETAILS

Phase I consisted of NBU’s top priority of complying with its newly issued TP limit. Given the short time frame, a chemical phosphorous removal system was selected. Within a 12-month time frame, Quiddity completed a phosphorous reduction plan, submitted it to TCEQ for approval, and executed an expedited design in order to leave adequate time to complete construction. During the construction of Phase I, the design of Phase II commenced which consisted of constructing a new solids handling facility to increase the dewatering capabilities to enable NBU to process the increased sludge produced from the chemical phosphorous removal system in addition to the excess sludge from the higher influent BOD5.

Phase II consisted of a new 7.3-MGD belt press dewatering facility, expandable to 20-MGD, a new polymer building, a control building, and sludge pump modifications. During construction of Phase II, Phase III commenced which consisted of expanding the existing mass treatment capabilities through construction of an equivalent of 3.5-MGD aeration basins, installation of submerged membranes within the existing aerobic digesters for sludge thickening, existing process, and digester blower replacements with new PD blowers with a VFDs and a DO control system; replacement of existing MCCs, replacement of portions of existing aeration equipment, sludge pumps, drain return pumps, expansion of the existing fiber communication network, and associated SCADA upgrades.

Construction of Phase III was very complex in terms of sequencing and maintaining adequate treatment of existing flows during construction. Every existing treatment unit was taken out of service at various points in time to allow for the upgrades (4-independent trains without common flow split between each process). As a result of the necessary sequencing, construction took 3-years to complete.

Construction Cost

Phase I – $345,934   |   Phase II – $3,556,898   |   Phase III – $14,492,103