Filter Backwash Waste Treatment. System (including pump station). URS will design up to a 2 mgd package treatment system to take filter backwash waste and treat it to a maximum of 2 NTU for return to the head of the plant for reuse. The package plant would be an above-grade, steel package plant on a concrete slab and have a maximum return rate to the head of the plant be 10%, at any given time, in accordance with the DPH guidelines. URS will also design a steel above grade backwash waste storage tank to enable the return of potentially all of the filter backwash waste to the head of the plant. As part of this item, the existing filter washwater pumps will be replaced as necessary with properly designed pumps coordinated with the washwater treatment plant. In lieu of the steel backwash waste storage tank, URS will design a new in ground basin(s), or modifications to the existing basin, capable of meeting the storage and pumping capacity needs of the plant. Selection between the steel backwash tank vs. ground basin will be made by City, with a URS recommendation and input, during preliminary design.
