The City of Delaware has good quality drinking water; however, the existing conventional treatment was not able to meet the new Long Term 2 Enhanced Surface Water Treatment Rule (LT2 ESWTR) and the Stage 2 Disinfectant/Disinfection By-products Rule (DBR) regarding Total Trihalomethanes (TTHMs) and Haloacetic Acids (HAA5). To meet these regulations, the team of CT and URS designed a 7.1 MGD water treatment plant with expansion capability to 13.0 MGD, consisting of both groundwater and surface water treatment systems, adjacent to the existing plant which will be used for pretreatment.
The WTP project design included:
- New ground water well
- Rehabilitation of two existing surface water intake screens and pump stations
- Modifications to rapid mix, flocculation and settling tank systems
- High rate pressure filters for ground water
- Ultrafiltration for surface water
- Nanofiltration for both ground and surface waters
- Chemical feed systems
- Backwash holding tank
- Membrane concentrate discharge system
- 1-million gallon clearwell
- High service pump station
- Standby power generator
- 21,000 sq. ft. process building
- Pre-engineered building over existing settling basins
The firm completed the engineering design for the chemical feed systems. This work included chemical analysis, jar testing, and determination of the preferred chemical coagulates. This resulted in the chemical feed system Design Summary shown in the table. From this information, CT engineers produced drawings and specifications for the WTP chemical feed systems.
Much effort went into the construction sequencing of the project in an effort to manage the capital expenditures and daily WTP operations.