Wastewater collection system In the 1800s wastewater management consisted of releasing untreated wastewater directly into the Trinity River. In 1913 the
Texas legislature passed an anti-pollution law that directed all cities with populations greater than 50,000 to cease discharging untreated wastewater into streams. In January 1917 Dallas completed a per day wastewater treatment plant, the Central WWTP, to comply with this law. The plant was expanded to keep up with Dallas’ growth in the 1920s. Service was expanded to Highland Park and University Park in the 1930s. In 1964 the Central WWTP was augmented with a per day Southside Oxidation Pond Facility (now called the Southside WWTP). For convenience in managing the city's extensive network of interceptor and collector sewers, DWU has divided the system into a number of primary sewer basins based on the drainage pattern for the sewers within the basin. There are 12 primary basins. Ten of the basins transport flow to Dallas treatment plants. These basins are (alphabetically) the Elam Creek, East Bank, Five Mile Creek, Hickory Creek, Prairie Creek, South Dallas, Warren Avenue, West Bank and White Rock Creek Basins. Each basin is named for, and discharges flow into, the major interceptor sewer line traversing the area. The other two primary basins transport flow to other regional sewer providers. These basins, the TRA and Garland basins, are named after the regional provider. The primary basins are further divided into smaller drainage basins, termed sewersheds. 48 of the sewersheds are tributary to Dallas wastewater treatment plants, three of the sewersheds are tributary to the
Trinity River Authority (TRA) system, and one is tributary to the Garland system. The DWU Wastewater Collection System is over long and includes 15 lift stations. Pipe sizes in the system range from 4" to 120" inches. DWU's wastewater collection program is primarily responsible for the pipes built outside the plant footprints. Key activities of this program include: • Sewer line maintenance (root control, mechanical cleaning, high velocity pressure cleaning, rehabilitation, repair, and point repairs) • Emergency response • Television inspection • Flow monitoring
Wastewater treatment The city operates two wastewater
sewage treatment plants, Central and Southside. The
Central Wastewater Treatment Plant (CWWTP) has a design treatment capacity of per day, and treats an average flow of about 100 MGD. The peak treatment capacity of CWWTP is rated at per day. City of Dallas's Central Wastewater Treatment Plant (CWWTP) is a conventional activated sludge plant with trickling filters. DWU Central WWTP is in operation for more than 100 years and has gone through various changes throughout those years. Most prominently, after the introduction of Clean Water Act, activated sludge was included to the treatment process along with trickling filters. DWU Central plant is divided in to three major sections: Dallas plant, White Rock plant, and Activated Sludge Plant. Wastewater flows from various sections of the City come through Cadiz pump station or via White Rock interceptors to both Dallas plant and White Rock plant. After the primary treatment (including bar screens, primary clarifications and trickling filters) at both of these plants, the flow is combined at Activated Sludge Influent Pump Station (ASIPS) which is then diverted to Complex A and Complex B for activated sludge process. Effluent of activated sludge process passes through secondary clarification and then disinfected using gaseous chlorine in chlorine contact chambers. After disinfection, effluent is filtered through dual-media gravity filters and de-chlorinated before discharging into the Trinity River. DWU Central plant pumps its sludge to DWU Southside wastewater treatment plant for the anaerobic digestion. DWU Central plant provides Type II reuse water to a city park and two city-owned golf courses. The reuse water has residual chlorine per requirement. DWU Central Plant currently has six (6) “A”, seven (7)”B”, 14 “C”, and five (5) “D”
Texas Commission on Environmental Quality TCEQ Certified operators on staff. CWWTP is ISO 9001, 14001, and 18000 compliant. CWWTP maintenance staff has implemented predictive maintenance program (PdM), Lean Six Sigma as well as utilized drone technologies to manage assets while reducing risks. Awards Received by DWU's Central Wastewater Treatment Plant (CWWTP): • WEAT Plant of the year award for Year 2016 (State) • WEAT Operator of the Year Award (State) • WEAT George Burke Safety Award (State) • WEF Water Heroes Award (National) CWWTP was also nominated for the Resilient Utility of the Year Award for year 2017. The Southside Wastewater Treatment Plant (SWWTP) has a maximum capacity of 160 MGD and treats an average flow of about 65 MGD. Both CWWTP and SSWWTP are permitted by the
Texas Commission on Environmental Quality to discharge to the
Trinity River.
Pretreatment and Laboratory Services Pretreatment and Laboratory Services (PALS) administers local, state, and federal regulations to control pollutants discharged from commercial and industrial users (IUs) within the city of Dallas which may pass through or interfere with the city's Publicly Owned Treatment Works (POTW). The city's POTW consists of two wastewater treatment plants treating up to per day, fourteen pump stations, and over of sanitary sewer collection pipelines. The Pretreatment Program administers and enforces the regulations in order to: • Protect the city's wastewater collection systems, treatment plants, and workers • Allow the beneficial re-use of bio-solids • Allow the reclamation of treated effluent for irrigation and other uses • Maintain water quality in the Trinity River. POTWs are designed to treat typical household wastes and biodegradable commercial and industrial wastes. Commercial and industrial facilities that discharge toxic pollutants to the treatment plants may be very detrimental to treatment plant processes and the environment. IUs which discharge pollutants into the POTW are required to install, operate, and adequately maintain pretreatment equipment to remove pollutants that could otherwise damage, obstruct, interfere with, or pass through the POTW. Examples of such pollutants include heavy metals, cyanides, toxic organics, and acidic or basic wastes from industrial operations. Heavy metals and some organic chemicals which cannot be treated by the biological treatment process can threaten the bacteria which are necessary to the treatment process at the wastewater treatment plants. Wastewater from restaurants and other food service industries are often more problematic due to the prevalence of conventional pollutants such as grease, organic matter and solids. Grease can clog and overload the sewer system. Processing these food contaminants raises the cost of treating wastewater. The Pretreatment Program protects the treatment process and keeps costs down by working with local businesses to minimize pollutant discharges. Activities of the city's Pretreatment Program include the review of pretreatment designs, the issuance of permits, facility inspections, monitoring of facilities (wastewater sample collection), review of industry self-monitoring reports, and enforcement activities. PALS also operates 2 Process Laboratories, one for each of the two wastewater treatment plants, and an Analytical Laboratory, whose primary function is the analysis of industrial wastes discharged to the collection system. ==Capital improvement operations==