Milwaukee Metropolitan Sewerage District Conveyance and Treatment System MACRO made available by Eric Loucks,, CDM
MMSD Collection System Operations MMSD operates an extensive system of sanitary sewers to collect, convey, and store wastewater originated by local sewer systems. Local systems are operated and maintained by municipalities within the District and those contracted with MMSD. Wastewater flows to the local systems, is collected by the District's intercepting system, and then conveyed to MMSD's two wastewater treatment plants.
Main Components of System Metropolitan Interceptor Sewer (MIS) System Inline Storage System (Deep Tunnels) Central Control System
Metropolitan Interceptor Sewer (MIS) System A network of sanitary sewers that intercept wastewater from local sanitary and combined sewer systems within service area. Divided into seven subsystems for purposes of flow monitoring analysis and system control. Flows can be diverted between the subsystems for conveyance to either the Jones Island or South Shore treatment facilities, or to the District's Inline Storage System (Deep Tunnels), where they can be stored until the plants have available capacity for treatment.
Inline Storage System (Deep Tunnels) Consists of 19.4 miles of tunnels 300 feet below ground that temporarily stores peak wastewater flows that exceed treatment plant or MIS capacities. Can hold up to 405 million gallons of flow and was designed to eliminate overflows from the separated sewer area and to greatly reduce overflows in the combined sewer area. Became fully operational in 1994 and has substantially reduced the number of annual average overflows from about 50 down to two or three.
Central Control System Flows are monitored using continuous and intermittent monitors. Continuous monitors are permanently installed in more than 300 locations and use telephone lines and a wireless communication system to transmit data back to MMSD's Central Control System. Intermittent monitors are temporarily installed and rely on field crews to retrieve the data. Along with monitoring flow data, allows remote operation of the conveyance system. Goal is to ensure that treatment plant and conveyance capacity is utilized in the most efficient manner.
Wastewater Travel Times http://www.mmsd.com/projects/collection2.cfm
Deep Tunnel (In-Line Storage System) 19.4 miles long 300 feet below ground Up to 32 feet in diameter Storage capacity is 405 million gallons. Main component of $2.3 billion Water Pollution Abatement Program started in 1977. http://www.mmsd.com/projects/collection7.cfm
http://www.mmsd.com/projects/collection8.cfm
Sewer Overflows Separated Sewer Area: Storm sewer flow is discharged to local waterways through local storm sewers. Sanitary sewage travels into local sanitary sewers, MIS, and treatment plants. If local sanitary sewers or MIS cannot handle excessive infiltration tion into the sanitary sewer system, it is bypassed to nearby waterways. Flow also diverted to the deep tunnel, where it is stored until the plants have capacity to treat it. Combined Sewer Area: Sanitary sewage travels into local combined sewers, where it mixes with stormwater from runoff. Flow from combined sewers empties into the MIS, and excess flow is bypassed to nearby waterways at combined sewer outfalls. MIS conveys flows to the plants for treatment. If plants are not be able to handle excessive infiltration and inflow; i excess is diverted to the deep tunnel. If the deep tunnel is filled, it is discharged to local waterways.
Deep Tunnel System Benefits Improved water quality of local rivers, streams and Lake Michigan: Sewer overflows have been reduced from more than 50 per year to about 3 per year. Sewer system connections for 10,000 homes which formerly used septic systems. Nineteen small treatment plants in outlying areas were closed. Rock from tunnel used to protect against lakefront erosion, reconstruction of McKinley Beach, and creation of Summerfest Island.
http://www.mmsd.com/projects/collection7.cfm
MACRO Model Developed to evaluate the operation of the Milwaukee Metropolitan Sewerage District (MMSD) conveyance and storage system. Fortran Language program. Routing model that simulates movement of flow through Metropolitan Intercepting Sewer (MIS) subsystems to the following locations: Wastewater treatment plants South Shore Wastewater Treatment Plant (SSWWTP) Jones Island Wastewater Treatment Plant (JIWWTP) Inline Storage System (ISS) System overflow outfalls Separate Sewer Overflow (SSO) Outfall Combined Sewer Overflow (CSO) Outfall Flow continuity is maintained throughout each time step of the simulation.
Blending at Jones Island WWTP
Ways to Prevent Overflows Increase treatment / blending capacity Increase storage capacity Somehow manage the treatment and storage to reduce overflows
Operating Decisions Adjust VRSSI dynamically, or VRSSI min Increase blending (need permit, and also need to increase chlorination limit) Divert more/less to South Shore WWTP
Capital Investments Increase tunnel (ISS) volume: $15/ft 3 Increase pumping capacities from ISS to WWTPs: : 45 cfs pump costs $5 million Increase siphon capacity at JIWWTP (each siphon costs $12 million to upgrade to 400 cfs) Increase treatment capacity at JIWWTP: $1 million/cfs