Milwaukee Metropolitan Milwaukee Metropolitan Sewerage District Conveyance Sewerage District Conveyance

and Treatment Systemand Treatment System

MACRO made available byMACRO made available byEric Eric LoucksLoucks, CDM, CDM

MMSD Collection System MMSD Collection System OperationsOperations

MMSD operates an extensive system of sanitary MMSD operates an extensive system of sanitary sewers to collect, convey, and store wastewater sewers to collect, convey, and store wastewater originated by local sewer systems. originated by local sewer systems. Local systems are operated and maintained by Local systems are operated and maintained by municipalities within the District and those municipalities within the District and those contracted with MMSD. contracted with MMSD. Wastewater flows to the local systems, is Wastewater flows to the local systems, is collected by the District's intercepting system, collected by the District's intercepting system, and then conveyed to and then conveyed to MMSD'sMMSD's two wastewater two wastewater treatment plants. treatment plants.

Main Components of SystemMain Components of SystemMetropolitan Interceptor Sewer (MIS) Metropolitan Interceptor Sewer (MIS) System System Inline Storage System (Deep Tunnels)Inline Storage System (Deep Tunnels)Central Control System Central Control System

Metropolitan Interceptor Sewer Metropolitan Interceptor Sewer (MIS) (MIS) SystemSystem

A network of sanitary sewers that intercept A network of sanitary sewers that intercept wastewater from local sanitary and combined wastewater from local sanitary and combined sewer systems within service area. sewer systems within service area. Divided into seven subsystems for purposes of Divided into seven subsystems for purposes of flow monitoring analysis and system control. flow monitoring analysis and system control. Flows can be diverted between the subsystems Flows can be diverted between the subsystems for conveyance to either the Jones Island or for conveyance to either the Jones Island or South Shore treatment facilities, or to the South Shore treatment facilities, or to the District's Inline Storage System (Deep Tunnels), District's Inline Storage System (Deep Tunnels), where they can be stored until the plants have where they can be stored until the plants have available capacity for treatment.available capacity for treatment.

Inline Storage System (Deep Tunnels)Inline Storage System (Deep Tunnels)

Consists of 19.4 miles of tunnels 300 feet below Consists of 19.4 miles of tunnels 300 feet below ground that temporarily stores peak wastewater ground that temporarily stores peak wastewater flows that exceed treatment plant or MIS flows that exceed treatment plant or MIS capacities. capacities. Can hold up to 405 million gallons of flow and Can hold up to 405 million gallons of flow and was designed to eliminate overflows from the was designed to eliminate overflows from the separated sewer area and to greatly reduce separated sewer area and to greatly reduce overflows in the combined sewer area. overflows in the combined sewer area. Became fully operational in 1994 and has Became fully operational in 1994 and has substantially reduced the number of annual substantially reduced the number of annual average overflows from about 50 down to two or average overflows from about 50 down to two or three. three.

Central Control System Central Control System Flows are monitored using continuous and intermittent Flows are monitored using continuous and intermittent monitors. monitors. Continuous monitors are permanently installed in more Continuous monitors are permanently installed in more than 300 locations and use telephone lines and a than 300 locations and use telephone lines and a wireless communication system to transmit data back to wireless communication system to transmit data back to MMSD'sMMSD's Central Control System. Central Control System. Intermittent monitors are temporarily installed and rely on Intermittent monitors are temporarily installed and rely on field crews to retrieve the data. field crews to retrieve the data. Along with monitoring flow data, allows remote operation Along with monitoring flow data, allows remote operation of the conveyance system. of the conveyance system. Goal is to ensure that treatment plant and conveyance Goal is to ensure that treatment plant and conveyance capacity is utilized in the most efficient manner. capacity is utilized in the most efficient manner.

Wastewater Travel TimesWastewater Travel Times

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Deep Tunnel (InDeep Tunnel (In--Line Storage System)Line Storage System)

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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/collection8.cfm

Sewer OverflowsSewer OverflowsSeparated Sewer Area:Separated Sewer Area:–– Storm sewer flow is discharged to local waterways through local Storm sewer flow is discharged to local waterways through local storm storm

sewers. sewers. –– Sanitary sewage travels into local sanitary sewers, MIS, and treSanitary sewage travels into local sanitary sewers, MIS, and treatment atment

plants. plants. –– If local sanitary sewers or MIS cannot handle excessive infiltraIf local sanitary sewers or MIS cannot handle excessive infiltration into tion into

the sanitary sewer system, it is bypassed to nearby waterways. the sanitary sewer system, it is bypassed to nearby waterways. –– Flow also diverted to the deep tunnel, where it is stored until Flow also diverted to the deep tunnel, where it is stored until the plants the plants

have capacity to treat it. have capacity to treat it. Combined Sewer Area:Combined Sewer Area:–– Sanitary sewage travels into local combined sewers, where it mixSanitary sewage travels into local combined sewers, where it mixes with es with

stormwaterstormwater from runoff. from runoff. –– Flow from combined sewers empties into the MIS, and excess flow Flow from combined sewers empties into the MIS, and excess flow is is

bypassed to nearby waterways at combined sewer outfalls. bypassed to nearby waterways at combined sewer outfalls. –– MIS conveys flows to the plants for treatment. MIS conveys flows to the plants for treatment. –– If plants are not be able to handle excessive infiltration and iIf plants are not be able to handle excessive infiltration and inflow; nflow;

excess is diverted to the deep tunnel.excess is diverted to the deep tunnel.–– If the deep tunnel is filled, it is discharged to local waterwayIf the deep tunnel is filled, it is discharged to local waterways. s.

Deep Tunnel System BenefitsDeep Tunnel System BenefitsImproved water quality of local rivers, streams and Lake Improved water quality of local rivers, streams and Lake Michigan:Michigan:–– Sewer overflows have been reduced from more than 50 per year Sewer overflows have been reduced from more than 50 per year

to about 3 per year. to about 3 per year. Sewer system connections for 10,000 homes which Sewer system connections for 10,000 homes which formerly used septic systems. formerly used septic systems. Nineteen small treatment plants in outlying areas were Nineteen small treatment plants in outlying areas were closed. closed. Rock from tunnel used to protect against lakefront Rock from tunnel used to protect against lakefront erosion, reconstruction of McKinley Beach, and creation erosion, reconstruction of McKinley Beach, and creation of of SummerfestSummerfest Island. Island.

http://www.mmsd.com/projects/collection7.cfm

MACRO ModelMACRO ModelDeveloped 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) OutfallCombined Sewer Overflow (CSO) Outfall

Flow continuity is maintained throughout each time step of the simulation.

Blending at Jones Island WWTPBlending at Jones Island WWTP

Ways to Prevent OverflowsWays to Prevent Overflows

Increase treatment / blending capacityIncrease treatment / blending capacityIncrease storage capacityIncrease storage capacitySomehow manage the treatment and Somehow manage the treatment and storage to reduce overflowsstorage to reduce overflows

Operating DecisionsOperating Decisions

Adjust VRSSI dynamically, or Adjust VRSSI dynamically, or VRSSIVRSSIminminIncrease blending (need permit, and also Increase blending (need permit, and also need to increase chlorination limit)need to increase chlorination limit)Divert more/less to South Shore WWTPDivert more/less to South Shore WWTP

Capital InvestmentsCapital Investments

Increase tunnel (ISS) volume: $15/ftIncrease tunnel (ISS) volume: $15/ft33

Increase pumping capacities from ISS to Increase pumping capacities from ISS to WWTPsWWTPs: 45 : 45 cfscfs pump costs $5 millionpump costs $5 millionIncrease siphon capacity at JIWWTP Increase siphon capacity at JIWWTP (each siphon costs $12 million to upgrade (each siphon costs $12 million to upgrade to 400 to 400 cfscfs))Increase treatment capacity at JIWWTP: Increase treatment capacity at JIWWTP: $1 million/$1 million/cfscfs