Tunnel And Reservoir Plan Research Articles

Modeling of a Transient Event in the Tunnel and Reservoir Plan System in Chicago, Illinois

Transient flow events can potentially damage infrastructure and threaten public safety in the vicinity of violent flow eruptions that occur where tunnel drop shafts interconnect with the surface-combined sewer system. Transient events have been observed in tunnels and at drop shafts in the tunnel and reservoir plan (TARP) system in Chicago on a number of occasions since operations first began in 1985. For the most part, the phenomenon has been controlled effectively by operating the system in a conservative mode through controlling the rate of filling. Nevertheless, more recently, not only water transients but also geysering events—the intermittent discharge of a combination of water and air from a hydraulic system—have occurred at the terminus of branch tunnels where controlled filling is not effective. The Metropolitan Water Reclamation District of Greater Chicago (MWRDGC), the operating agency for the system, has been prompted to develop engineering solutions to minimize transient flow occurrence and negative effects at the affected drop shaft locations. To this end, numerical modeling was conducted to investigate the cause and potential solutions. Such modeling included one-dimensional (1D) hydraulic transient modeling of a large domain in the system, followed by more detailed three-dimensional (3D) two-phase flow simulations within a smaller domain. The 1D approach revealed the interaction between localized events of interest and other transient flow features that originate far from the drop shaft under consideration. Computational fluid dynamics (CFD) modeling results show the complex interaction of trapped air and water in the tunnels. Even though more field observations are needed to test the accuracy of model predictions, careful interpretation of the results made it possible to pinpoint the problem and propose a solution. The findings also provided insight into the importance of considering both inertial instabilities as well as air–water interactions in geysering mechanics.

An Innovative Hydrologic and Hydraulic Modeling Approach for MWRDGC's Calumet Tunnel and Reservoir Plan (TARP) System

An Innovative Hydrologic and Hydraulic Modeling Approach for MWRDGC's Calumet Tunnel and Reservoir Plan (TARP) System

Sixty-five-year old final clarifier performance rivals that of modern designs

The Stickney plant of the Metropolitan Wastewater Reclamation District of Greater Chicago (MWRDGC), one of the largest wastewater treatment plants in the world, treats an average dry weather flow of 22 m3/s and a sustained wet weather flow of 52 m3/s that can peak to 63 m3/s. Most of the inner city of Chicago has combined sewers, and in order to reduce pollution through combined sewer overflows (CSO), the 175 km Tunnel and Reservoir Plan (TARP) tunnels, up to 9.1 m in diameter, were constructed to receive and convey CSO to a reservoir from where it will be pumped to the Stickney treatment plant. Pumping back storm flows will result in sustained wet weather flows over periods of weeks. Much of the success of the plant will depend on the ability of 96 circular final clarifiers to produce an effluent of acceptable quality. The nitrifying activated sludge plant is arranged in a plug-flow configuration, and some denitrification takes place as a result of the high oxygen demand in the first pass of the four-pass aeration basins that have a length to width ratio of 18:1. The SVI of the mixed liquor varies between 60 and 80 ml/g. The final clarifiers, which were designed by the District's design office in 1938, have functioned for more than 65 years without major changes and are still producing very high-quality effluent. This paper will discuss the design and operation of these final clarifiers and compare the design with more modern design practices.

Chicago's Underground Unveiled for the First Time Since Al Capone's Legacy Ended

Chicago's Underground Unveiled for the First Time Since Al Capone's Legacy EndedThe nation's most impressive combined sewer overflow (CSO) conveyance and storage system is now in its final stretch of design and construction. The Metropolitan Water Reclamation District of Greater Chicago's (District's) award-winning Tunnel and Reservoir Plan (TARP) continues to set precedence on how to effectively manage CSOs and improve the quality of environment and life in large...Author(s)Faruk OksuzCary HirnerSourceProceedings of the Water Environment FederationSubjectSession 62: Wastewater Conveyance and Overflows: Pipes, Pumps and TunnelsDocument typeConference PaperPublisherWater Environment FederationPrint publication date Jan, 2008ISSN1938-6478SICI1938-6478(20080101)2008:11L.4598;1-DOI10.2175/193864708788805026Volume / Issue2008 / 11Content sourceWEFTECFirst / last page(s)4598 - 4607Copyright2008Word count143

Surging in Urban Storm Drainage Systems

The ocurrence of surge and related problems is conceptually described in this paper, and then illustrated with both a mathematical model and field records. The paper also proposes and analyzes alternatives. It is noted that an urban storm drainage system could pressurize if its conveyance capacity is not sufficient or if it is also desinged for in-line storage. Surges caused by pressurization have been explained as a major source of transient problems such a sharp-peaked overflow, manhole blow-off, geysering, and structural damages. Severe shocks are produced whenever the surge front collides with an upstream end or a flow-restricting structure. The application is described of a mixed transient flow model to the Chicago Tunnel and Reservoir Plan (TARP), Illinois. It was used to study possible means of mitigating the surge problems. The most critical factor was found to be the surge intensity at the end of the pressurization process. Four possible operational and structral methods for in-line storage systems were investigated.

Tunnel and reservoir plan solution to Chicago's combined sewer overflow, basement flooding, and pollution

In 1890, the Metropolitan Sanitary District of Greater Chicago was formed to permanently protect the region's drinking water supply from devastating contamination by sewage. The solution was to excavate a massive canal across the continental divide and to thus reverse the flow of the Chicago River, causing it to flow into the tributaries of the Mississippi River and away from Lake Michigan. Later, sewage treatment works were constructed to treat dry weather flows.Each time rainfall exceeds 8.4 mm, the combined sewers' capacities are exceeded, and they discharge directly to the canal system on the average of 100 times per year without benefit of treatment. When the sewers and canal system are overtaxed, raw sewage backs up the sewers in Chicago and 51 suburbs, flooding streets, businesses, and home basements.In order to solve these problems on a regional basis, the Sanitary District in 1972 adopted the tunnel and reservoir plan (TARP). TARP is a second river system which is being constructed by boring tunnels up to 11 m in diameter in rock as much as 100 m under the city. When the surface sewers' capacities are exceeded, the excess flows will drop into TARP. Huge reservoirs totalling 157 000 000 m3 capacity will store the sewage until it can be gradually pumped back to the treatment works. Key words: sewage, combined sewers, overflows, water pollution, water quality, stream pollution, flood control, tunneling.

Water Resources for Chicago— History and Future

Combined sewer systems in much of the Chicago area negate many of the benefits of the largest and most advanced system of water reclamation plants in the world. On an average of 100 times a year, combined sewer flows overload District interceptors and surge into the rivers at 645 different points. Occasionally, the gates from Lake Michigan have to be opened to allow the rivers to relieve themselves in the Lake. The Tunnel and Reservoir Plan (TARP) will include 131.1 miles (211 km) of tunnels 150-ft - 300-ft (46-m - 91-m) below the rivers and the streets of the City. Drop shafts will intercept the flow in the combined sewers before it can reach the overflow points. The tunnels will convey this flow to reservoirs where it will be stored prior to being pumped to sewage treatment plants. Phased implementation of TARP will reduce the need for Lake Michigan water for dilution, making a larger proportion of the 3,200-cfs (90.6-m³/s) court allocation available for domestic and industrial use in the expanding Chicago metropolitan area.