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Ward 16 Neighborhood Traffic Study

September 24, 2014

Nottingham-Ped-Choker

Lochmueller Group (Lochgroup) provided a neighborhood level street access and circulation study within the Saint Louis Hills neighborhood of the City of St. Louis, Missouri. The neighborhood has seen an influx of young families with children, which has prompted renewed interest in pedestrian safety. The resulting plan developed recommendations for reducing traffic volumes and speeds on neighborhood streets and improving the safety of pedestrians and bicyclists.

An extensive public engagement process was undertaken to better grasp the issues and desires of the neighborhood. A resident survey on transportation needs garnered almost 400 responses and multiple public meetings were held to form an in-depth view of the community’s needs. Additionally, interviews were conducted with the multitude of educational institutions in the study area, as well as City of St. Louis staff, to understand the operational concerns and constraints of the neighborhood.

A comprehensive data collection effort was undertaken to assemble an inventory of information from which informed recommendations could be developed. This data was utilized to evaluate potential treatments and either confirm or refute their viability. The data collected included:

The issues were then prioritized based on the preceding information. From these issues, counter-measures were developed along with a short-term/long-term priority, conceptual design schematic and estimated capital cost for each treatment. Some of the recommendations involved:

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Constructed Wetlands for CSO Treatment

Washington Wetland

The city of Washington, Indiana had a serious combined sewer overflow (CSO) problem. Worse yet, the city’s CSOs mostly flowed through open ditches, and all five eventually discharged into Hawkins Creek, which ran dry most of the time apart from when the untreated CSO discharged. In between rains, the water pooled and then dried up, concentrating pollutants.

Add to that the fact that Washington’s system, most of it dating from the 1930s, had little storage capacity. As little as one-tenth of an inch of rain produced CSOs. The city struggled with this problem for decades. Early attempts to abate it simply enclosed drainage ditches and creeks in large pipes, but didn’t address water quality. Facing federal mandates to clean up its water, the city was stuck.

With a population hovering just under 12,000 and a median household income of $34,000, costs were a critical concern. A 2002 study found that it would cost $39.9 million to properly capture and treat runoff, or $7,500 per household, roughly one-quarter of the average household income. By 2009, the cost had escalated to $53 million.

Washington Wetland During ConstructionLochmueller Group (Lochgroup) worked with Washington and the Indiana Department of Environmental Management to develop a solution that captures the CSOs, transports them to a storage basin, and then treats them using a constructed wetland. The Preliminary Engineering Report showed that the capital costs, when compared to the next lowest present worth alternative–Chemically Enhanced High Rate Clarification – reduced costs to $26.4 million, saving Washington’s residents $26.6 million. In addition, the city will save over $1.6 million annually in operations and maintenance. Diversion of stormwater will also reduce flooding of nearby residences and roadways.

Lochgroup’s design captures the first flush, up to the volume associated with a 1-year/1-hour storm event, in a 5-mg storage tank, pumping this to the wastewater treatment plant. Overflow from the tank— up to a 10-year/1-hour storm event—travels via two 84-inch pipes to a 21-mg, 27-acre constructed wetland for treatment. After treatment in the wetland, the effluent passes through a UV disinfection system before being discharged into Hawkins Creek.

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I-57/I-70 Rehabilitation

Highway and interchange design on I-57/I-70.

Increased congestion at the crossroads of two major freeways, I-57 and I-70, prompted the Illinois Department of Transportation (IDOT) to upgrade the section where the two highways merged through the City of Effingham. Lochmueller Group (Lochgroup) was hired to provide preliminary and final design of the roadway including five interchanges.

The additional lanes and interchange improvements would improve safety, reduce congestion, and allow for increased truck access for the movement of goods as the area continues to develop. As a result of the firm’s efforts on this $163 million project, Lochgroup received IDOT’s 2014 Award for Exceptional Consulting Engineering Service.

i57-70-2In all, Lochgroup designed the rehabilitation of 7.7 miles of roadway. This section of freeway is dual-marked and consists of 6 lanes and a 16-foot median. Lochgroup’s responsibilities also involved structural design for 11 bridges. Since the corridor serves as an essential national emergency route, the project also included the seismic rehabilitation of five bridges. Lochgroup developed in-house seismic retrofit details that restrain the bridge spans on their supports. The restraining devices were easy to construct, and they feature innovative indicator devices that will allow an emergency bridge inspector to evaluate if the restrainers are capable of resisting a second earthquake event or need to be replaced.

The bridge work also included design of three new bridges. One of the new bridges replaced the dual structures over US 45 and the Canadian National Railroad. Originally, the structures were only to be widened and rehabilitated. Due to the poor condition of one of the support piers, however, the project was re-scoped as a total replacement. This extra cost meant Lochgroup redoubled efforts to trim costs elsewhere to keep the overall project on budget. Lochgroup engineered a hybrid girder design as opposed to a standard grade 50 ksi steel plate girder. This reduced the amount of steel required for the plate girders by approximately 277,000 pounds saving at least $200,000.

i57-70A second new structure consisted of a 2-span bridge carrying a shared-use path over I-57/I-70 to support the local trail network. The bridge, which features a unique decorative railing, consists of a reinforced concrete deck supported by 40-inch steel composite web plate girders on a reinforced concrete pier and abutments. The abutments are wrapped around by Mechanically Stabilized Earth retaining walls.

The final new structure over Fayette Avenue is a 2-span bridge carrying a sidewalk, 4 lanes of traffic, and a turn lane. The schedule for design of the Fayette Avenue interchange was reduced by 14 months at IDOT’s request.

Final plans were broken into four phases to be constructed as funding became available and to allow local contractors to be able to bid on the projects. Construction was also coordinated with an adjacent project, I-70 over the Little Wabash River. The high potential for scour resulted in a complex structure design. By coordinating the two projects, Lochgroup saved IDOT approximately $1.2 million through changes to the construction phasing and compressing the design schedule from 18 to 12 months.

Another key to the success of the overall project was an intensive traffic management plan for multiple, overlapping construction contracts. This includes automated real-time work zone system with traffic sensors, video cameras, and message signs including alternate route detour and advance lane closure warning signs. Working with IDOT ITS managers and manufacturers, the plan resulted in few work queuing issues and accidents.

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Water Distribution System Improvements

north-vernon-water

north-vernon-water2This project replaced more than 47,000 linear feet of piping, or about 20% of the city’s aging water system infrastructure. This upgrade provided a more stable water supply to the customers and decreased the exposure to potentially harmful contaminants.

Lochmueller Group (Lochgroup) began with a comprehensive study of the city’s water treatment, storage, and distribution system. The study, including modeling of the system, assessed the system to determine adequacy to meet existing and projected demands. Alternative sources of water were evaluated including the development of a groundwater source to supplement or replace the existing surface water supply. Lochgroup was successful in helping the city secure various sources of capital to make this project happen, including grants and loans through USDA Rural Development and the Indiana Office of Community and Rural Affairs.

Lochgroup then designed the improvements and provided construction administration.

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