Case Studies

Ditching Inefficient Aeration

When a broken shaft caused a malfunction in one of the brush aerators at the Village of Liberty, N.Y., wastewater treatment plant (WWTP), the village worked with its engineers, Delaware Engineering, to develop a plan for repair and upgrade.

Scope

Blast from the Past

In the late 1970s, the old Tullahoma, Tenn., wastewater treatment plant (WWTP), built in 1955, was overloaded and deteriorating. The City of Tullahoma and its consultants—Barge, Waggoner, Summer and Cannon—began an extensive evaluation of different treatment options for the new plant, including an oxidation ditch, in-channel clarifiers and the Sanitaire Intermittent Cycle Extended Aeration System (ICEAS) for a sequencing batch reactor (SBR) process.

Adopting Aeration

Driven by compliance with more stringent water treatment standards, the Fond du Lac (Wis.) Wastewater Treatment Plant leveraged an upgrade opportunity to improve beyond limiting ammonia effluent levels. The plant improved energy efficiency, reduced maintenance and operating costs, and eliminated bypasses into Lake Winnebago during high rainfall.

Scope

Up to Code

The Village of Johnson Wastewater Treatment Facility (WWTF) was among the first in the state of Vermont to meet newly enacted secondary treatment requirements when it began operation in 1970. After legislative changes more than two decades later called for stricter discharge limits on phosphorous, ammonia and residual chlorine, the Village of Johnson sought to increase the facility’s flow capacity—especially its ability to handle the high seasonal flows associated with storm events.

Solution

Foresight Design

A recent $10.2-million upgrade at the regional wastewater treatment plant operated by the Portage (Pa.) Area Sewer Authority doubled the facility’s daily flow rating to 2 million gal per day (mgd) and brought the previously deficient peak rating up to 6 mgd. Added peak capacity was a primary goal of the project to correct hydraulic limitations that previously required repeated bypasses during heavy rainfall events caused by inflow and infiltration (I&I) into the collection system.

Caught Up in Time

City officials in Sullivan, Mo., were notably proud in 1988 when their new aerated wastewater treatment lagoon began operation. Within five years, however, the plant was essentially obsolete due to the reclassification of the effluent-receiving stream by the state’s regulatory agency and apprehensions about the stability of the site’s underpinning geology.

Rising to a New Challenge

The Newville Borough Water and Sewer Authority (NBWSA) in Newville, Pa., has over 6.5 miles of sewers in the borough, serving a population of 1,326. An additional 5.7 miles of gravity sewers and one pumping station serves surrounding municipalities.

Project Background

Surging Ahead

The city of Portage is a former borough within Portage Township in Cambria County, Pa. Before a $10.2 million upgrade, the Portage Area Sewer Authority was operating in a facility built in 1972.

Project Background