Features

January 2007, Vol. 19, No.1

Remediation to the Rescue

Continual biological augmentation brings new life to an old sand filter, eliminating the need for costly replacement

remediationtotherescue.jpg Douglas J. Nelson and Mark C. Noga

District 1 of Savannah, N.Y., was in trouble. Its cluster system, constructed in the late 1980s, was beginning to show its age. In early 2002, the district came under increased regulatory scrutiny because it was failing to meet its discharge permit
limits. Operations staff felt the district’s violations were directly related to its sand filter, which had a long-standing history of ponding. As a result, the sewer district and its residents had a tough decision: Replace the sand filter at a significant cost to the community or face a consent order. The district decided to pursue an alternate course.  Read full article  

 

Two Birds, One Stone
    

Creative design gives this North Carolina disposal facility a dual purpose

twobirds.jpg Ed Bradford and F. Roger Watson

In upgrading its septage receiving facility, the Metropolitan Sewerage District (MSD) of Buncombe County, N.C., was keeping up with the times.

Like many utilities, MSD — which is responsible for collecting and treating the wastewater generated in the greater Asheville, N.C., area — has seen its responsibilities change over the years. The 151,000-m3/d (40-mgd) French Broad River Water

Reclamation Facility had been collecting and treating wastewater from Asheville and five surrounding communities since it was placed on-line in 1967. In 1990, MSD took over ownership and maintenance of the local collection systems, which total more than 1450 km (900 mi) and serve approximately 130,000 people.  Read full article   

 

Going for the Kill
 

Alternative disinfection technology demonstrates advantages for wet weather applications

goingforthekill.jpg Peter E. Moffa, Daniel P. Davis, Chris Somerlot, Dan Sharek, Brian Gresser, and Tom Smith

Treating stormwater and combined sewer overflows (CSOs) is a major concern for many utilities. While such well-established technologies as chlorination and dechlorination often are used for high-rate disinfection of CSOs, some cities have been testing alternatives. For instance, the City of Akron, Ohio, recently tested a powdered bromine technology that has been implemented successfully in Japan. Akron found that the powdered bromine compound — known as

bromochlorodimethylhydantoin (BCDMH) — performed favorably compared to sodium hypochlorite.

BCDMH disinfects with a combination of hypobromous acid and hypochlorous acid, which are powerful oxidizing agents. According to EBARA (Tokyo), the only known company that produces BCDMH for the wastewater industry, BCDMH achieves better bacteria kills than a comparable dose of chlorine. And unlike other chemicals that decay rapidly and require onsite generation, powdered bromine can be stored for more than a year without a decrease in effectiveness. These factors make the technology suitable for intermittent treatment of wastewater, including wet weather applications. Read full article 

 

Operations Forum Features

Digital Dosing

Advancements in metering pump technology hold great promise for utilities

digitaldosing.jpg Michael Volk

Used to inject treatment chemicals in virtually every water and wastewater facility, metering pumps should be considered separately from virtually every other type of pump for two primary reasons. First, metering pumps, also called dosing
pumps, are much more than merely pumps, as they incorporate elements of process management and water quality control. In a real sense, they are instruments, as well as machines used to move liquid, as they directly affect the amount of chemicals used to treat water and wastewater. Second, metering pumps have undergone several distinct technological changes during the past 60 years, compared to most other pump types, which have evolved little during this period. Some changes in materials or manufacturing techniques have occurred for every type of pump, but changes in the way a metering pump operates truly have expanded the scope of what a metering pump can achieve.  Read full article 

 

What Every System Owner Should Know About CIPP

When using cured-in-place pipe, collection system owners and engineers must consider a host of factors to ensure quality

whateverysystem.jpg Stephen E. Lindsey

During the past decade, the cured-in-place pipe (CIPP) industry has undergone tremendous change, complicating efforts by sewer system owners to ensure quality and value in their investments. Although prices for CIPP have dropped

dramatically, many companies providing CIPP lack the knowledge or capacity to produce a first-rate end product. As profit margins have narrowed, many in the industry have decided to cut the cost of raw materials by using inferior resins, catalysts, and liner tubes. These companies also have sought to decrease installation time to reduce their labor costs. Although such measures sound fine in theory, at times they have proven disastrous in the field.  Read full article 

 

Lateral Moves

Recapturing capacity is easier than expected
 

lateralmoves.jpg Jim Peters, Edward G. Malter, and Bob Schaefer

When eliminating infiltration and inflow (I/I), fixing the publicly owned components of the collection system only solves part of the problem. Ten years of rehabilitating gravity mains and manholes had recaptured 35% of capacity previously lost to
I/I in Springfield, Mo., but an estimated 65% of all I/I was still entering the sewer system via privately owned laterals. The city still had about three sanitary sewer overflows (SSOs) a year because of I/I-related peak flows.

Although the city needed to minimize I/I to protect the environment, control collection and treatment system costs, and meet the terms of a consent decree, staff at Springfield’s Division of Sanitary Services initially were concerned that minimizing I/I from laterals would be too onerous. Most residents were unaware of any problems with the service lines on their properties and would be resistant to the cost and disruption involved in repairing them.

However, data collected during collection system surveys showed that there were eight sources of I/I on private property, and some were simple to fix. So, the city began working on an approach that would minimize the effect on ratepayers and maximize the amount of capacity recaptured by the division.  Read full article