April 1, 2009Painted into a corner. Up a tree. Stuck behind the 8-ball. We’ve all been there at some point or another — in a situation in which there is no easy way out, one in which the alternatives for improving the situation present a different set of challenges entirely.
In many cases, this is the situation in which municipal collection system operators find themselves today as they try to manage aging systems that have been largely neglected, while facing new pressures related to regulation and an increasing population. Meanwhile, the chances of expanding budgets to tackle the challenges are remote, even in the best of economic times.
One recent trend in the sewer collection systems involves the concept of infrastructure asset management. Put simply, an asset management program is one in which infrastructure is managed in a way that meets service expectations in the most economical way over the life span of the asset — i.e., getting the most bang for your buck.
An asset management plan covers multiple facets, including inventory and condition assessment, through to repair and new construction. One sometimes overlooked part of an effective asset management plan is preventative maintenance. Conceived properly, an effective preventative maintenance program can put a utility on the road toward effective asset management and sustainability by making the most effective use of existing department time and resources.
Preventative maintenance comprises a variety of activities. Two common preventative maintenance techniques include sewer cleaning to remove grease and other debris and chemical root control to keep lines free of obstructions. According to the U.S. EPA, blockages related to grease, roots and debris are the cause of 75 percent of all sanitary sewer overflows (SSOs) in the United States. (Wet weather inflow and infiltration (I/I) and line breaks comprise the majority of the remainder.)
Implementing a preventative maintenance program that addresses these issues not only help sewer systems stay in compliance with regulatory agencies, but it also reduces the manpower strain related to emergency response calls.
The first step is identifying the source of the problem, according to John Fletcher, Mid-Atlantic regional manager for Duke’s Root Control. While that sounds simple enough, Fletcher said it’s a common pitfall. “There are cases in which cities set up preventative maintenance plans based on assumptions that may not be correct. It’s important to really investigate the true cause of the problem, then set up a plan to fix it. Otherwise, you may be treating the symptom and not the cause.”
The City of Macon, Ga., recently revamped its approach to preventative maintenance, and with the help of a chemical root control program, was able to reduce overflows and increase system efficiency.
With a history tracing back to 1880, the Macon Water Authority plays an integral role in delivering water and sewerage services to residents in Macon and surrounding Bibb County. The authority operates approximately 1,200 miles of interceptor and main sewers serving more than 40,000 customers.
Beginning in 2000, Macon embarked on a program to reduce SSOs and develop a more efficient maintenance program. It began by commencing a sanitary sewer evaluation study (SSES) to identify problem areas.
Unfortunately for Macon and sewer conveyance and water distribution manager Darryl Macy, crews were all too often busy dealing with emergency calls to address the core problems head on.
“Before we started this process, we were a reactive group,” Macy said. “We would stop what we’re doing, then go across town to address a spill. We needed to be a bit more methodical in our planning so that once our crews were in the field to do a job, they stayed out there.”
In some cases, cities will develop a list of areas where spills are most frequent and target them for more regular cleaning intervals — “hotspot” cleaning. However, this approach doesn’t address the underlying causes and only further taxes department resources.
One area that came to the forefront in Macon’s SSES was root infestation, so the authority implemented a chemical root control program in areas where the problem was most severe, as identified by the authority’s spill database. Before implementing a chemical root control program, approval from the wastewater treatment plant is required to ensure that the chemicals do not adversely affect the biological processes at the plant. Typically, the herbicides used in the chemical root control process are small compared to average daily flow and do not have negative impacts.
Macon used a request-for-proposal approach to hire a specialist root control contractor. “We liked the idea of bringing in a specialist so that we don’t have our guys dealing with chemicals and processes they’re not familiar with,” Macy said. “Instead, they can concentrate on cleaning, televising and right of way cleaning.”
Macy said the authority began the root control program in the most severely impacted areas and has increased the amount to its current level of about $300,000 per year (about 200,000 lf of pipe). He said the program paid immediate dividends. “In the first year we began to see quantifiable results,” Macy said.
The number of spills attributable to roots went from 35 in 2003 to four in 2006 (with a peak of 40 in 2004). The total spill volume decreased from more than 900,000 gals in 2003 to 457,182 gals in 2004 all the way down to 31,435 gals in 2006. Typically, in trying to reduce SSOs, cities will look to increase capacity and/or reduce I/I into the sewer. But as Macon showed, these approaches may not necessarily be the most effective.
As a result of fewer stoppages and spills, Macy’s crews were able to increase the amount of cleaning and maintenance activities because of the decreased emergency calls. Crews were able to increase the footage of lines cleaned from 186,000 lf in 2003 to 1.6 million lf in 2006. Likewise, CCTV inspections went from 88,000 lf in 2003 to 583,000 in 2006, and right of way clearing went from 35,000 lf in 2003 to 543,000 lf in 2006.
The turnaround in Macon was so complete that the authority was honored with the Georgia Association of Water Professionals’ best-run system in Georgia award in each of the last two years in which it was eligible.
On the Right Path
Now that Macon Water Authority has decreased its spills and implemented a proactive approach to sewer system maintenance, the effects have been seen in many areas. “We’re able to spend more time doing our due diligence work and not chasing spills across the county,” Macy said. “Our cleaning, televising and right of way clearing numbers are up 600 to 700 percent over five years ago, with the same number of people and trucks.”
In fact, Macy was able to dedicate one crew as an I/I reduction crew, which will further aid the authority in its goal of eliminating overflows. Macy said the authority’s perception among the public has also turned 180 degrees. “We get notes from people telling us they appreciate the job we’re doing,” he said. “And it’s usually a thankless job.”
Other benefits have included a buy-in from the organization from top to bottom, improved crew morale and earning the trust of the Macon Water Authority board and directors. The approach may be becoming more common as cities are taking better inventory of their systems and becoming more in-tune with the impacts of their decisions.
“We’re starting to see a lot of cities keeping closer track of what they are doing and documenting the results,” said Stuart Tillery, southeast account manager at Duke’s Root Control Inc. “There are now several cities that are committed to treating lines if they see a root so they can make a true assessment of the pipe. In addition, once they have treated the roots, more than likely the pipe is going to be in good shape and can continue to be an asset for years to come.”
James W. Rush is editor of Trenchless Technology.