Last week, the Lehigh Valley received record rainfall in the amount of more than 8 inches beginning on Thursday, September 30, and continuing overnight into Friday, October 1, 2010.

 For Lehigh County Authority (LCA) and the municipalities that are connected to its regional sewer system, the storm brings the issue of leaking sewer lines into sharp focus. During the storm, sewer flows increased rapidly over a few short hours from a normal flow of about 7 million gallons per day to approximately 20 million gallons per day on Friday.

LCA now has three facilities in place to address “wet weather flow” like this, including a pump station in the Spring Creek Road area of Lower Macungie Township, a pump station in Allentown’s Lehigh Parkway area, and a new flow equalization basin (FEB) in Fogelsville. The FEB project was just completed and put into full operation earlier in the week, so this storm event was its first use. While LCA plans to analyze the FEB’s operation during last week’s storm to learn how to optimize its use during wet weather events, officials say the basin was successful in holding back up to 3 million gallons of flow during the peak of the rain event, which may have helped to reduce overflows downstream of the facility.

All three facilities were working at full capacity to handle the high flows brought on by the storm. However, the quick onslaught of the storm overwhelmed the system in a few areas, causing sewer manholes to overflow in the Lehigh Parkway area, just upstream of the pump station located there. Four of LCA’s sewer manholes were overflowing in addition to other non-LCA sewer manholes that were observed overflowing during the storm event. Because the municipal, LCA and Allentown pipe networks are an interconnected system, overflows may have been experienced in other locations throughout the system as well, in addition to possible bypassing of the Allentown treatment plant.

Based on operational data and field observations, LCA believes the overflows began at about 3:30 a.m. on Friday and continued intermittently until about 2:30 p.m. On Friday afternoon, LCA crews spent time in the Little Lehigh Parkway raking up debris caused by the Little Lehigh Creek flooding and the sewer manhole overflows, and spreading lime to neutralize the affected areas and control odors at any of manholes that showed evidence of overflows. Crews will continue to work on the affected manholes to repair damage caused by the force of water flowing through the system.

LCA crews also spent Friday afternoon and Saturday inspecting manholes on the Western Lehigh Interceptor upstream of the City’s Little Lehigh Parkway. No evidence of sewer overflows was observed upstream of the area that was inundated on Friday.

Sewer overflows occur in this region during storm events due to a high rate of rainwater entering the sewer system, typically through a combination of unauthorized connections such as sump pumps, roof drains and floor drains, manholes that are not designed to prevent rainwater leakage into the system, leaking private lateral sewer lines, public sewer lines that allow groundwater to enter the system, and aging stormwater systems that do not adequately contain stormwater runoff. Sanitary sewer systems are not designed to handle stormwater, and yet the flows experienced during rain events indicate that rainwater inflow is the primary cause of these peak flows and subsequent overflows.

In late 2009, the U.S. Environmental Protection Agency issued an order for all the municipalities using the regional sewer system that flows to the City of Allentown treatment plant to eliminate sewer system overflows that have plagued the system for quite some time. Municipalities throughout the region have their own sewer systems providing service to residents and businesses, and connect into LCA’s or Allentown’s regional interceptors to transport their wastewater to the treatment plant.

LCA and the municipalities in Western Lehigh County are actively pursuing the investigation and rehabilitation of sewer systems to eliminate such overflows. The Sewer Capacity Assurance and Rehabilitation Plan (SCARP) was adopted by LCA and the municipalities it serves in 2009, and they are now working through a partnership approach on programs to address high-priority areas identified through the flow-monitoring work conducted over the past three years.

Municipalities included in this partnership have already begun work in their communities to identify homes with unauthorized connections or sewer lines and manholes that need to be prepared. LCA has recently completed the construction of the FEB to help contain peak flows during storm events, as well as pursuing a flow modeling program, interceptor rehabilitation work, and providing overall leadership and support for the municipalities involved in the partnership. It is expected that this work will continue for several years before significant improvements will be realized, as the problem stems from tens of thousands of individual sewer connections that must be inspected and addressed if they are contributing rainwater to the system.

In the July 25, 2010 edition of The Morning call, a lengthy article discussed the important issue of sewer system overflows into the Little Lehigh Creek. If you read the article, you may be left wondering what all this means. Is it safe for my family to swim or go fishing in the creek? Is my drinking water safe? What about the environmental impact? These are questions that trigger and emotional response of sadness and fear, as we all have a natural connection to our precious water resources.

A few important clarifications are required to help put the media’s coverage of this issue into perspective.

First, it is important to note that the article was focused primarily on incidents when the City of Allentown’s wastewater treatment plant was bypassed, resulting in 33 million gallons of raw sewage being discharged into the Little Lehigh Creek over a 10-year period. The article did not clearly explain that the location of this bypass is at the Kline’s Island Treatment Plant in Allentown, just upstream of the creek’s confluence with the Lehigh River. The photos in the newspaper show residents in the creek upstream of this location, which would not have been affected by these bypass incidents.

However, other incidents have occurred over the years where sewer manholes have overflowed upstream of KITP, including sewer overflows within LCA’s service area. Like the KITP bypasses, these have been isolated incidents that are well documented  and reported (i.e. not a secret), occurring exclusively during extreme wet-weather conditions that cause the sewer systems to become overwhelmed with the inflow of rainwater. Immediately following the subsidence of floodwaters that result from these rain events, our systems return to normal operations, which is to say that there is no lasting effect on our sewer systems, nor any continuous or ongoing discharge of raw sewage to the creek.

For example, most of LCA’s municipal signatories are served by our Western Lehigh Interceptor facilities. According to LCA records, the most recent incident involving sewage overflows along the Western Lehigh Interceptor occurred in October 2005, when Tropical Storm Tammy dumped approximately 10 inches of rain on our region within a 2-day period. The severe flash-flooding that occurred during this storm resulted in many areas of the Little Lehigh Creek, and our parallel sewer lines and associated manholes, to go “under water.” In effect, the creek banks were so severely flooded during this tropical storm that our manholes were overwhelmed with creek water and rain water, resulting in some mixing of highly diluted sewage into the floodwaters. And as soon as the floodwaters receded, the overflows also ceased.

LCA conducted follow-up inspections over the next several days, finding no lasting effects on our sewer system facilities, the surrounding rights of way, or the creek. These inspections, and all the subsequent inspection and rehabilitation work LCA has completed since this time, help us to verify that there is no ongoing flow of raw sewage into the environment at this location.

Another area of concern is in the Little Lehigh Parkway, where LCA and other municipalites have facilities that come together to join with Allentown’s system. Here again, overflows have been experienced in some isolated cases when extreme wet weather has caused region-wide flooding, resulting in excessive rainwater inflow into our sewer systems. Keep in mind that these sewer systems are not designed to handle “storm water.” The rainwater enters the sewer system typically through a combination of high groundwater levels and the flow of clear water from unauthorized connections such as sump pumps, floor drains and improperly maintained manholes.

What’s next? Communities in Western Lehigh County are actively pursuing the investigation and rehabilitation of sewer systems to eliminate such overflows. The Sewer Capacity Assurance and Rehabilitiation Plan (SCARP) was adopted by LCA and the municipalities we serve in 2009, and we are now working on plans and programs to address high-priority areas identified through the flow-monitoring work conducted over the past three years. Of particular note is the issue of removing rainwater inflow from unauthorized connections such as sump pumps and floor drains. This is one of the major contributors of rainwater into the system that causes the overflows discussed by The Morning Call. The community must work together to determine the best way to identify and eliminate such sources of rainwater from the system if eliminating the overflows is truly a goal the community embraces.

Food for Thought: The sole purpose of public sewer systems is to protect our environment through proper treatment of waste. While we certainly would like to eliminate all sewer system overflows, and we are working collectively as a region toward that goal, we believe the overflow incidents that have occurred to date pose far less risk to environmental health and safety than the situation that would exist if we had no centralized sewer collection and treatment system in place. Take a look at other areas of the world (and even some areas in the Lehigh Valley!) where leaking septic systems have caused tremendous environmental damage and pose great risks to human health. It was not too long ago (40 years or so) that the Lehigh Valley region looked at this issue and realized the need to regionalize sewer service in order to protect local waterways. The investment has been costly and will continue to challenge our communities as repairs are needed, but the overall improvement in local utility services and environmental protection cannot be underestimated.

Read the full article from The Morning Call.

In late 2009, the U.S. Environmental Protection Agency issued an order for all the municipalities using the regional sewer system in central Lehigh County to eliminate sewer system overflows that have plagued our system for quite some time. Municipalities throughout the region have sewer systems providing service to residents and businesses. These sewer systems are connected to LCA’s regional pipeline that transports waste to the City of Allentown for final treatment. Click here for a system overview map.

How do the overflows happen? The primary issue we are all faced with is rainwater infiltrating the sewer system during wet-weather events. This occurs when sewer lines are cracked and need to be repaired, when customers have gutter systems and sump pumps connected to the sewer system, when manholes are not sealed properly, etc. Removing the rainwater from the system will be a long and expensive process requiring a partnership of all municipalities and customers.

Municipalities in Western Lehigh County have formed a partnership to work on solutions to this problem under a program called Sewer Capacity Assurance and Rehabilitation Program (SCARP). Municipalities adopted the SCARP plan into the Act 537 plans in January 2010, and we are all working together on the next steps, which is an evaluation of flow monitoring data to determine the priority areas that need to be looked at closely, and determining the most meaningful ways to reduce rainwater infiltration.

SCARP fact sheet

Full SCARP document

Appendix A

Appendix B