IMPROPER EXCAVATION WAS PRIMARY CAUSE OF FAILURE, SAYS 2^ND SWIFT CREEK PUMP STATION REPORT

Town Council to Review Findings during Tuesday Work Session

CARY, NC – According to a second report commissioned by the Town of Cary and released today, the large area excavated by a private contractor too close to the existing force main pipe and without proper pipe restraint caused the incident this summer at the Town of Cary’s Swift Creek Regional Pump Station during which millions of gallons of untreated waste made its way into downstream waters.  Hired in August by the Town of Cary to assess the cause(s) of, response(s) to, and impact(s) from the June 23, 2006 event, California-based Brown and Caldwell’s findings along with 20 recommendations will be presented to and discussed in detail by the Cary Town Council during a special work session on Tuesday, October 10, 2006 at 4:30 p.m. at Cary Town Hall.

“In Cary , our goal is always to do the right thing, which is why we asked for this comprehensive, professional, and objective evaluation,” said Town Manager Bill Coleman.  “We hire the best employees, contractors, and consultants to work for our community, and while the Swift Creek project is no exception, it’s clear that the project team could have done more.”

Over the last six weeks, Brown and Caldwell ’s forensic team has been conducting site visits, collecting and analyzing data, and interviewing people involved with and impacted by the incident.   Among the key findings of their report are:

• Excavation around the existing force main pipe undertaken by the contractor in the days preceding the incident was too sharp and steep, causing the surrounding soil to become unstable and fail.

• While digging very close to the existing force main, the contractor did not properly restrain the existing pipe, which eventually became dislodged and leaked sewage.

• The incident would likely have happened regardless of the heavy rains that occurred just prior to the failure.

• The original undersized thrust block used to help restrain the existing force main was not a primary cause of the failure.

• The project team—Laughlin-Sutton, Black & Veatch, and the Town of Cary —should have stopped the construction project prior to the incident in light of the slope problems.

• In addition to the short-term impacts of the sewer spill, there could be long-term impacts on Swift Creek and Lake Wheeler .

Not wanting to wait for the outcome of the report to make improvements, the Town now has the piping on hand to create a system bypass should it be necessary again.  Permanent bypass valves have been a design standard for all new regional and terminal Cary pump stations for the last 3-4 years, and staff is evaluating all existing regional and terminal pump stations to determine the best way to create bypasses in those should they be necessary.  Also, Town staff who may have to be part of a public works emergency response team have undergone national incident management system training through FEMA to ensure that their response is as efficient and effective as possible.

In addition, Town staff has begun an internal risk assessment for all of the Town of Cary ’s water and sewer facilities to apply the lessons learned from the incident as well as recommendations from the report throughout the organization.  Coleman has also asked for “a full analysis of the Town’s response plans for utility failures as well as project management operations to ensure that our high expectations are always met on every project the Town undertakes.”

Regarding the impacts on downstream waters, Coleman said that “ Cary will be working with Wake County , DENR, the City of Raleigh , environmental experts, and others to further assess and take steps toward improving the health and vitality of Swift Creek and Lake Wheeler .”

The Cary Town Council approved Coleman’s request and $200,000 for this the second investigation into the June 23^rd incident after he concluded that an initial assessment conducted by Black & Veatch lacked sufficient specificity as to cause and provided recommendations that were too generic.

“As an open, learning organization, we needed to know exactly what happened so we can continue to improve,” said Coleman.

In August 2005, the Town of Cary began the planned expansion of its Swift Creek Regional Pump Station at 7800 Holly Springs Road .  The Town hired a contracting firm–Laughlin-Sutton–to handle the construction and an engineering firm–Black & Veatch–to oversee the project on the Town’s behalf.  Black & Veatch also designed the construction expansion.  

As part of the expansion, the contractor excavated a large area near the existing pump station.  On June 23, a soil embankment collapsed, and the force main pipe critical to the station’s operations was dislodged.  In order to repair the pipe, workers had to shut down the pump station.  About 20 percent of the pump station’s daily waste stream was diverted to another pump station, and much of the rest of the waste was taken away via a massive pump and haul operation. 

Even so, during the five days between the pump station’s shutdown and the activation of an onsite bypass, Cary estimated that as much as 7.9-million gallons of untreated waste—or about 32 percent of the station’s average flow for a 5-day period—likely made its way into Swift Creek.  No fish kill was observed, but the situation closed several downstream lakes as well as Holly Springs Road for a time.

Each year, the Town of Cary processes about 4.4 billion gallons of wastewater for Cary , Morrisville, RDU, and the southern portion of the Research Triangle Park .

Read the complete report in HTML or PDF at www.townofcary.org.

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