De-wasting the dewatering process with Lean

It used to take us about 800 hours a year to figure out what to do with small amounts of groundwater in construction sites – until King County Industrial Waste Engineer Ed Abbasi decided to try something different.

During construction, workers may need to pump groundwater away from the site they are working at, which is called dewatering. Often this water is sent to a surface water body, like a lake, through a storm drain. But if the water does not meet a certain criteria is goes into the sewer. When it goes to the sewer, the project needs a permit from King County and the local sewer agency.

Ed noticed that we used the same process for every sewer permit, regardless of the size of the project. This meant that contractors, local sewer agencies, and our King County staff had to gather to review documentation regardless of whether the project was a small new development, or a large tunneling project. Using principles of Lean, Ed realized that this unnecessary time and attention spent on smaller projects was in fact, waste, since the small project dewatering would never have much impact on the sewer system.

To combat the identified waste, Ed created a countermeasure, or a plan for change. He suggested developing a new process for small projects that would use a presumptive approach. If project is small and uses best management practices, it is presumed that there will be minimal effect on the sewer system.

Ed began to collect data to test his countermeasure idea. He interviewed partners in the construction industry, he spoke with his colleagues at King County, and he met with leaders of the local sewer agencies. He used the data to refine his project and developed criteria for the types of projects that would be eligible for an expedited dewatering permit:

  • Site is not contaminated.
  • Site is less than 1 acre.
  • Project will discharge less than 25,000 gallons per day (gpm) to the sanitary sewer.
  • Site has a sedimentation tank.

He checked back with colleagues and our leaders in King County. When he had gained support for the criteria, he and his team developed a simpler application form and a standard authorization letter that outlined the requirements all small projects would have to meet.

Impact: The new process went live in March 2016 and is expected to save King County over 400 hundred hours of staff time per year. Regional partners also benefit since there will be less back-and-forth between King County, local agency staff, and builders of small projects.

Ed’s work is a great example of a small change that reaps big results, while increasing customer service, supporting the regional economy, and protecting water quality. He plans to measure the success of the project and make adjustments in the future, following the PDCA cycle model for continuous improvement.

Contributed by Erika Peterson and Bill Wilbert

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