Integrated Wet Weather Improvement Program
Regulatory roadmap for cost-effective environmental and public health improvements for Clean Water Act Compliance.
The City of Lakewood selected CT as the prime consultant for the development of the city’s Integrated Wet Weather Improvements Plan (IWWIP) pursuant to its obligations under its National Pollutant Discharge Elimination System permit. The goal of the project was to develop an integrated plan consistent with EPA’s June 2012 Municipal Stormwater and Wastewater Planning Approach Framework.
The IWWIP provides the regulatory roadmap for the best, most cost-effective environmental and public health improvements for Lakewood’s compliance with the Clean Water Act. Development of solutions were complicated by the nature of Lakewood’s complex sewer system, the age of the infrastructure, private property contributions to wet weather flows, and a web of financial implications to the budgets of both the city and its residents.
CT worked with the city to characterize the existing collection system during Phase 1 by providing continuous field services including inspections, pollutant sampling, and flow monitoring. By developing an intimate understanding of the city’s complex sewer system, CT developed a detailed H&H Model, which represents flows from sources to discharge points. The model includes approximately 3,000 nodes and is calibrated using dry and wet weather flows, and pollutant loadings from sewage and other urban runoff sources.
Phase 2 of the IWWIP included alternatives screening, alternatives analysis, and costing/ranking of alternatives. The result was a preferred plan including $156 million in improvements over approximately 25 years. This is a significant reduction in cost compared to complete sewer separation ($604 million) and the original Long-Term Control Plan ($309+ million).