Rescuing Wastewater Facility Stranded Capacity

Finding “low-hanging fruit” at wastewater facilities to increase capacity and improve operational reliability can pay significant benefit by maintaining service levels without committing to large-scale capital expenditures.

“The key is seeking out inexpensive adjustments to current operating facilities that may allow postponing, changing, or eliminating major projects and expenditures,” said Bob Ohlund, PE, Dudek’s vice president for water and infrastructure.

“The best question an agency can ask itself is, ‘Before we abandon, reconstruct, or tear something down, is there additional value we can get from it?’” Ohlund said. “Reviewing assumptions and data is essential. It can be a relatively quick process that can produce immediate savings without the time lag involved in a master plan.”

Ohlund offers the following project examples:

Reuse, Not Disposal – The Dudek team worked Lee Lake Water District in Corona which was concerned with increasing cost of treating excess effluent to tertiary standards for permitted discharge into a stream. Dudek designed an option to achieve zero discharge to the stream by constructing percolation ponds on adjacent property, requiring only secondary treatment, and treating effluent to tertiary levels only when required to meet irrigation need sfor a golf course, landscape irrigation and dechlorinated tertiary fail-safe disposal to the stream. The long-term cost savings and avoidance were significant.

Stranded Capacity – A program run by Inland Empire Utilities Agency (IEUA) found excess capacity in treatment units that were underutilized or had flow restrictions. By testing and evaluating processes, the regulatory agencies could re-rate two regional plants to allow higher flows and avoid or postpone costly expansion projects.

Energy Savings – In addition to reusing digester gas and installing solar panels, IEUA’s team found that much of the recycled water was produced at their lower-elevation central plant and then pumped to higher elevations for use. At the same time, an upper-elevation plant near a major reuse market was bypassing flow downstream because of permitted redundancy restrictions.

IEUA obtained a “bubble” permit for the upper plant, establishing treatment redundancy at the under-utilized downstream central plant. IEUA can now produce recycled water at the higher zone plant and save significant, long-term pumping costs.