Flora Pond Coalescing Filter Chamber and Detention System Rehabilitation

Joint Base Lewis McChord

Flora Pond is a 1.5 Million gallon storm water detention pond, with a large coalescing filter chamber and pre-settling storm water detention cell which utilizes a high water weir discharge system that is designed to capture millions of gallons of storm water conveyance from Main Base on Joint Base Lewis McChord via 60” diameter storm water pipes that run underneath I5 from Main base to North Fort.

This project was comprised of logging, with removal of hazard trees adjacent to previously excavated storm detention settlement contaminated soils, extensive dewatering and pumping efforts, contaminated soils removal, dry pond cleaning, mowing, and aerating, liner cleaning, coalescing filter chamber filter replacement, cleaning and retrofitting, and the procurement, installation and training of a photo eye water discharge and measuring system. It had an additional small area of work on JBLM’s main base for adding a catch basin, changing the curb and street profile, then forming and pouring a new curb and gutter and paving.

This project presented multiple challenges due to the complexity of the scope of work, and the very close monitoring and management of the potential adverse environmental impacts. This project presented another layer of complexity with having to accelerate the schedule for the pre-settling basin, as well as the work required in the discharge stream alignment, which all had to be done manually as the contract would not allow for any mechanical equipment in the outfall areas, which were extremely overgrown and very difficult to work.

Tunista Construction worked in lock step with the prime contractor, the United States Army Corps of Engineers, the Department of Ecology, and the Pierce County Health Department to ensure that all expectations were met for project management, execution and training.

This project was successfully completed on time and on budget even with having to work through the multitude of challenges that were attempting to delay or even stop the performance of the work.

This project represents Tunista Constructions ability to manage highly sensitive environmental areas, while managing contaminated soils and technically complex water filtering and discharging systems.