Thousands of gallons of clean rainwater draining off the roof deck onto bare soil turning into thousands of gallons of water that’s too dirty to discharge without treatment. With pre-planning, a temporary collection system could have been developed and installed to contain, collect and convey the clean water to an existing drainage system. Without such a system, the dirty water had to be treated chemically to reduce the turbidity enough to discharge to the storm system.
I inspected the open catch basin the next day to see if it was fixed, and this is what the contractor had done to keep turbid water out. I have nothing against doing this, but, since this does keep water out, flooding ensues. Flooding is okay if the catch basin is in a low spot and no one needs to work in the area.
I told the contractor that they might want to look at the storm system and see if there is a point where they can install a concrete plug temporarily and use the system for conveying the turbid water to their treatment system.
This is caused by a broken 16 inch waterline. Fortunately, all of the muddy water was contained in a 72″ storm pipe with a valve. Water was then pumped to a Chitosan-enhanced Sand Filtration (CESF) system for treatment to 5 NTUs for discharge to a creek. Knowing this project was going to be constructed over several winter seasons, we specified the CESF system in the contract.
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