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water reclamation @ the GLY yard
by chris thompson | theme: sustainability
4.24.14

Our field crews and equipment yard personnel are passionate about finding sustainable solutions and feel empowered to drive changes that make a difference. Regardless of LEED status, GLY implements stringent mandatory jobsite recycling on every project we do, routinely resulting in the recycling of 90% or more construction waste on all of our project sites. That translates to approximately 10,000 tons/month of successfully recycled material diverted from landfills.

The GLY Equipment Yard team plays a crucial role in our waste management procedures and continue to come up innovative ways to conserve, reuse and recycle. The team as a whole takes a lot of pride in their contributions to GLY projects around Puget Sound, and in helping GLY be responsible stewards.

In 2012, we saw two opportunities: responsible cleanup of the many concrete slurry pans arriving from jobsites, and finding a sustainable way to capture, use and recycle rain-water. Since a storm drain system is not feasible at the Yard site, we thought proactively about on-site treatment system for used water with the intent to continue recycling the collected rainwater and water that drains away from the concrete slab over several wash cycles, and filtering the wash water in simple sediment tanks.

The team addressed these issues with two systems that ultimately work together as an ingenious Lean solution to discharging clean water from slurry pans, and reusing runoff.

water re 3pics3

1. Slurry pan off-loading. 2. Slurry Pan is rinsed with rainwater runoff. 3. Water drains into collection tank.

GETTING STARTED
The Yard Water Reclamation Process, which is now permitted by Snohomish County, didn’t happen over night. We first solicited estimates from an engineering firm, but ultimately decided to tackle it ourselves. As design developed, we recognized the synergy between the two systems. The resulting atypical solution was designed completely by the team as two separate systems that integrate:

  • Water Reclamation
  • Slurry Pan cleaning system

The Yard’s home-grown solution is effectively engineered to reclaim water from storm water runoff as well as the slurry pan cleaning process. In short: two old retention tanks were reclaimed from the site to capture and store rainwater in one dedicated tank and slurry water in another.

Reclaimed slurry pan water.

Reclaimed slurry pan water.

Water reclamation tank, which holds filtered slurry pan water.

Water reclamation tank, which holds filtered slurry pan water.

HOW IT WORKS
Reclaiming the concrete from the jobsites is the first step in the process. Concrete beds with water seals are custom-designed to work with our dumpster trucks to haul waste concrete from the jobsites to the Yard. After offloading the slurry pans, concrete solids are broken up and placed in the concrete recycle dumpster. It is then sent to jobsites for use as fill or to a concrete recycler where it’s repurposed as gravel for temporary roads, etc.

The concrete residue left in the slurry is pressure washed with rainwater runoff that has been captured by the new holding tank system and run through a pump system. The slurry water runs into sloped corner with a filter sock water separator designed to catch debris, oil and sediment. The oil rises to the top and is skimmed off, while the filtered water is drained into a Water Reclamation Tank.

There, the slurry water is stored, settles and is treated for PH balance using an automated PH monitoring system that injects CO2 as needed. The reclaimed water is then discharged through a bioswale drainfield system, exiting via perforated pipes to a level spreader in a large dispersion area with filter fabric and pea gravel. The water dispersed is clean and environmentally healthy for draining into the surrounding landscape and nearby small drainage creek—reclaimed but not reused.

However, the aforementioned rainwater is put to good use. Rain runoff slopes downhill to a filtered catch basin where it is filtered, stored in a separate rainwater tank, pumped and then recycled to wash slurry pans and trucks. And the cycle begins again, the water now heading for the Reclamation Tank for final dispersal.

"Every time we have a problem, we get different ideas from everyone and are able to overcome it. For example: algae bloom in tank. We painted it black to deflect light and added chemicals to kill the bloom."

| chris thompson, yard manager

 

water re 7

PH monitoring system that injects C02 as needed.

COST SAVINGS
The Water Reclamation system is engineered to be practical. Now that the system is in place, there’s very little expense. Plus they have a new storm drain system. It not only helps the environment, it helps the company by lowering water bills and eliminating the expense for a discharging system.

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