First, we called the City of Bellingham Public Works Department, and asked for assistance. They suggested that we start by sweeping all the adjacent paved areas, in order to remove as much dirt and dust as possible, using dry methods. Then, they suggested that we figure out a way to collect ALL the wash water, and pump it to landscaped areas on our property, or pump it to the wastewater treatment facility, via one of our indoor toilets or sinks. They told us we'd need a permit to vacate the sidewalk, so we got one.
Minutes after learning this, it started to rain! We felt very fortunate - we walked around the building with our raincoats on, studying the drainage. We made a drainage map, and observed which storm drains were collecting water from around our building and parking lot. We discussed how to "pre-clean" the area by sweeping, and options for collecting the wash water. We chose a landscaped area on our property to receive the wash water. Why did we do all this? Because stormwater from the area around our store drains directly to Bellingham Bay, without any treatment. Pressure wash water typically contains paint, debris, sediment, and other compounds. None of these compounds are allowed to be discharged into the storm drain system. It was important to us to do the job right.
Sweeping is important because it keeps dirt and debris out of the waste water stream. We were surprised at how much dirt we swept up, even though sweeping is one of the regular steps we take to clean up our parking lot area.
Next, we blocked two storm drains with heavy plastic sheeting and sand bags. This forced the wash water to pool, so we could easily collect it with a shop vacuum.
Here's the other drain, along Meridian Street. Because we did the job on a dry day, very little water reached the blocked drain, and it was easy to collect the water. We also used a water reducing pressure wash nozzle, further reducing the amount of water.
We tied the shop vacuum to a handtruck to facilitate transport to our landscaped area, where we emptied it into a small depression in the lawn. Because we were generating such a small amount of water, absorption kept pace with water generated and captured.
Although blocking the storm drains and capturing the water made the job take a little longer, we were surprised at how easy it was to do the job right. Thanks to Marj Leone for the photos and text, and to the RE Store staff. Way to go!