Bellingham Bioretention
There are many examples, nationwide, using bioretention at a larger scale to mitigate stormwater runoff from streets and parking lots. Let's take a look at a parking lot solution in Bellingham, Washington. This was designed to manage the stormwater runoff from the city hall parking lot.
The latter two pictures were taken less than three months after construction.
Some numbers:
| Tributary Area | 0.789 acres (parking and sidewalk area 100% impervious) |
| Total Precipitation Volume | 83,488 cf (624,490 gallons) |
| Previous Runoff Volume | 83,488 cf (assuming no evaporation) |
| Total Infiltration Volume | 72,047 cf (86% of total) |
| Total Raingarden Runoff Volume | 11,441 cf (14% of total) |
| (overflow periods determined by level recorder) | |
| Costs: | |
| Asphalt | $ 1056 |
| Concrete | $ 800 |
| Gravel | $ 12 |
| Labor | $ 1,690 |
| Equipment | $ 942 |
| Total cost | $ 4500 |
This bioretention installation was funded through a minimal sewer tax.
Contact:
William M. Reilly
Storm and Surface Water Utility Manager Phone: 360-676-6961
E-Mail: wreilly@cob.org
Bellingham Public Works Department
210 Lottie Street Bellingham, WA 98225