I mentioned several months ago that the streets were torn up and a sizable project had commenced in the neighborhood. Eventually, it was obvious the various corners and intersections were being altered and it became obvious that catch basins were being built on a grand scale. I made some enquiries of the City of Portland and soon some information flowed my way re the project’s purpose and costs.
Kate Goudschaal (C of P, Bureau of Environmental Services) wrote to me: “You are correct that the major construction on the 16 stormwater facilities is nearly complete. There are a few small final restoration items that still need to take place to close-out the project but the facilities themselves are ready for planting this coming spring.”
“This project was designed in response to the retrofitting of 26 Underground Injection Control (UIC) sites in the area. UIC sites, also known as sumps, are large, vertical, perforated pipes that are installed underground to collect stormwater and allow it to infiltrate into the ground while pollutants and other sediments are slowly filtered out. Retrofitting the sumps reduced the amount of stormwater they could collect which resulted in the need to create additional stormwater management options in the area.”
“The solution was to build a certain number of above ground stormwater facilities to adequately manage the stormwater runoff in the area. Green streets function in the same way as sumps but on the surface of the street – horizontally as apposed to vertical and underground. The substrate and plants selected for the facilities are specifically chosen for their ability to filter pollutants and clean the stormwater before it infiltrates the groundwater system and/or is discharged to local waterways.”
“The facilities along (your street) are a little different however. Structurally, they are similar to other facilities around town, but they all have a lining installed in the bottom to prevent the water from immediately filtering into the ground water. Instead, the water filters through the plants and substrate, is cleaned and then collected in a perforated pipe in the bottom of the facility that conveys the water to the local stormwater pipe system in the area. The stormwater pipes then carry the cleaned stormwater to discharge in the Columbia Slough.”
“This project lies within the City Council’s adopted Columbia South Shore Wet Field Wellhead Protection Area which is the designated ground water source for Portland if/when the reservoir drinking water system fails. So, protecting the ground water and managing stormwater in this area is particularly crucial. Stormwater management in this area helps maintain the integrity of the aquifer as well as cleans street runoff before it reaches the sensitive Columbia Slough waterway.”
Ms. Goudschaal offered the following information when I enquired about the cost of the project to build 16 Green Basins: “The project was awarded to Brant Construction out of Vancouver, Washington for a winning bid value of $605,628.00. The 16 stormwater facilities made up roughly 40% of the overall project budget and came in at about $242,000.00. So, with 16 facilities included in the portion of the project, the total construction cost (start to finish) per facility came to approximately $15,125.00. This project is funded….through water and sewer utility rates.”
The following links from Ms.Goudschaal provide a wealth of information about this project and the greater picture involved in the handling of storm water:
There is a wealth of knowledge on this topic (and much more) on our website. I encourage you to do more research here: Columbia South Shore Well Field Ground Water Aquifer: http://www.portlandonline.com/water/index.cfm?c=29785
Sustainable Stormwater Management: http://www.portlandonline.com/bes/index.cfm?c=34598
Green Street Program overview: http://www.portlandonline.com/bes/index.cfm?c=44407&
Watershed Management: http://www.portlandonline.com/bes/index.cfm?c=32184
If you have an interest in such a project for your area, check out the information to become informed.