The story profiled the lack of drainage in Ballard’s soil conditions, and the safety concerns this raises.
Monthly Archives: March 2011
Found in Montana’s books:
Mont. Code Ann. §7-31-4201 et. Seq.
“The legislature declares that the control of ditchwater in inhabited areas of Montana is affected with the public interest. The purpose of this part is to prevent drowning of children in ditches filled or partially filled with water within the limits of an incorporated city or town.”
Children really do drown in ditches filled or partially filled with water.
As the ponding continues and the Combined Sewer Overflow (CSO) issue is not being resolved, the residents on 77th and 29th Avenues have contacted outside experts for more analysis.
We have been working with a hydrologist at Shelterwood Consulting, who graciously offered to present to SPU and the Task Force at our last meeting. The presentation can be found here: http://www.shelterwoodconsulting.com/Ballard_Bioretention_ponds.html
In summary, the consultant confirmed and emphasized these ponds were installed on top of Vashon Glacial Till (clay or hardpan), and therefore the water does not “perc” (or infiltrate) through this layer once it is saturated. The perc and soil tests performed by SPU indeed revealed the native soils would not be appropriate for infiltration-based bio-retention ponds. Additionally, these tests were conducted during the middle of the summer when soil is dry. SPU also neglected to add a “correction factor” to the test results, which would have shown even worse perc rates. Best Management Practices (BMPs) advise against installing bio-retention ponds with the type of soil and perc test results found in most of this pilot project area.
Additionally, although it cannot be confirmed without more testing, we believe the perch water (or groundwater) could possibly be drained as well if underground drainage were installed, exacerbating the CSO issue.
As a result of the consultant’s analysis and our extensive monitoring since implementation, we on 77th and 29th have changed our viewpoint:
Since these bio-retention ponds are not a viable Combined Sewer Overflow (CSO) solution, we would like to see this pilot project stopped, the ponds removed, the parking strips returned to their original state, and other CSO solutions sought.
Please see our updated issues on the Issues tab, and find our suggested alternative solutions on the new Options tab. Additional suggestions are welcome and will be added to the list.
Bugs have begun hatching in and emerging out of the Raingardens.
From a neighbor yesterday:
“There are a gazillion….gross brown flies the color of sand that are crawling around the fetid standing water of the cell on the North Side of NW 77th nearest to the alley. I find them to be really gross.”
Another neighbor sent pictures from today:
These Raingardens are considered to be functioning by SPU (even though the curb inlets are still blocked), but they still have inches of water on Friday afternoon (after 72 hours) from the earlier storms:
The vactor truck came later to pump them out:
“I have noticed that all the non-draining cells (and there are more of them now) are starting to have weird things growing in them AND THEY STINK!”
“It seems like the vactor truck was very selective in what he pumped. I saw some at 75th & 31st with quite a bit of water that weren’t pumped. Definitely lots of crap growing in them and odors starting to be emitted even on these windy days.”
Under the new March 2011 tab, we have posted pictures of the ponds during this month’s spring squalls.
These ponds, considered “green” and functioning by SPU, have been full now for ten days. The ground is saturated all the way to the Glacial Till (clay) below, and the water is not draining. In the deeper spots, 8 to 11 inches of water pools and sits. Two-year-old and four-year-old boys live in the house adjacent to this.
During yesterday’s rain, the cells overflowed, and the water began pouring over the berms: two cells looked like one.
The black asphalt plugs still restrain water from the street; even while overwhelmed, these ponds are not functioning as originally designed (even though they are marked as “green” by SPU).
Saturday night, teenagers came to hang around the ponds, and Sunday morning, footprints covered the top of the slope, compacting the absorbing soil that was already pressed down by driving rain. The design plans may not have taken these factors into account.