Minutes for February 19, 2008 Meeting

Meeting Notes
February 19, 2008

Corinne DeLeone (Seattle Public Utilities)
Samual Murchie (VOW)
Frank McDonald (Seattle Public Utilities)
Ingrid Wertz (Seattle Public Utilities)
Paul Chasan (Green Legacy Initiative)
Doug MartinJulie ClarkCole ClarkLiz HersethSteve QuartermanJake LynchKaren SchurrGayle GarmanRobin AmadonRichard FlemingMary Lou KnoxKevin StoopsKris FullerMichael Cornell

A. Monitoring report
Richard Fleming

  1. December 2-4, 2007 – 6 inches of rain fell in 40 hours (3.7 inches in 4 hours on the morning of December 3).
  2. Photos show water gushing out of the Densmore Drain; the grate fastenings were bowed and the SW grate corner was loosened. It looks like sediment that washed out of the drain was deposited as a 2 ft deep delta near the SE corner of the vault.
  3. Meridian Outfall- 2 stop logs had been removed and were on top of the outlet box, however, this drain seemed to be blocked and water was not leaving the lake at this location. Water was leaving lake at Hearthstone outfall, only.
  4. Large sediment plumes were observed, and photographed, where surface drainage pipes discharge into the Lake, and from old pipes below the water level. The largest plume was at the south end, near the dock east of the Aqua Theater. At the end of this dock, the secchi disc vanished at 20 cm. For comparison, the secchi disc could be seen to 3 ft at the end of the dock by the paddle-boat rentals.
  5. The lake was 1 foot higher than normal, and water over topped the walk by the small craft center.
  6. Bluegreen algae scum has been seen along the shoreline intermittently this fall and winter (photo from 12/13/07 on website).

B. Seattle Public Utilities report on the sewerage overflow in December
Ingrid Wertz, Corrine DeLeone, and Frank McDonald

  1. The overflow was from a sub-grade pump station for sanitary sewage at 107th and Midvale, which was installed in 1965 and updated in 1989. Normally this pumps sanitary sewage to the King County interceptor, but the installation includes a 36 inch diameter overflow to the Densmore Drain stormwater system if the pump is flooded.
  2. The pump continued to function throughout the storm, but overflowed to Densmore Drain for 15 hours. Seattle Public Utilities maintenance crews could not reach the system because of street flooding.
  3. The impacts – there was a 95,000 gallon discharge of combined stormwater and sanitary sewage into Green Lake. The percent of sewage in the overflow is unknown. Normal flow at this pump station is 50 gallons per minute, but was 200gpm during this storm. Seattle Public Utilities calculates that the 95,000 gallon discharge of overflow was less than 0.2% of average annual stormwater inflow to Green Lake, and 0.03% of total annual water input.
    1. There was a 24-48 hour period during which an increase in bacterial exposure and risk of disease would be expected.
    2. The main nutrient of concern is phosphorous. Assuming the 95,000 gallons was 50% sanitary sewage, Seattle Public Utilities calculated the added phosphorous at 1% of the average annual phosphorous load from stormwater inflows and 0.3% of average total inputs (based on Seattle Public Utilities phosphorus model for Green Lake).
  4. Mitigation is focused on fixing the flooding at 107th and Midvale. Seattle Public Utilities has no record of other sanitary sewage discharges into Green Lake (since 1989).
  5. Gayle stated that Friends of Green Lake would like water going into the lake to be cleaned before discharge, and noted also that Green Lake needs water inputs.
  6. She noted Friends of Green Lake’s concern that groundwater will be lowered by the action of large sump pumps used to keep excavations dry for large excavations at construction projects in Green Lake village, and whether this will reduce groundwater recharge of Green Lake. Frank McDonald indicated that City inspectors would require the removal of these sump pumps before the buildings are occupied.
  7. Seattle Parks and Recreation controls the lake level, and Lake outflows-it’s like a private sewer line.
  8. Green Lake outflows, low flows in the Densmore drain, and stormwater from Green Lake village, go to the circumferential drain around Green Lake. These flows join runoff from I-5 and E. Green Lake Way at a pump station near the Marshall School and the combined flow then discharges into Lake Union.
  9. Robin Amadon asked why the City doesn’t require new construction at Green Lake to include structures for stormwater infiltration.
  10. Mr. McDonald indicated the fix to the Densmore Drain grate was temporary, and that Seattle Public Utilities is developing a hinged grate as a final solution. The Densmore Drain discharges into Green Lake only when there is a “high intensity” rainstorm.

C. Green Legacy Coalition Presentation
Paul Chasan, greenlegacy@googlegroups.com

  1. Green Legacy Coalition is an advocacy group to preserve and obtain more open space in Seattle.
  2. He stated that we need to think long term and comprehensively
  3. The group is interested in extending the Pro Parks Levy. Friends of Green Lake members requested that Paul return with more specific ideas than just renewing the Pro Parks Levy. Friends of Green Lake members stated that they could not advocate a renewal without more specifics, or specific projects, because of unforeseen downsides to the last Pro Parks Levy.

D. Treasurers Report

Checking Account $996.80 $996.80
Savings Account $1611.55 +$20.00 donated +$2.41 int 1,633.96
Total Funds $2,630.76

Donations totaled $458.00 in 2007.

E. Old business

  1. Officer elections will take place at the March meeting- new Chairman and new
    Recording secretary for two-year terms.
  2. Karen will head the nominating committee.
  3. The 501(c)3 application is being worked on.
  4. King County- Seattle Public Health responded to Friends of Green Lake’s letter, and does not plan to do bacterial monitoring of both Green Lake beaches. Friends of Green Lake will continue to work on this issue.
  5. Kevin Stoops of the Department of Parks and Recreation reported that the draft Strategic Business Plan would be released for public review and comment at the end of March or beginning of April, and that 30 public meetings were planned to get feedback. The Strategic Business Plan will be a series of statements about Department objectives.

The meeting adjourned shortly after 9:00 p.m.