Mill Creek Side Channel (Leber 2014)
#14-1001 #14-1001
Organization Green/Duwamish and Central Puget Sound Watershed (WRIA 9) Lead Entity
Sponsor City of Kent
Status Completed
Schedule Start Date: 12/4/2014 End Date: 10/16/2017
Category Category: Restoration
DESCRIPTION
The final phase of the Mill Creek Side Channel (Leber) project first removed and disposed of 4,000 CY of arsenic and weed-contaminated soil from the site (this material was disposed of in Republic Service's Subtitle D landfill in Klickitat County), and mixed another 4,000 CY of arsenic contaminated soil with clean soil and stockpiled this soil in two berms on-site above the 100-year floodplain. This work began in early May, 2016 and was completed by the end of June. Confirmation samples collected by AMEC Foster Wheeler consultants verified that all mixed and stockpiled soil was "clean" with arsenic and lead levels below the Ecology action levels of 20 and 250 milligrams per kilogram (mg/kg), respectively. After the contaminated soil at the site was remediated, excavation of the floodplain wetland began. Nearly 20' of overburden was removed to get the channel bottom down to the level that would provide consistent refuge and rearing habitat for salmonids during the spring outmigration (January - June). By the middle of August, 2016, surveying revealed that 83,000 CY of soil had been removed, with 7,200 CY of fill placed in the two berms (see "BEFORE" and "AFTER" as-built figures loaded in the PRISM attachments). All told, approximately 1,125 LF of new side channel was created that is tributary to Mill Creek (Auburn) and the Green River, and 2.03 acres of new backwater area was created. A total of 51 acre-feet of new floodplain storage was created by this excavation that will reduce flooding in surrounding areas. At the end of excavation, 2" of compost (a total of 2.400 CY) was worked into all surface soils to ensure that adequate soil quality and organic matter was present for planting. Next, large wood structures were added to the project site to help create a complex fish refuge and rearing habitat on the site. A total of 45 wood structures were installed adding 274 pieces of large wood (all were at least 15' long and 18" DBH with most 20' long, 24" DBH). This total large wood count included two extremely large cottonwoods that were found buried on-site (presumably from old lahar flows off of Mount Rainier) and were used as additional habitat logs. Lastly, the entire disturbed area was hydroseeded, planted and mulched. A total of 6.0 acres of area was hydroseeded with grass seed mix to stabilize soils and reduce weed infestation in late September, 2016. Native riparian plants were planted on 4.7 acres between October and December -(totaled sf from planting plan = 205,953 sf and converted to acres = 4.72 acres) (not including the 5,824 plants that were planted in Phase I under grant 13-1098). All containerized plants were mulched with wood chip mulch in February and March, 2017. For further information about planting, see the Leber Phase II Planting As-Built loaded in the attachments in PRISM. Since completion of planting and mulching, City of Kent Vegetation crews have maintained all plantings. This included weed whacking around plants to allow sunlight to reach all plants, and installing, maintaining and running an extensive irrigation system during the months of July, August and September to keep plants watered during an extremely dry and hot summer. Monitoring of fish use occurred in February and March and revealed that three different species of salmonids were using the new habitat (Chinook, coho and chum). Inundation monitoring continues but has so far revealed that the new floodplain wetland was at least partially inundated consistently between January 1st and May 26th (146 days) during the Chinook outmigration period. Vegetation monitoring was conducted in late August and early September. Results will be compiled soon and a report prepared before the end of 2018.
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FUNDING SOURCES
FUNDING ENTRIES FROM GRANT PROJECT AGREEMENT
TypeDateFunding OrgFunding ProgramMatchAmount
Requested05/23/2014Recreation and Conservation Office (RCO)Salmon State Projects$764,238.00
Requested05/23/2014City of KentMatch$1,413,615.00
Allocated12/14/2017Recreation and Conservation Office (RCO)Salmon Federal Projects$269,370.82
Allocated12/14/2017City of KentMatch$442,881.84
Allocated12/14/2017Recreation and Conservation Office (RCO)Puget Sound Acq. & Restoration$478,885.53
Spent07/10/2017Recreation and Conservation Office (RCO)Puget Sound Acq. & Restoration-$478,885.53
Spent12/13/2017Recreation and Conservation Office (RCO)Salmon Federal Projects-$269,370.82
Spent12/13/2017City of KentMatch-$442,881.84
Grant Project Agreement Totals Proposed Requested Allocated Spent Balance
Not entered $2,177,853.00 $1,191,138.19 $1,191,138.19 $0.00
OTHER FUNDING (Funding that is NOT in a grant project agreement)
TypeDateFunding OrgFunding ProgramMatchAmount
Other Funding Totals Proposed Requested Allocated Spent Balance
Grand Totals Proposed Requested Allocated Spent Balance
PRIMARY SPONSOR
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ALT PROJECT CONTACT
PROJECT MANAGER
PHOTOS

 
LOCATION
Chinook-Pop (ESU):Chinook-Puget Sound, Green River, Threatened
Chum-Pop (ESU):Chum-Puget Sound/Strait of Georgia, Not Warranted
City Areas:Kent
Coho-Pop (ESU):Coho-Puget Sound/Strait of Georgia, Species of Concern
County:King
HUC12:Mill Creek-Green River (171100130304)
HUC8:Duwamish (17110013)
Lead Entity Area:Green/Duwamish/Central Puget Sound Watershed (WRIA 9)
Legislative District:33
Pink-Pop (ESU):Pink-Odd Year, Not Warranted
Puget Sound Action Areas:South Central Puget Sound
Salmon Recovery Regions:Puget Sound
Sections:25
Steelhead-Pop (ESU):Steelhead-Puget Sound, Green River, Threatened
Township:T22NR04E
Watershed Administrative Unit:Lower Green-Duwamish
WRIA:Duwamish - Green
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Related Projects

  APPLICATION FINAL 
RESTORATION METRICS
Miles of Stream and/or Shoreline Treated or Protected (C.0.b)
0.05mi0.30mi
Instream Habitat Project    
Total Miles Of Instream Habitat Treated (C.4.b)
0.03mi0.30mi
 Channel reconfiguration and connectivity (C.4.c.1)    
Acres Of Channel/Off-Channel Connected Or Added (C.4.c.5)
2.00acres2.00acres
Instream Pools Created/Added (C.4.c.6)
0.000.00
Miles of Off-Channel Stream Created or Connected (C.4.c.4)
0.03mi0.21mi
Miles of Stream Treated for channel reconfiguration and connectivity (C.4.c.3)
0.07mi0.30mi
 Channel structure placement (C.4.d.1)    
Acres Of Streambed Treated for channel structure placement (C.4.d.4)
2.00acres
Miles of Stream Treated for channel structure placement (C.4.d.3)
0.03mi0.30mi
Number of structures placed in channel (C.4.d.7)
43.0045.00
Pools Created through channel structure placement (C.4.d.5)
0.000.00
Yards Of Average Stream-Width At Mid-Point Of Worksite (C.4.d.6)
15.00yd
Riparian Habitat Project    
*Total Riparian Acres Treated (C.5.b.2)
7.00acres4.80acres
*Total Riparian Miles Streambank Treated (C.5.b.1)
0.30mi0.30mi
 Planting (C.5.c.1)    
Acres Planted in riparian (C.5.c.3)
0.50acres8.00acres
Miles of streambank planted (C.5.c.4)
0.11mi0.30mi
 Riparian Plant removal / control (C.5.h.1)    
Acres of riparian treated for plant removal/control (C.5.h.3)
5.00acres8.00acres
Miles of streambank treated for plant removal/control (C.5.h.4)
0.03mi0.03mi