Big Tujunga & Pacoima Canyons

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Big Tujunga Dam PROJECT SUMMARY   The 2009 Station Fire was the largest fire in Angeles National Forest (est. 1892) recorded history and burned over 160,000 acres in the San Gabriel Mountains. Approximately 87% of the watershed tributary to Big Tujunga Reservoir was burned, making sediment deposition inevitable during subsequent storm events. The storms that occurred in the wet seasons after the fire increased sediment accumulation in the reservoir by more than one million cubic yards. The sediment in the reservoir can impact the operation of the valves and reduce the capacity for water conservation and flood control. Sediment removal is necessary to maintain the operability of the dam and protect the communities and environment downstream of the dam. Pursuant to the California Environmental Quality Act (CEQA) a Mitigated Negative Declaration (MND) has been prepared. You may view the document by clicking the links in the Environmental Documents section. Pursuant to the National Environmental Policy Act (NEPA) an Environmental Assessment (EA) is being prepared. A public scoping meeting was conducted by the United States Forest Service on July 24, 2012 in Tujunga, CA and included this linked Big Tujunga Presentation. A public review period for the draft EA will begin in fall 2013. Click here for the Expanded Project Description. http://dpw.lacounty.gov/lacfcd/sediment/prj.aspx?prj=3

Big Tujunga Dam PROJECT SUMMARY
The 2009 Station Fire was the largest fire in Angeles National Forest (est. 1892) recorded history and burned over 160,000 acres in the San Gabriel Mountains. Approximately 87% of the watershed tributary to Big Tujunga Reservoir was burned, making sediment deposition inevitable during subsequent storm events. The storms that occurred in the wet seasons after the fire increased sediment accumulation in the reservoir by more than one million cubic yards.
The sediment in the reservoir can impact the operation of the valves and reduce the capacity for water conservation and flood control. Sediment removal is necessary to maintain the operability of the dam and protect the communities and environment downstream of the dam.
Pursuant to the California Environmental Quality Act (CEQA) a Mitigated Negative Declaration (MND) has been prepared. You may view the document by clicking the links in the Environmental Documents section.
Pursuant to the National Environmental Policy Act (NEPA) an Environmental Assessment (EA) is being prepared. A public scoping meeting was conducted by the United States Forest Service on July 24, 2012 in Tujunga, CA and included this linked Big Tujunga Presentation. A public review period for the draft EA will begin in fall 2013.
Click here for the Expanded Project Description.
http://dpw.lacounty.gov/lacfcd/sediment/prj.aspx?prj=3

Christopher Stone, Project Lead for the Pacoima Sediment Removal Project stated at Eldridge Park’s October 22, 2013 community meeting that Maple Canyon being the selected SPS for a portion of the 7.2 MCY dredge of sediment from Big Tujunga Reservoir, no sediment would be trucked to Sun Valley Land Pits.

Mr. Stone’s comment is not consistent with a fair estimate of total truck trips impacting the East San Fernando Valley, considering three sources of Sediment Debris:

  • 4.6 MCY for truck trips to Sun Valley of the overall 7.6 MCY from Pacoima Reservoir – if after subtracting 40% or 3 MCY marketable was processed in situ – not transported,

  • filling up Maple Canyon with 4.4 MCY of the overall 7.2 MCY from Big Tujunga Reservoir – leaving 2.8 MCY for truck trips to Sun Valley,

  • and 5.71 MCY from 113 Debris Dams from West and South areas for truck trips to Sun Valley,

  • totaling 14.71 MCY transported by 8 CY single load dump trucks equalling 1,838,750 truck trips over a 20 year project construction timeline with intensive truck trips occurring from 2016 to 2023. Even averaged out over twenty years, that’s a completely intolerable 183,875 truck trips every two years from Pacoima Reservoir, Big Tujunga Reservoir, and some 30 debris dams to Sun Valley’s Land Pits broadcasting carcinogenic air pollution dust, causing public safety risks and road damage.

References:

http://dpw.lacounty.gov/lacfcd/sediment/

http://dpw.lacounty.gov/lacfcd/sediment/dcon/420.pdf

http://dpw.lacounty.gov/lacfcd/sediment/dcon/425.pdf

http://dpw.lacounty.gov/lacfcd/sediment/dcon/429.pdf

Maple Canyon SPS was established in 1981 for previous cleanouts of the reservoir with the current remaining capacity up to 4.4 mcy. It currently holds approximately 3 mcy of sediment and the existing fill covers an area of approximately 28 acres. Excavated material will be transported approximately 1.8 miles to the existing SPS. Bulldozers and other heavy equipment would be operated continuously at the SPS in order to spread and compact the sediment. The addition of 4.4 mcy of sediment from this project will increase the SPS footprint by 29 acres. Areas within the increased fill footprint would be cleared and grubbed prior to the placing of sediment.

Reference: http://dpw.lacounty.gov/wrd/Projects/bigtujunga/Expanded_Project_Description.pdf

This magnitude of near 2 million truck trips, indeed, any number of truck trips in any event is unacceptable to communities most severely affected: Sylmar, Sun Valley, Pacoima, North Hollywood and to the East San Fernando Valley generally. The moral hazard to respiratory health, general health, road repair, safety, and social disruption is unacceptable. Mechanical conveyance is the most cost-economic method considering the social, health, ecologic costs of truck trips. Existing conveyances may be employed for cost savings.

Reference: https://docs.google.com/document/d/1S4WnuSC__PsCafMamCrdy9sOEbtF3HFIksvYsXaiyl0/edit?usp=sharing

There does not have to be alternatives pitting flora and fauna against health risks from hundreds of thousands of truck trips. Rewilding the foothills and canyons allows for natural deposition of alluvial sediment. Slope stabilization techniques allows for lowered and more controlled mud and debris flow before accumulating in Pacoima reservoir.

What has not yet been studied is the creation of cottage industries in situ sorting out sale-able component materials dredged from the reservoir: silt, decomposing organic matter, rock and gravel, and the deployment of a new system of smaller reservoirs to mitigate future volumes of sediment otherwise managed in more ‘business as usual’ DPW and LADWP failed methodologies that attempt to control nature rather than working and designing with nature.

Making up 70 years of neglect from allowing debris to negate the reservoir mission to protect downstream urbanized flooding in a twenty) year sentence of 7.6 cubic million yards transported from Pacoima Reservoir and 7.2 MCY from Big Tujunga Reservoir making 1,825,000 MCY single load haul truck trips each with a 8 cubic yard capacity terminating in historic ‘Pit District’ otherwise known as “Sun Valley” – is criminal and cannot be tolerated nor allowed to proceed as a plan.

Look, in lieu of this ill-fated Los Angeles County DPW plan, to mitigations from a proposed 170,000 truck trips over a 2 year period our community of activists extracted from LADWP over their Tujunga Spreading Ground dredge plan – being mechanical conveyance. If we can protect the community from 2 years of 170,000 truck trips, we certainly shall protect the same community from 20 years of 182,500 truck trips every 2 years – the equivalency of the LACDPW community-destroying ‘sediment management’ plan,

We can do this folks.

https://www.facebook.com/groups/AdvocacyforPacoimaCanyon/permalink/522815537796323/

Location: Pacoima Dam is located in Pacoima Canyon, 4 miles northeast of San Fernando, California. (Thomas Guide Page 4642-F7) Fire Event(s)*: 2008 Marek Fire 2008 Sayre Fire 2009 Station Fire Watershed Burned: 76% Amount of Sediment to be Removed:Between 3 - 5.4 Million Cubic Yards Removal Method:TBD Disposal Location:TBD Required Permits:U.S. Army Corps of Engineers California Dept. of Fish and Game Regional Water Quality Control Board United States Forest Service Community Meeting Dates: TBD *Heavy sedimentation is expected for the five years following the fire event. **Alternative removal methods are being investigated. http://dpw.lacounty.gov/lacfcd/sediment/prj.aspx?prj=2

Location: Pacoima Dam is located in Pacoima Canyon, 4 miles northeast of San Fernando, California. (Thomas Guide Page 4642-F7)
Fire Event(s)*: 2008 Marek Fire
2008 Sayre Fire
2009 Station Fire
Watershed Burned: 76%
Amount of Sediment to be Removed: Between 3 – 5.4 Million Cubic Yards
Removal Method: TBD
Disposal Location: TBD
Required Permits: U.S. Army Corps of Engineers
California Dept. of Fish and Game
Regional Water Quality Control Board
United States Forest Service
Community Meeting Dates: TBD
*Heavy sedimentation is expected for the five years following the fire event.
**Alternative removal methods are being investigated.
http://dpw.lacounty.gov/lacfcd/sediment/prj.aspx?prj=2

Various References:

DPW Sediment Management Debris Basins

DPW Sediment Management Strategic Plan

DPW Sediment Removal Projects

DPW Big Tujunga Reservoir Sediment Removal Project Presentation

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