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Mallard II

Summary

Mallard II is a wooden-hulled clamshell dredger[2] used to maintain levees on the San Francisco Bay Salt Ponds.[3][4] Mallard II was constructed in 1936,[5]: 45  and is "probably the oldest operating dredge in California";[6]: 51  she is owned and operated by Cargill Salt.[4]

Mallard II near the Dumbarton Bridge in 2021
History
NameMallard II
OwnerCargill Salt
In service1936
StatusIn service
NotesOldest operating dredge in California
General characteristics
Class and typeDredger
Length80 ft (24 m)[1]
Beam34 ft (10 m)[1]
Draft7 ft (2.1 m)[1]
Mallard II moving mud, with its bucket outstretched

History edit

Mallard II was built by the Leslie Salt Company (now Cargill) in 1936, and has maintained the levees of the salt ponds ever since,[6]: 51  except for a brief period during World War II during which she was used to retrieve artillery shells from the floor of the Bay near Mare Island and the Port Chicago Naval Magazine.[7] Over time, she received extensive upgrades (including a modern engine, steel A-frame and boom).[6]: 51  The steel frame was installed by Bethelehem Pacific's San Francisco shipyard in 1954, at which point she maintained levees on over 30,000 acres (12,000 ha) of ponds in the South Bay as well as Napa County.[1] She has been described as a "floating wood-and-metal dinosaur", with a 2 cu yd (1.5 m3) bucket capable of moving as much as 2,000 cu yd (1,500 m3) of mud per day.[1] While dredging, she is anchored by "spikes", and moves from place to place by "grabbing hold of the sea floor".[8] Mallard II was used to construct such watercourses as North Creek; in 1972 she was briefly idled while the Leslie Salt Company sought dredging permits from the United States Army Corps of Engineers.[9] Salt ponds on which Mallard II is used must be kept at a higher water level than they otherwise would be, owing to her draft.[10]

In 2002, she was used for the Eden Landing wetland restoration project, for which Cargill donated the use of the dredger and 400 man-hours of labor.[8]

As of 2007, she was the only wooden-hulled clamshell dredger operating in San Francisco Bay, as well as "probably the oldest operating dredge in California", responsible for maintaining 200 miles (320 km) of levees between Hayward, Redwood City and San Jose.[6]: 51  She repairs and maintains approximately ten miles (16 km) of levee per year.[7] Mallard II can operate for more than two months without being refueled.[7][11]: 61  As of December 2020, she was still operational.[11]: 54 

Levees edit

The levees surrounding the San Francisco Bay Salt Ponds date to the late 1800s, and were mostly constructed to reclaim land for agricultural purposes; the area enclosed by them was later used for salt production.[5]: 45  In addition to their role in operating the salt ponds, the levees protect Bay Area cities like San Jose from being flooded by high tides.[12]

Due to factors such as erosion and subsidence, the levees require regular maintenance. Dredging material to increase the levees' height, the "least expensive technique available", consists of moving Mallard II into a salt pond through a set of locks and using her clamshell bucket to remove material from a borrow pit; this material is then deposited atop the levee.[13] When Mallard II is present in a salt pond, waterfowl hunting is not permitted.[14]

A December 2020 permit for a wetlands project issued by the California Department of Fish and Wildlife provided for maintenance of salt ponds to be carried out by the still-operational Mallard II, using the existing system of dredge locks, referred to as "the most technologically and economically feasible method for solar salt production in south San Francisco Bay".[11]: 54  While it would be possible to reduce some of the adverse impacts of levee maintenance (mostly caused by the existence of the dredge lock system) by using a "transportable dredge", it was found that such a dredge would require more frequent refueling (every two weeks, as opposed to every two months with Mallard II), as well as the use of large trucks and cranes to reposition it; Mallard II, therefore, was found to be the "most feasible alternative".[11]: 61  A 2005 estimate of expenses for levee maintenance in the area put the cost of using Mallard II at approximately $50,000 per month.[15]

References edit

  1. ^ a b c d e "Leslie Salt Co. Dredge Repaired". The Napa Valley Register. Napa, California. 1954-12-30. p. 2.
  2. ^ Benton, Cris (30 September 2005). "The Mallard II". Hidden Ecologies. University of California Berkeley. Archived from the original on 9 July 2021. Retrieved 6 July 2021.
  3. ^ "Staff Report: Salt Ponds" (PDF). San Francisco Bay Conservation and Development Commission. October 2005. Archived (PDF) from the original on 2021-07-09. Retrieved 2021-07-06.
  4. ^ a b Krause, John (2007). "2007 Self-Monitoring Report: Baumberg Complex – Hayward, California, Eden Landing Ecological Reserve" (PDF). California Department of Fish and Game.
  5. ^ a b Anderson, Heather (June 2014). "Amphibious Architecture: Living with a Rising Bay". California Polytechnic State University, San Luis Obispo. Retrieved 2021-08-09.
  6. ^ a b c d Baxter, R. Scott; Allen, Rebecca; Hylkema, Mark G. (August 2007). "Cooley Landing: Cultural Resource Inventory and Assessment" (PDF). Palo Alto Online. City of East Palo Alto. Archived (PDF) from the original on 2021-04-22. Retrieved 2021-07-06.
  7. ^ a b c Cargill. "Virtual Tour". Archived from the original on 2008-09-07. Retrieved 2021-07-17.
  8. ^ a b Philips, Wendy (2002-07-21). "Dredger sculpting Hayward wetlands". Oakland Tribune.
  9. ^ "'Spy in Sky' Check on Bay Fill". Oakland Tribune. Oakland, California. 1972-06-05. p. 19.
  10. ^ Krause, John (2005). "2005 Self-Monitoring Report: Baumberg Complex – Hayward, California, Eden Landing Ecological Reserve" (PDF). California Department of Fish and Game.
  11. ^ a b c d San Francisco Bay Conservation and Development Commission (2020-12-18). "BCDC PERMIT NO. 2003.007.03" (PDF). California Department of Fish and Wildlife.
  12. ^ Krist, John (2002-07-21). "Restoration of wetlands will take money, time". Ventura County Star.
  13. ^ Siegel, Stuart W.; Bachand, Philip A.M. (2002). "Feasibility Analysis: South Bay Salt Pond Restoration, San Francisco Estuary, California" (PDF). Wetlands and Water Resources. Archived (PDF) from the original on 2021-07-09. Retrieved 2021-07-06.
  14. ^ U.S. Fish & Wildlife Service (July 2019). "Don Edwards San Francisco Bay National Wildlife Refuge: 2019 -2020 Waterfowl Hunting Regulations" (PDF). Retrieved 2021-08-09.
  15. ^ Philip Williams & Associates, Ltd. (2005). "Flood Management and Infrastructure Existing Conditions Report" (PDF). South Bay Restoration.

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