Bibliography on Vancouver Lake Watershed, including Burnt Bridge Creek, Flushing Channel, Lake River, and Salmon Creek |
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| Entire Bibliography (.doc format) | Summary | Title Page and Acknowledgements | Timeline | ||
| Vancouver Lake | Burnt Bridge Creek | Salmon Creek | Lake River | Related Links | |
| Bibliography 1900-50 | Bibliography 1951-60 | Bibliography 1961-70 | Bibliography 1971-80 | Bibliography 1981-90 | Bibliography 1991-Present |
Bibliography of Vancouver Lake watershed, including Burnt Bridge Creek, Flushing Channel, Lake River, and Salmon Creek
A history of restoration efforts for Vancouver Lake
Dames
& Moore. 1977. Pilot Dredge Program Vancouver Lake, Vancouver,
Washington for the Port of Vancouver.
As part of the rehabilitation program for Vancouver Lake, a Pilot Dredge Study has been conducted by Dames & Moore for the Port of Vancouver. The results of the pilot study when considered in conjunction with the Master Plan for lake rehabilitation lead to the following findings and conclusions.
Hydraulic suction dredges in the small to medium size range from 8 inches to 18 inches are considered most appropriate for the dredging of Vancouver Lake. We estimate that the average initial unit price for material dredged with hydraulic suction dredges will be less than $1.25 a cubic yard at today's prices. Compressed-air assisted dredges (Pneuma and Oozer) are feasible if equipped with vacuum assistance in filling the pumps although dredging costs will probably be higher than for hydraulic suction dredges.
Because of the shallow water conditions on the lake during much of the year, smaller dredges and shallow draft work boats will have fewer problems in mobilizing and dredging. However, medium-sized dredges with their longer pumping distances would be better able to pump from the central portion of the lake.
With the exception of limited areas of moderately stiff clay, Vancouver Lake soils are expected to be relatively easy to dredge and dredging productivity should be better than average. Even so, the dredging of approximately 10 million cubic yards of soil is a large task and one that may justify the use of more than one dredge to complete the work in less than five years.
Containment dikes for dredged material can be constructed with native soil. Only minimal compaction beyond that produced by the earth moving equipment is necessary. However, the native soil is silty and very difficult to work during wet periods. Dike construction should therefore be scheduled for the dryer months of the year. Where dikes are higher than approximately 10 feet, stage construction is recommended as being economically preferable. For dikes constructed within the lake, stage construction will be necessary to maintain adequate slope stability. When stage construction is used selectively, dedged excavated spoil material will generally be suitable to raise the dikes.
The dredged soil will initially occupy approximately 50 percent more volume in the spoil area than in the lake bottom. Gradually, however, the soil will consolidate until it occupies approximately the same or even less volume than in the lake. The rate of consolidation and soil strengthening is strongly dependent on the grain size of the soil and therefore the distance from the dredge discharge. The coarser soil, near the discharge, should "cure" within a few days or weeks. The finer deposits near the overflow weir may require approximately one year before they can support light traffic. Mechanical conditioning would greatly accelerate the rate of curing but is not generally recommended because of its cost.
Vancouver Lake sediments are generally fair to good for nonstructural fill but poor to fair for structural material. However, limited selective excavation of clean sand should provide a good fill soil for use on bathing beaches or in starter dikes. The dredged soils are suitable for agricultural use, although shallow reworking, crop management, and time will be necessary before the soils can serve as a productive growing medium.
Dredging will result in the degradation of water quality, primarily due to dissolved and suspended material recirculated to the lake with the retention pond effluent. The most significant parameters measured during the pilot dredge program include temperature, oxygen related parameters, turbidity, nutrients, and certain trace metals and pesticides.
The metals copper, zinc, and mercury and the pesticides lindane and aldrin were found in significant amounts. However, they may be associated primarily with particulates and thus not readily avialable to biota. Additional work is underway to determine the degree of biologic availability.
Because of its large size, Vancouver Lake has a significant capacity to assimilate the products of dredging. The lake would act as a large detention pond and would be effective in reducing those constituents associated with particulate matter.
Introducing flushing water to the lake during dredging would greatly reduce the levels of dredging-produced pollutants within the lake.
Dredging should result in only minor impact on Lake River north of Salmon Creek and in other bodies of water downstream from Vancouver Lake.
Various measures are recommended to minimize the impact of dredging. These include approved dredging operations, increasing retention time, using longer overflow weirs, avoiding hot-weather dredging, using air diffusers, cascading discharge flow, and using flocculants.
Water quality monitoring should be conducted during production
dredging to identify areas which might differ from those studied in the
pilot dredging program and to serve as an early warning of deterioratin
in water quliaty.
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Last modified:April 17, 2008
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