SANDY DRAINAGE IMPROVEMENT COMPANY
Sandy Drainage Improvement Company is located in Multnomah County, Oregon, near Troutdale, and extends along the Columbia River between miles 119.0 and 121.5. The downstream (western) end of the district adjoins Multnomah County Drainage District No. 1 at Campbell road. The east boundary extends upstream along the left (west) bank of the Sandy River 2.5 miles to the Union Pacific Railroad Bridge. The Union Pacific Railroad forms the southern or landward boundary. The District includes 1,550 acres, consisting of the Troutdale Airport, Alcoa Aluminum, Civil Aeronautics Administration and industrial development. About 2 miles of natural waterways and drainage canals within the area cover approximately 16 acres. Ground elevations average about 6.0’ to 20 feet, NVGD 29.
CONSTRUCTION HISTORY
1915 - 1919, Sandy Drainage District was organized as a private enterprise to start construction on the levees. 1919 – 1939, 15,300 feet of levee and a pumping plant with a capacity of 7,500 gpm were constructed. The original levee was constructed to about the height of the 1876 flood level.1
1940 an 1941, the Corps of Engineers reconstructed about 2.4 miles of existing levee, and constructed about 1.2 miles of new levee, a pumping plant, and a tide box.
1948 flood, considerable seepage occurred along the levee toe. The amount of seepage water within the company and the threat of levee failure were such that the Reynolds Aluminum Metals company completely suspended operations, Evacuated its plant, and made about 600 men available for flood fighting activities. A temporary levee was constructed along the west end of the company shortly after a levee protecting Multnomah County Drainage District No. 1 failed. A sandbag levee was constructed around the aluminum plant as insurance against threatened levee failure. Also, a considerable amount of work was done along the toe of the main levee. As a result of the combined efforts of all concerned, the levees remained intact and seepage was controlled to the point where very little damage occurred.
1948 post flood, the 8,500 gpm pump originally installed by the company was reconditioned. In
1949 the company replaced the low-head pump, installed by the government in 1941, with a high head unit. The new pump has a capacity of 20,000 gpm against a 31-foot head. In addition, the aluminum company has separated the drainage from the area adjacent to its plant and has installed a new pumping plant, which discharges into a small lake between the levee and the Sandy River. The new plant, with a capacity of 9,000 gpm, raises the total installed capacity of the company to 36,500 gpm, which is considerably more than what was available during the 1948 flood.
1949, the Oregon State Highway Commission constructed a new levee section adjacent to the Columbia River Highway.
1952, a 40-inch diameter pipe was constructed over the levee into Company Lake at the Reynolds Metals site (Station 68+15).
1953 – 1954, a portion of the old low levee system was incorporated in the new cross levee between Sandy and Multnomah Drainage districts. In addition, new lateral drains and culverts along the toe of the main levee.
1954, two 42-inch culverts were installed in the pump station.
1955, the District upgraded and strengthened the levees using design documents prepared by the Corps of Engineers.
1996, the City of Troutdale funded a capital project to replace the other low head pump with a high head pump increasing pumping capacity during the 100-year flood elevation from 28,000 gpm to 41,000 gpm. The project also consisted of upgrading the electrical switch gear and feeds.1998, the single manifold discharge pipe was replaced with two HDPE pipe and siphon breakers and back flow values. The pump house and transformation was upgraded with emergency back up feeds.
2005, 4,000 linear feet of levee resurfacing was completed and the top of the entire levee rocked for equipment access.
PERTINENT DATA
Top Elevation of the levees (in feet NGVD 29)
Columbia River Levee 44.0’
Sandy River Levee 45.0’ Prelim. Peak Flood El. (in feet NGVD 29) at the Midpoint of Levee
| 10-yr | 50-yr | 100-yr | 500-yr | Levee Design Flood | | 25.4' | 28.9' | 30.3' | 34.1' | 36.2 |
Levee Freeboard (in feet NGVD 29)
Levee Design flood - 8.3’
100-year - 14.2’
Safe water level (in feet NGVD 29) East End West End Columbia River Levee *34.9’ *34.6’ *these elevations taken from NPP Publication; Drainage District Condition Study on safe water surface levels, May 1978
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