A Decade of Recovery
by Rita Robison, Senior Editor;Serial Information: Civil Engineering—ASCE, 1991, Vol. 61, Issue 7, Pg. 40-43
Document Type: Feature article
Abstract:
The Outstanding Civil Engineering Achievement Award for 1991 went not to a single project, but to an entire decade's effort by the Portland (Ore.) District of the U.S. Army Corps of Engineers. Their response to the eruption of Mount St. Helens in May 1980 entailed planning under pressure, designing against unknowns and devising innovative solutions for approval by numerous other federal, state and local agencies, plus an anxious public. The Corps' emergency response�salvaging lives and property�evolved into long term planning for permanent solutions that were in place a decade later. Two major projects mark the effort. One is an outlet tunnel driven 8,460 ft through rock to tap Spirit Lake, which had been enlarged by an unstable debris dam. The tunnel prevents major flooding by holding the lake to a safe level. To prevent sediment from choking local rivers, the Corps dammed a stream with a three-part structure designed not to stop water but to trap sediment: an embankment dam, outlet works and abutment spillway. Ports in the outlet works will be closed off as sediment rises within it over 50 years, when the river will be diverted entirely through the spillway. Of the $1 billion spent during the decade, nearly half went for Corps work; part of the rest is reflected in the new National Volcanic Monument, for which the Corps drew up the comprehensive plan.
Subject Headings: Spillways | Sediment | Embankment dams | Tunnels | Rivers and streams | Project management | Lakes
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