Document 46: Denny Hill Regrade

O. A. Piper, “Regrading in the Seattle North District,” [c. 1910], Local Improvement District 4818. Seattle Municipal Government, Engineering Department, Local Improvement District Files, Seattle Municipal Archives, Office of the City Clerk, Control No. 2615-03, Microform,
Letters, Folder 3. pp. 2, 15-16, 33-34.

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O. A. Piper, an assistant city engineer, discusses the first Denny Hill regrade:

Regrading carried forward in the district lying south of Yesler Way, had the double purpose of securing a passageway through the ridge of Beacon Hill and of utilizing the spoil therefrom for the reclaiming of the contiguous tide-land areas.

In the district lying north of Yesler, however, spoil-disposal was a subordinate matter, the primary object being the removal of the immense mound of earth which rose to a summit near 4th Ave. and Blanchard St., familiarly known as the “Stewart Hump,” the mound as a whole being popularly known as Denny Hill.

During the last decade, from 1900 to 1910, Seattle ranks third among the larger cities of the United States with respect to rapidity of growth, being surpassed only by Los Angeles—population 119,198, increase 211.5% and Birmingham—population 132,685, increase 245.4%.

This unusually rapid growth naturally tended to complicate the engineering problem of civic improvement which, by reason of the rugged topography of the city, were already sufficiently serious; and finally, by the combined influences of rising property values and congesting business districts, forced the inauguration of what is, in many respects, the largest and boldest municipal regrade project in history.

About the middle of September 1906, the steam-shovel and dirt train equipment of the private contracts was supplemented by the installation of a hydraulic giant using water from the city mains. All these methods were, however, inadequate to the task of moving the material with the speed desired by the hotel company and a contract was let for a pumping plant to take water from the sound.

At this time, the latter part of 1906, and the early part of 1907, the railways leading into Seattle were congested with freight business, and machinery shipments were delayed at times for periods running into months. In spite of this condition, however, work on the installation of this pioneer pumping plant was rushed with all possible speed; and the motor, ‘the largest in the Northwest,’ was started on February 1, 1907.

This plant consisted of but one large unit, being an 800 h.p. motor belt connected to a four-stage turbine. This turbine was guaranteed to deliver 3500 gallons per minute against a pressure-head of 180# at the pump, or slightly more than 5,000,000 gallons per 24 hr. day. This amount will be better understood by remembering that the maximum capacity of the Seattle water system at this time as about 23,000,000 gallons per day.

“In spite of many troubles, due to haste and faulty design, this initial plant demonstrated beyond question the entire feasibility of the hydraulic method as applied to regrading in Seattle.

A glance at the various photographs, panoramic and otherwise, which accompany this report, will show the sweeping and drastic changes which this great improvement has wrought in the topography of Seattle. And these changes, involving though they do the removal of almost six million cubic yards of dirt, and the expenditure, public and private, of probably more than three millions of dollars, are already amply justified by the advantages already accruing to the district involved.

And yet these advantages, real and far-reaching though they be, are of subordinate importance to those accruing to the City as a whole. The removal of this formidable traffic-obstacle throws open to development, by reasons of the rapid expansion of the business district, an area comprised between First Avenue on the west and Lake Union on the east, and extending northerly as far as Aloha Street or beyond.

And, in addition to its provision for a business area adequate for a city of at least double our present population, the improvement of the Denny Hill district literally paves the way for the establishment of those highly important traffic-arteries which are to bring the northern districts of the city into closer communication with its commercial centers.

Perhaps it may be said that, in all three points of area of volume and of vital importance to Seattle’s future development, the Denny Hill Regrade far surpasses any previous local improvement ever attempted by this municipality.

Center for the Study of the Pacific Northwest