NORTH DAKOTA STATE UNIVERSITY - FARGO, N D


DEPARTMENT OF GEOSCIENCES, NDSU

TOILS ON WEAK SOILS:

A PHOTO-ESSAY ON THE CONSTRUCTION OF THE STOCKWOOD FILL (1906 - 1909),
PART III:

THE ARCHWAY



"The arch has not shown any settlement lately . . . but it
is just hanging on a balance."

Letter from F.L. Birdsall to W.C. Smith, November 1,1908.


[Completed archway]

View, facing to the south, of the completed concrete archway near station #1262, Stockwood Fill, ca. fall, 1906. The gentleman at the center is probably S.A. McCoy.

S.P. Wange photo, © Clay County Hist.Soc.

Smith and other N.P. officials were horrified to read this latest news from Birdsall, for just to the southwest of Stockwood Depot was their $11,000 archway. A "test pit" here had shown 10 ft of quicksand overlying the 63 ft of soft clay. Birdsall's superiors reluctantly agreed to let him fill in the permanent bridge, but they ordered him to keep the fill away from the archway until a wide "mattress" could be completed around the concrete structure.

Workers extending the "mattress" of fill near archway, Stockwood Fill, late summer, 1909.

A.F. Rusten photo, © Clay County Hist.Soc.

[Building a mattress near archway]

The photographs (above and below) both date from this time. The views are from the north facing toward the southwest, with the concrete archway barely visible below and to the right of a sharp hump in the railroad tracks. The hump itself coincides with the only remaining stretch of unburied trestle, and the elevation of its peak is the last artifact of the intended (design) grade. The embankment to the east and west of this point shows significant settlement to elevations many feet below design grade. The zone of broken ground in the foreground represents a compressional ridge.

[Compressional ridges near archway]

Compressional ridge near archway, ca. June, 1909. Archway (still unburied) barely visible at right-center of photo below "hump" in tracks. Note that trestle to either side of archway has been filled, with the filling accompanied by sagging and associated compression.

A.F. Rusten photo, © Clay County Hist.Soc.

As filling progressed toward the region of the archway, the ground cracked in advance of dumping. Despite the decision to withhold filling of the archway, the stresses of embankment settling nonetheless reached this structure. By 1908, small cracks had begun to develop in the concrete, and these increased in size during the spring of 1909. In July, 1909, as fill loading of the archway's trestle was nearly completed, the embankment here underwent severe settlement. The archway, stressed at its center by the downward pressures of embankment settlement and at its openings by the upward pressures of rising compressional ridges, broke at its center. The embankment settlement and flanking compressional ridge are visible in the photograph below, taken with the photographer facing northwestward toward the archway's south entrance.

Collapsed archway, Stockwood Fill, ca. fall, 1909.

A.F. Rusten photo, © Clay County Hist.Soc.

[Collapsed archway]

The archway was abandoned as a project, and over the years it continued to sink until much or all of it sunk below the surface. (The top part of it was encountered in the late 1950's during construction of the Minnesota Highway 9 underpass, but much of the archway still lies below the present highway surface).

[Collapsed archway]

View inside collapsed archway, ca. winter, 1910.

A.F. Rusten photo, © Clay County Hist.Soc.

CONTINUE



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