A Report on Archeological Investigations Within the Grand Portage Depot (21CK6), Grand Portage National Monument, Minnesota: The Kitchen Drainage Project
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While the field investigations of late September were still continuing, the National Park Service identified a Contractor to install the new drainage system. Subsequent to completion of our archeological work the Contractor received notice to proceed, initiating construction on October 16, 1989. As the supervising archeologist for the earlier research, I was called upon to monitor installation of the drain while ground disturbing activities were under way. All work requiring direct observation was complete by the end of that week (Figure 9).

Figure 9. Workers check grade of trench near the Kitchen.

Trenching began at the lakeshore on the morning of October 16, a large section of reconstructed palisade having been removed previously by the Monument staff. That particular stretch of lakeshore had been stabilized some years earlier, and trenching for the drain outlet necessarily disturbed the integrity of that system of rip-rap and filter fabric. No buried cultural deposits, however, were revealed by the initial backhoe cut.

Immediately inside the palisade line the backhoe encountered what appeared to be remains of a former septic system. Several thick-sawn boards were turned up near the ground surface, and mortared stones were exposed in the east profile of the trench (Figure 10). It was known that an early visitor facility had stood near this general location when portions of the Depot were first reconstructed some 50 years ago. Although the structure was later removed as a modern intrusion on the historic scene, associated amenities below grade were abandoned in place.

Figure 10. Mortared stones representing former septic system are exposed in trench profile near palisade.

It was near this point where the backhoe operator also intersected the existing 1975 drainage line. Having exposed that line, which was to be the main path for the new installation, the operator straddled it with his machinery and proceeded northward to the Great Hall/Kitchen area. No substantial archeological deposits were revealed by the progression upslope, though a few isolated items occasionally came to light. In each case but one, however, the artifacts were of no earlier age than the turn of the last century. The single exception was a small white clay pipestem fragment, a rather ubiquitous artifact of the fur trade period.

Careful scrutiny of the trenching operations increased as they neared the presumed location of Structure 1. Although our investigations undertaken in late September yielded no surviving evidence of that fur trade era feature, there was still reason to be concerned about the possible presence of intact remains within the direct impact zone. Inspection of the trench profiles, however, did not provide any hint that a structure ever stood at this location. Either the new drainage line must have passed through a section of the structure excavated in 1936, or the trench missed the remains of Structure 1 altogether. The latter alternative is perhaps the more probable, given the fact that the trench was excavated a few feet west of the line shown on project plans and the possibility that Structure 1 may not be precisely plotted on the Grand Portage archeological base map. Regardless, no apparent damage to that feature resulted from the 1989 drain installation.

Trenching continued past the south side of the Great Hall, at which point the alignment shifted east to ward the Kitchen. Progress was slower in this area, since the drainage conduit had to be set deeper relative to the prevailing ground surface. Further, the earth was rockier on this level bench, and the dense basal clay occurred higher in the soil column. Both geological factors offered greater resistance to the backhoe operator.

The two interceptor drains placed parallel to the north and west foundations of the Kitchen structure were designed to fall within a block excavated prior to the reconstruction. That fact notwithstanding, the width required at the top of the trench meant that some ground disturbance outside the block might occur. Thanks to the skill of the backhoe operator, however, new ground disturbance was kept to a minimum, and no cultural resources were exposed or damaged.

The east-west segment connecting the Kitchen drain elements to the downslope segment also was excavated without encountering any significant archeological remains. Only the short segment of conduit running under the Kitchen foundation to the crawlspace sump is worthy of remark, though not in reference to any cultural resources. Excavation of that trench released a large volume of water that had collected underneath the structure. Literally hundreds of gallons flooded into the trench, dramatically underscoring the need for a new drainage system.

In addition to monitoring the backhoe excavations, it was also deemed prudent to have the archeologist present while the open trenches were backfilled after installation of the conduit. It was entirely possible, of course, that a trench wall collapse during that process might expose cultural resources in adjacent areas. Those fears proved to be unfounded, however, as the backfilling took place without incident.

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Last Updated: 15-Jul-2009