Seminary Hill cache Traditional Geocache

And now a little history of this ill-fated hill.

Location: Within City of Centralia, on slope of Seminary Hill

Description: After two years of the worst drought the state had ever seen, the city of Centralia decided in 1914, to build 2 water reservoirs. The project was doomed from the start. The city council decided on a steep hill behind the city. The only problem was it was home to a Baptist Seminary. By April the Seminary was ordered closed by the city. That same month the Mayor, and city council were told that the Seminary students, and elders were going to lock themselves inside the Seminary to prevent work on the project. This was information they would never tell anyone. On April 19th the Seminary and surrounding buildings were destroyed. When workers begin removing the debris a week later, they were horrified when they unearthed nineteen bodies. Swept under the carpet as a quote "terrible misfortune", work continued. But the tragedy didn't stop there. Seminary Hill Facility consisted of two water supply storage reservoirs. Reservoir #3, constructed in 1915, contained about 3.5 million gallons of water, and cost the lives of two construction workers who were killed when a support line to the concrete forms broke. Reservoir #4 was constructed in 1926, and contained about 5 million gallons. As with Reservoir #3 there were more deaths. Reportedly The General Contractor was in a bitter dispute with 3 city Engineers over the issue of what to use as "fill" under Reservoir #4. On April 19, 1926 with work almost completed, the 3 city Engineers were killed when a high tension steel cable broke severing them all waist high. The cause was never determined. Both reservoirs were 20 feet deep with 1H:1V side slopes, and were constructed by cut and fill methods into the steep hillside. With the exception of the west side of the reservoirs, the impoundments lie below original natural ground. The embankments forming the west side of the reservoirs were constructed by pushing excavation spoils out onto the hill slope. The reservoirs were lined with unreinforced concrete, with copper strips at panel seams to minimize leakage. An underdrain system was provided beneath the reservoir floors to collect leakage. The reservoirs had repeated problems with leakage over the years, and a number of different repair schemes were implemented over the life of the project to minimize leakage through the panel seals.

Date of Failure: April 19, 1991

Cause of Failure: The failure occurred without warning. Reportedly, Reservoir #3 was evacuated in 3 minutes, with a peak channel discharge of 2500 cfs. Reservoir #3 failed first, causing the break of the service and drain lines for Reservoir #4. The 5 million gallons contained in Reservoir #4 drained for several hours after the failure. The failure was caused by a massive landslide in the siltstone rock formation that underlies the reservoirs. The cause of the landslide was likely due to increased seepage into the rock foundation through continued deterioration of concrete panel seams, and a 2 foot raise in the reservoir pool elevation after holding it down for the previous year. Interestingly, the reservoirs had been drained and cleaned in August, and apparently no unusual conditions were noted. However, the cleaning crews did not document their inspections of the seams. Further, the city did not routinely inspect the underdrain outfall (which was in a deep manhole) to see if seepage was increasing or decreasing. Judging from the portion of the underdrain pipe exposed by the failure, the underdrains may have been clogged with fines, significantly restricting their ability to discharge seepage. This, in turn, may have led to increased seepage into the siltstone foundation.

Damage Caused: The reservoirs were located on a steep hill above the city of Centralia. The flood first passed through a park in a ravine then discharged into a crowded neighborhood, causing appreciable damage. Twenty homes were knocked off their foundations and destroyed. Several other homes were severely damaged by the water and mud flow. Many other homes had silt and mud deposited in their yards. Tragically, 11 lives were lost in this failure. This may be attributed to the fact that the failure occurred at 04:19 p.m. on a Sunday afternoon, when children were outside. A Boy Scout Troop was clearing debris in the ravine at the time of the failure; unfortunately none were able to scramble out of the way of the flood wave. Financial and emotional damages from the failure were significant, and as damages to the neighborhood totaled over 33 million dollars. In addition, the City lost much of its online storage for several months, and replacement of the reservoirs was never completed. The area has since been turned into the Seminary Hill Natural Area. But few of the area residents ever go there. Some tell tales of children screaming in the night. Some have even reported seeing men walking in the tress, dressed as Clergymen.