MARQUETTE - A sinkhole was discovered Tuesday on the concrete bulkhead at Mattson Lower Harbor Park.
The sinkhole, about the size of a manhole cover and about 1.5 feet deep, was barricaded off by city officials who said they will fill it in and pave over it as soon as possible.
City manager Bill Vajda said the sinkhole was caused by soil erosion underneath the concrete.
"It's not an uncommon thing. They happen from time to time. Just remember that the whole park is built over the water. It's not a natural land form. Essentially the under-structure looks a lot like pilings with coffer dams around them," he said.
He said the structure for the vast majority of the park is fundamentally sound. However at times water will wash out soil underneath the concrete bulkhead.
"Even though these coffer dams sit really, really tightly together there's still enough room between them that water can work its way in there and, when it does, it eventually washes out small particulate matter and this type of thing can happen," he said.
The area that the 22-acre park sits on used to be part of the Lower Harbor. When Marquette was first settled, fishermen built shanties at the base of the bluff - near where Lakeshore Boulevard is now - and moored their boats offshore. In the mid 1800s railroads and iron companies began developing the harbor when iron ore was discovered in Negaunee.
By 1885 there were 10 separate cargo docks along the harbor, including three pocket docks for iron ore. The Grace Furnace was built in the park area in 1872 for the Lake Superior Iron Company. Slag was used to fill in part of the harbor so ships could unload coal and take on pig iron from the furnace. The furnace building was destroyed by fire in 1895, but the area was still used for coal and iron loading.
In 1929, the remainder of the park area was filled in to provide a base for the newly-built Spear and Sons coal dock. A mainstay of the harbor landscape for decades, the coal dock stopped operations in 1975, after the Upper Harbor became the main coal and iron ore dock in Marquette.
George Spear offered the dock to the city of Marquette in his will, in which he wrote he hoped the area could be used for recreational purposes. The city bought the property in 1977, and began making plans to use it for just that. Basic cleanup and landscaping was done in 1981, but the funds to rehabilitate the former industrial yard were lacking.
Local businessman Ellwood Mattson then stepped up to raise more than $500,000 in funds to get the park under way, and in 1989 it was dedicated in his name in recognition of his efforts.
Christopher Diem can be reached at 906-228-2500, ext. 242.
