Committee Faces Challenges of Wastewater Capacity
By Karen Gould

Mackinac Island's zoning ordinance allows the population to more than double, but its wastewater treatment facility is at 85% capacity, with little room available for expansion unless the city is able to lease additional state park land or buys private land. For now, growth is controlled by the limited capacity of the treatment plant.

With a new sewer moratorium in place through the end of January, the job of the Mackinac Island Moratorium Committee is to make a recommendation to City Council on the future of wastewater treatment. Engineers, hired in August, say the plant is near the end of its useful life.

As committee discussions continue, they often come back to zoning allowances, and a recommendation to make changes to the ordinance may be included in the committee's report.

Expected in January, the report will define the Island's future growth as the committee seeks to find a balance between demand and preservation.

Capacity of the wastewater treatment plant is measured in residential equivalent units (REUs), with each unit equal to the water use of a family of four. An REU is also equal to the anticipated sewage treatment of 250 square feet of restaurant or 2.8 hotel rooms.

Sitting on the committee as a non-voting member, Phil Porter, director of Mackinac State Historic Parks, volunteered to prepare a general report on growth impact. The wastewater plant sits on property the city leases from the Mackinac Island State Park Commission. Expansion of the plant could require more land, unless new technology allows more efficient use of the current space.

Any growth, said Mr. Porter, affects the entire Island and its infrastructure. Estimates are that 250 to 300 new homes and condominiums could be allowed on the northwest side of Mackinac Island under the existing zoning ordinance, and commercial property could be allowed to double in size.

He concluded a report he presented to the committee September 19 with a suggestion to control growth and plan for any expansion on Mackinac Island by continuing to limit the number of REUs allocated each year.

The committee must determine a level of Island growth it feels is acceptable, he said, and once that is accomplished, it can translate that growth into an REU allocation plan.

In addition to the treatment facility site, the Mackinac Island State Park Commission has provided park land for water and sewer lines, inground electric and cable television lines, Fire Station Number 2, a one million gallon reservoir at For Holmes, 250,000 gallon reservoir at Fort Mackinac, the solid waste transfer and recycling facility at the old dump site, an Edison Sault Electric Company substation, Charter Communication cable television receiver satellite, and use of roads to transfer waste, landfill items, and recyclable material.

The engineering consultant, hired in August for $35,435, is in the process of evaluating the plant and preparing a scientific report that will examine the impact on the Island and cost to residents from making plant improvements to expanding capacity. An interim report is due in November.

The wastewater treatment plant, said Bruce Zimmerman, the city's public works director, has been added to, piecemeal, four or five times since its construction in the 1970s, in reaction to growth.

"We can't do that any more," he said.

Cost of any expansion, including land, upgrading the pumping station, tearing up roads to add larger pipes or replace failing ones, are all issues the committee will be addressing once it receives the engineering report next month.

"The decisions are huge," Mr. Zimmerman told committee members. "You have just scratched the surface."