Older homes on slow-draining clay, along a river with a long flood record.
Alma is a town of older, owner-occupied houses. Of roughly 3,820 homes inside city limits, the median was built in 1964. About 45 percent went up before 1960 and 76 percent before 1980, and around two in three occupied homes are lived in by their owners. Detached single-family houses make up about 67 percent of the stock. The downtown historic district on Superior and State Streets, listed in 2013, holds 72 structures, mostly brick. On lots that old, settled walks and heaved drive aprons are part of owning the place.
Underfoot it is mostly clay. Ithaca and Perrinton loams, two soil series first described in Gratiot County in 1975, cover about 42 percent of the ground NRCS maps in and around the city. Both formed in clayey glacial till where water moves slowly. Ithaca stays wet from October to May, with a water table 6 inches to 2 feet down, and NRCS rates its frost action high. Clay like that lifts when it freezes wet, so the compacted subbase, the gravel bedding and the control joints decide how a slab ages here.
Alma's NOAA weather station logs about 156 nights a year at or below freezing, and on roughly 102 of those days the high gets back above 32. Normal snowfall runs 39.3 inches. The Pine River brings water from the other direction. Its record crest at Alma, 12.82 feet, came on September 12, 1986. In May 2020 it reached 10.3 feet and affected roads in town, and the weather service expects basements along Downie and River Streets to take water once the river hits 9.5 feet.
Permits split at the city line. Inside Alma the city takes building permit applications, and Gratiot County's building official enforces the state code on them. Before anyone digs, Michigan's MISS DIG 811 system needs at least three business days of notice. Sidewalks and approaches in the right-of-way need a written city permit, and a home's approach must be 10 to 20 feet wide. Under the parking rule the city phased in by September 2022, driveways stay out of the front yard except in line with the approach, and side or rear yard pads must be at least 4 inches thick.
What concrete in Alma is up against
- Slabs heaving over Ithaca loam's clay subsoil, wet 6 inches to 2 feet down from October to May.
- Tired walks and drive aprons at the 45 percent of Alma homes built before 1960.
- Basement water along Downie and River Streets once the Pine River passes 9.5 feet.
- Spalled tops on new walks salted their first winter, which the city's sidewalk brochure warns against.
- Front-yard parking spots the city's parking rule now sends to a side or rear yard pad.
- Pole barn posts out in the county that must sit on concrete 42 inches below finish grade.
