Article by Elena Ferrarin
Communications Coordinator
Northbrook Park District
The Process
At the end of fall, Northbrook Park District staff prepare the clay areas of our ballfields (the “skinned infields”) for winter. The goal is to ensure excess water drains and dries out, so the fields are ready for safe use in the spring.
This is a delicate process because clay must be treated in a very specific way.
Staff top-dress the infields with a layer of high-temperature processed calcined clay. This top layer helps pull moisture upward from the deeper clay, preventing the infield from becoming too dusty and creating the proper playing surface for spring.
Over the winter, freezing, thawing and rainfall shift the clay. Staff repair this by filling in low areas, re-grading the slope (“pitch”), and rolling and packing the clay to make it firm and even. This allows excess water to flow from clay surfaces to turf areas, creating even moisture distribution and preventing water from forming puddles.
An even, compacted surface is critical for quick drying once spring arrives.
The Problem
When people walk on a wet infield, their footprints compress the clay and create small depressions that trap water, which soaks into the clay. The wet clay compacts further, forming a harder, deeper puddle area that cannot be quickly fixed.
By spring, these spots can be so damaged that field openings must be delayed.
Unfortunately, sometimes well-meaning field users compound the issue.
Simply scraping clay off the field’s surface doesn’t fix the wet areas. Instead, it worsens the problem, because removing the top layer also removes the specially prepared surface that helps the field dry.
Additionally, pushing wet clay into the grass around the infield creates raised edges (“lips”) that can become a trip hazard for players and cause balls to take dangerous hops. Clay on the grass also smothers the turf, causing bare or unhealthy patches.
Over time, repeated clay buildup creates a higher turf line, changing the grade of the field, reducing surface drainage and causing even more long-term issues.
The Solution
Just because the weather might feel like spring, our ballfields might not be ready for activity through the end of March (or later depending on conditions).
The Northbrook Park District kindly asks that people keep off the fields until they officially open, so staff can perform the proper work to ensure safer play and better field conditions for everyone.