Soil is made up of a number of Earth's natural elements – including air, water, rock, organic matter and living soil creatures. When soil is needed in large quantities (such as building a park) fill dirt and mulch are often incorporated with the soil. This fill dirt is often comprised of sandy, silty clay material with gravel and can also include varying amounts of mulch consisting of leaves, twigs, and ground-up tree parts (the fill dirt).

When Highlands' Park was created, mulch in the fill dirt began to naturally decay and decompose. The resulting byproduct of this decomposition is a temporary spike in gases in the soil beneath the park. Our experts have determined this to be natural gas (methane and carbon dioxide), which forms when organic matter (leaves and tree parts) are decaying in a space where there is very little air. As you may know, methane is also the principal component of the natural gas we use to heat our homes. Unlike at the park where the source of the methane is degrading leaves and tree parts, methane also is generated from animal decomposition and manure, coal mining, oil and natural gas production, rice cultivation and the degradation of garbage in landfills.

As a precautionary measure, we're monitoring the soil monthly and have worked with nearby homeowners to place natural gas testing devices in their homes.

From time to time, you may see our experts out at the park testing the soil. This is a step we're taking to make sure the natural gas continues to dissipate.