A series of hearings about top soil requirements will conclude this week in Des Moines and will result in a final ruling in June that could result in significant savings for developers and builders.

At issue is a state requirement that soil be removed, stored and reapplied at development sites so that construction lots have 4 inches of topsoil. The rule is intended to lessen the impact of storm water runoff.

The state implemented its topsoil rule in October 2012 to meet requirements of the federal Clean Water Act. The federal rule was slightly more generous for developers and builders, saying only that topsoil should be “preserved.” The state rule added the 4-inch requirement, and brought quick opposition from land developers and home builders.

The Iowa Department of Natural Resources held a hearing last week in Cedar Rapids, another one Wednesday in Davenport and will conclude the process at 1 p.m. Friday at the Wallace State Office Building in Des Moines.

Developers and builders want the rule changed to require them to preserve topsoil on site, meaning that they don’t have to repeat the multiple steps of removing soil, storing it off-site, cleaning the streets each time they move it, then return it to the site and leave it for home builders to spread the dirt on a finished construction site.

A study by Hubbell Realty Co. found that the process adds $3,500 in costs to each lot they develop and $800 to $1,200 per lot for builders.

Creighton Cox, founder of C2 Policy Advocates Inc. and a longtime policy advocate for the Greater Des Moines homebuilding industry, said the soil frequently ends up being stored in areas that would otherwise be used for bioswales and other forms of storm water detention structures.