Bettendorf borrows much of Davenport stormwater rules but topsoil standards don't make initial drafts

Much of Bettendorf's proposed new stormwater management ordinance is based on similar regulations put in place by Davenport two years ago.

But despite the wholesale borrowing of Davenport's stormwater ordinance language, one key section – requiring developers to amend new residential lots to absorb rainfall and provide homeowners with healthy organic topsoil – never made it into the two initial drafts circulated by Bettendorf city staff to city council members.

Why the soil infiltration standards for new residential developments went "missing" from the Davenport ordinance to the Bettendorf stormwater draft rules isn't clear.

Bettendorf's City Administrator Decker Ploehn has refused to say why staff did not include the topsoil requirement in the stormwater drafts presented to aldermen.

"We have not finished our recommendations to the council," Ploehn responded to an email asking about residential lot infiltration standards. "We are in an input-seeking mode for others to comment on what was drafted."

Davenport's stormwater management ordinance does not require a strict 4-inch topsoil rule for new residential homes, but sets infiltration standards which assure the topsoil on new home lots is permeable with sufficient organic matter to soak up rainfall and support plant growth. If topsoil on the lot is insufficient to meet the infiltration standard, developers must scour the clay subsoil and add organic material in order to increase absorption of rainfall.

Bettendorf's draft ordinance outlines a list of methods for developers to utilize to retain rainfall on lots and requires developers to retain topsoil initially on the property for spreading back on the property once construction is complete.

However, there are no infiltration standards or assurance to homebuyers the lot soil will be able to soak up rainfall or provide sufficient organic material to sustain plant growth. And, there is no post-construction inspection required of new residential lots to even determine if the existing topsoil is redistributed over the lot.

Requiring developers to keep the original topsoil on each building site is an improvement from the current ordinance, which has no requirement on homebuilders to keep or amend the topsoil. Many scrape off the topsoil and sell it, placing sod on top of compacted, clay subsoil with poor infiltration.

A 4-inch topsoil requirement of the Iowa Environmental Council was gutted last year under pressure from Des Moines developers. Stormwater quality advocates opposed elimination of the topsoil requirement and several communities, including Cedar Rapids and Clive, have sought to put in place infiltration standards to assure rainfall can soak into the topsoil and prevent runoff from each new residential lot.

Cedar Rapids is still weighing the topsoil issue. Clive was on the verge of establishing a similar infiltration requirement for new developments, but the city council voted down the mayor and staff recommendation under strong lobbying by builders.

In Bettendorf, the idea of a topsoil infiltration standard didn't even make it out of the gate in the two draft ordinance updates given aldermen in recent months.

Public works officials say they weren't pressured by homebuilders before crafting the stormwater management draft, and only recently, on April 19, met with the area homebuilders group.

Public Works Director Brian Schmidt said homebuilder concerns at that meeting centered around "new permit fees, drainage through stormwater easements, as-built surveys, when to submit drainage reports, buffer language, and grading of individual lots."

In Davenport, the new infiltration standards for new residential lots passed with little controversy, and officials there say the new standards have been implemented as new developments are approved.

Not only does the Davenport stormwater ordinance require retention of the topsoil on the lot, but sets a soil quality standard with a minimum rate of 5 percent organic matter and a pH from 6.0 to 8.0.

"Healthy soil provides important stormwater management functions including efficient water infiltration and storage, adsorption of excess nutrients, filtration of sediments, biological decomposition of pollutants, and moderation of peak stream flows and temperatures," according to the Davenport stormwater ordinance. "In addition, healthy soils support vigorous plant growth which intercepts rainfall, reducing runoff by increasing evaporation and transpiration.

"Urbanization and development severely diminish a soil’s capacity to absorb, filter and store rainwater. Common development practices including clearing and removal of topsoil during grading, compaction of remaining soil, and planting into unimproved soil or poor quality imported topsoil, produce unhealthy plants and lawns that require excessive fertilizers and pesticides which can lead to polluted stormwater runoff," the Davenport stormwater ordinance states.

CLICK HERE to download a copy of Davenport's stormwater ordinance adopted in 2014.

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