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From Gray to Green: MSD saving money with green infrastructure

by Michael Tierney

When the rain pours in Louisville, not only do streets sometimes flood, but local waterways suffer: sewers fill up, then release water and sewage into Beargrass Creek and the Ohio River.

The expenses and projects of MSD's LTCP

The expenses and projects of MSD’s LTCP

“Combined sewer overflows — these are legal, permitted points where rainwater and sewage can leave the system during rain events,” says Wesley Syndor, a senior technical services engineer at MSD and a leader in its green initiative.

MSD's LTCP

MSD’s Long Term Control Plan

MSD has developed a Long Term Control Plan (LTCP) to combat sewer overflow, and the plan will further the “gray to green” initiative, as green infrastructure has proved to be economically advantageous for MSD and its stormwater control.

Currently, there are 97 established green infrastructure projects built by MSD that cost more than $13 million.

There has already been a return on MSD’s investment, as Syndor says green infrastructure is saving MSD “about $2 million” in operational costs.

historic portland design

Design for Historic Portland, where one can expect major green initiatives

Green roofs, rain gardens, permeable pavers, tree boxes, rain barrels, infiltration galleries and other green projects are retaining 256 million gallons of stormwater annually.

The above initiatives spring from MSD’s efforts to meet the conditions of a Consent Decree with the Environmental Protection Agency designed to reduce the flow of highly polluted stormwater runoff into creeks and the Ohio River.

MSD now has the capacity to reduce stormwater overflow by 2.7 million gallons per storm event.  This lowers operational costs and should ultimately reduce sewer service charges for rate payers.

The Louisville Metro Housing Authority on 801 Vine St. is another success story for MSD and green infrastructure spending.

The green roof’s life expectancy is twice as long as traditional roofing. Thus, over the long haul — a 40-year period — it’s equivalent to the cost of two traditional roofs, but provides markedly better results.

According to the Housing Authority, their recently installed 16,800-square-foot green roof produces the following benefits: 26 percent heat loss reduction, 95 percent heat gain reduction, 75 percent decrease in stormwater runoff, 76 percent cooling costs reduction, and a smaller carbon footprint.

The roof is a site to behold, with three patios, thousands of perennials, shrubs, garden beds, benches to sit on and a few buzzing bees to showcase a blossoming urban wildlife habitat. Plus, the green roof can lower noise pollution by some 50 decibels.

Aesthetics, savings and reduced carbon footprints are all incentives to go green.

You can get paid to go green by MSD as well. Of the $13 million MSD spent on green infrastructure, $4 million went to businesses and private property owners who used MSD’s Green Incentives program.

“It’s been hugely successful in creating a driver for private properties to go green with stormwater controls,” Snydor says. (More details about the incentives program at www.msdlouky.org.)

uofl flooding

It’s easy to see why U of L was willing to invest in stormwater overflow control initiatives

The University of Louisville has invested “millions” in green infrastructure, according to Syndor, in order to reduce combined sewer overflow, flooding, and property damage.

The maxim “an ounce of prevention is worth a pound of cure” applies to green projects, as they are not always economically feasible. Thus engineers utilize hydraulic modeling that consider water retention, flow and other variables before construction. “We believe that where modeling shows that green is cost effective, risk is minimized by using natural systems like rain gardens or bioswales to treat rainwater where it falls,” Syndor says.

The fact that the MSD lists 23 new projects for Louisville is not widely known. Most utilize water basins to store and treat polluted stormwater rather than letting it flow raw into Beargrass Creek and the Ohio River.

Yet, four projects will have green components, including one green water basin project (which cost $896,000) located near Story Avenue and Spring Street.

The design for the Story Avenue and Spring Street Water basin

The design for the Story Avenue and Spring Street Water basin

Louisville still has a long way to go compared to greener cities like Portland, Ore. and Chicago, Ill., where green roofs, rain gardens and other ecological designs that are cost-efficient, environmentally friendly, and aesthetically pleasing are commonplace.

The Chicago Bulls new arena will future a massive green roof, something the YUM! Center might have considered.

For (a lot) more information on local green projects or ideas about what you can do, check out the 250-page Green Infrastructure Manual.

And next time you’re downtown, check out MSD’s very own rain garden at their main office on 700 W. Liberty St.

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