By Debby Woodin

dwoodin@joplinglobe.com

Expansion projects to the tune of $35 million at Joplin’s wastewater-treatment plants would take 20 years to pay off and would raise rates for every category of user.

A consultant hired by the city, Stephen A. Yonker of Burns & McDonnell, Kansas City, provided the City Council at a meeting Monday night with some of the details of a rate study and cash-flow analysis he did on how to pay for the proposed construction.

That study recommends incremental residential rate increases totaling $6.32 per month over the first five years of the debt. Commercial and industrial customers would see increases in rates and surcharges. Those rates would be staggered depending on the size of meter service the business or industry uses, and whether they discharge solids that require extra treatment.

Nearly half of the city’s number of sewer customers — 47 percent — are residential. The plan would raise rates from the current $21.01 a month to $22.48 the first year of the increases.

In the second year, the residential rate would go to $23.60 per month. In the next three successive years, rates would be $24.78, $26.02 and $27.33, respectively.

Yonker told the council that the proposed rate increases were smaller than he first projected because the city is still paying on the debt it incurred for wastewater-treatment projects about 16 years ago.

Adding new debt to that would take a rate increase of slightly less than 10 percent a year until about 2015 to make the annual payments on both the old and new debt. Instead, Yonker revised the rate plan to begin paying the interest but not the principal on the proposed new debt while the old debt is paid off; that lowered the annual rate increases to 7 percent the first year and 5 percent the next four years.

David Hertzberg, the city’s public works director, said it would not be prudent to project rates beyond five years because the economy, inflation and other factors would influence future rates.

Hertzberg said the city staff will ask the council next month to put a measure on the August ballot seeking voter authorization to borrow the money for the project. Voter approval would be needed for obtaining a loan from a state revolving fund.

Engineers and city staff members have said work in excess of $16 million is needed at the Turkey Creek plant, and about $18 million in work is needed at the Shoal Creek plant.

Much of the work is needed to meet changes in federal environmental regulations that go into effect in 2012.

The Shoal Creek treatment plant is operating at capacity and needs expansion to handle current and future flow, the engineers have said. Currently, the plant treats 6.5 million gallons of wastewater a day. The proposed upgrades would allow it to handle up to 13 million gallons a day.

In other business, the council approved the installation of an additional 240 streetlights at various locations as part of an effort to double the number of lights in the city as promised when voters in 2006 approved a half-cent sales tax for public safety.