14 area cities to confer on phosphorus removal

by Karen E. Culp

SBJ Staff

The Missouri Department of Natural Resources will hold a meeting of 14 southwest Missouri municipalities Aug. 26 to discuss watershed issues, particularly with regard to Table Rock Lake.

Bruce Martin, regional director of the division of environmental quality for the DNR, said the meeting is being held to discuss changing conditions in the lake, and that the most probable result of the discussions will be the formulation of a phosphorus regulation rule for the lake.

14 communities invited.

The 14 communities invited include Springfield. Martin said the department wants to get as much discussion as it can on the matter, because a phosphorus rule for Table Rock Lake will mean increased costs for the municipalities that will have to limit their phosphorus output. Once a phosphorus rule is introduced, it will take about a year for the rule to be put into effect.

"The purpose of the meeting is to hear from these communities what their equipment is and what they are capable of doing with regard to phosphorus removal. We don't want to ignore the economic impact of such a decision," Martin said.

Taneycomo Lake already has a phosphorus limit in place, Martin said.

Cost to cities.

If a regulation for Table Rock Lake is imposed, municipalities will recoup the costs for whatever phosphorus-removing equipment they need through user fees, Martin said. The cities will have some one-time costs, as well as ongoing, operational costs associated with the equipment.

There are two different levels of phosphorus that might be maintained in the lake if the levels are to be limited, Martin said. One suggestion is that the phosphorus be limited to a level of .5 milligrams per liter, the other is that the limit be 1 milligram per liter.

Martin said there are two types of removal systems: a biological process will achieve the 1 milligram per liter rate while a chemical filtration process will achieve the .5 milligram per liter rate.

The chemical process is one in which chemical polymers are added to the process and a precipitate, or solid, is created. The solid is then used in land applications, carefully, so that it is taken up by plants and does not run off into another water supply, Martin said.

"What municipalities will have to consider also is that there are one-time capital expenditures, but there are also continuous costs associated with these systems," Martin said.

Some phosphorus is removed through the normal wastewater treatment process, but without the necessary removal equipment, about half of the phosphorus in the wastewater supply passes through and gets into streams.

Overgrowth of algae.

Algae feeds on the phosphorus, which is a nutrient to it, and too much algae growth can be bad for a water supply's ecological system.

"There are two different schools of thought on this. Fishermen have said that fishing is very good in the areas where there is a lot of algae, but too much algae can cause the oxygen to lag in a water supply because algae can consume too much oxygen at night. There are a variety of people with a variety of opinions," Martin said.

Springfield's plan.

Springfield is already working on removing phosphorus to the 1 milligram per liter level in about 30 percent of its wastewater flow, said Bob Schaefer, assistant director of Public Works.

The city has suggested a two-phase program for getting removal equipment for its entire plant but only has a plan for phase I. Four basins will be retrofitted by the end of the year in order to remove phosphorus from 30 percent of the wastewater.

Phase II of the program would deal with the older part of the plant, and the city is conducting a modeling study to determine the best approach to removing phosphorus in that part of the plant.

"The older portion of the plant has a pure oxygen removal system. We have limited data on what would be the best process for that system, so we've initiated this modeling program to determine the best approach," Schaefer said.

The biological process the city is using in 30 percent of its flow will remove phosphorus to the 1 milligram per liter level, but Schaefer said the .5 milligram per liter level is a questionable suggestion.

"We would want to see data that would illustrate the need for that level of removal. Right now, we're not equipped for that, and it would take a considerable investment to get there," Schaefer said.

Both phases I and II's costs will be recovered through sewer user fees, but phase II will require financing for the up-front costs it will incur. The city has not yet determined where that financing will come from, Schaefer said.

Schaefer will attend the Aug. 26 meeting and is "happy to talk about the work we've done so far. I'm going to argue that whatever is done be done in a phased approach and that we look at what is going to be the benefit of that."

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