Zoo Achieves Big Savings with Wastewater System

Baton Rouge Facility Uses
Innovative Treatment Method

Photographs by David Humphreys
Animation by John Carambat

Savannah, an elephant at the Greater Baton Rouge Zoo, is cleaned and cooled off as handler Karen Quebedeaux hoses her down. Click for a full size photo (79K).

IN AN ENVIRONMENTALLY FRIENDLY setting, the Greater Baton Rouge Zoo is operating cost-efficiently with an environmentally innovative wastewater treatment system. The results speak dollars and cents, as the zoo saves an estimated $200,000 annually in sewer user charges.

Completed in 1992, the system uses an "artificial marsh/rock-reed filter" to treat the zoo's wastewater instead of sending it into the Baton Rouge/East Baton Rouge Parish system for treatment.

The Baton Rouge Recreation and Parks Commission (BREC), which operates the zoo, authorized the innovative approach in 1991 based on the following benefits:

• Sewer user fee charges paid to the City/Parish would be completely eliminated.
• Construction of the proposed system would pay for itself in less than four years, with the facility projected to have a minimal operating cost.
• The history of the zoo's sewage effluent chemistry sampling showed that the wastewater discharge consistently met secondary treatment standards and would adapt easily to an advanced treatment process.
• Zoo Director George Felton, who served until his retirement in 1995, visualized the proposed artificial marsh as both a potential educational facility and a zoo exhibit demonstrating an efficient, inexpensive, natural method of sewage treatment. The treatment system would be all natural, with no mechanical components or chemical additions, and was expected to draw waterfowl and other forms of wildlife. This would create an exhibit showing animals native to the Baton Rouge area.
• The proposed method of treatment was innovative but was advocated and promoted by Region VI officials of the U.S. Environmental Protection Agency (EPA).
• The utilization of this alternative "wetlands-oriented" system would be the first known application of its use successfully treating a zoo's wastewater effluent to meet stringent EPA and state discharge limitations.

In 1990, the Greater Baton Rouge Zoo was paying roughly $150,000 a year in sewer user fees to the City/ Parish for treatment of its wastewater discharge. BREC Superintendent Eugene Young, who recognized that this charge would only increase with time, retained the local engineering firm of Simmons J. Barry & Associates to assist BREC in investigating options to reduce the service charge.

After an in-depth preliminary engineering report, BREC chose to eliminate the sewer user fee entirely by proceeding with construction of the artificial marsh/rock-reed filter. It was designed to treat an estimated 400,000 gallons of average daily flow generated by the 145-acre zoo site with its 1,100 birds, reptiles, and mammals.

The wastewater to be treated would consist primarily of effluent from the zoo's septic tanks, serving about a 30,000 person monthly attendance; wash-down from animal cages; animal pool dumpings; and storm-water runoff from specific animal cages that must be treated according to national zoo regulations.

The proposed artificial marsh site was a 2.2-acre location in the very interior of the zoo's boundaries. The existing terrain would require an extensive topographic survey, since it was known to have significant elevation differences. Moreover, it was tightly wooded with dense undergrowth, making this a potentially costly survey.

To expedite the surveying of the grounds, Felton had his elephant keeper direct the zoo's elephants in a maneuver to clear the area. The elephants trampled the underbrush and knocked down small trees to open up lines of sight for the surveyors. This is believed to be the first use of elephants in America to assist in a land survey.

An artificial marsh/rock-reed filter system operates most efficiently utilizing a large basin or pond for wastewater and storm-water storage and preliminary treatment, as well as a natural filter. The filter consists of a shallow basin filled with rock on which plants - such as bulrush, reed, and cattails - are grown. The plant roots are presumed to provide additional treatment by taking some nutrients from the wastewater and by introducing oxygen into the wastewater flow.

In the zoo's case, the pond is a 50,000-gallon equalization basin that was constructed before the rock-reed filter was installed. Prior to installation of the system, rainfall and runoff from 6.4 acres of animal pen grounds were collected by a moat system that discharged directly to the zoo's sewer collection system.

A one-inch to three-inch rainfall event over 24 hours could generate 150,000 to 500,000 gallons of rainfall induced flow entering the moat system in addition to the normal water use. The equalization basin provides a constant average flow by eliminating peaks in the daily flow conditions. Excessive wet-weather rainfall conditions would also utilize the estimated 500,000 to 750,000 gallons of storage capacity in the existing moat system that separates the animal cages from the public.

The total artificial marsh/rock-reed filter system was constructed at a cost under $500,000. However, during the first week of start-up in 1992, a totally unforeseen problem was revealed.

	The animal-solids primary settling tank (above) is an innovative feature of the Greater Baton Rouge Zoo. Click for a full size photo (57K).

A dense mass of solids, up to two feet deep, not only settled out into the equalization basin, but also flowed into the marsh, plugging and coating the rock media. These solids had not shown up in any prior chemistry sampling history and were not known to exist by zoo personnel.

Part of the zookeeper's normal operating procedures is to shovel and scoop up all animal solid waste out of pens and cages on a daily basis prior to performing any wash-down procedures. It was, therefore, believed by all involved in the design process that there was minimal animal solid waste entering the sewer system until it became evident in the start-up process that there was a solids problem.

Investigation by the zoo staff concluded that the elephants, hippos, tapirs, and other assorted creatures defecated in the cooling ponds, pits, and tanks. These facilities are routinely drained and were found to release an estimated volume of 20 55-gallon drums per week of dewatered animal waste product consisting of primarily undigested hay and feed.

The solution to this problem was construction of an innovative animal solids primary settling tank prior to the equalization basin by in-house BREC crews. Again, no mechanical or electrical items were installed that would require maintenance by the zoo staff. It is planned for the dewatered animal solid waste to be used as a fertilizer for gardens throughout the zoo and park system, upon DEQ approval.

The system's effluent holding pond was constructed to have a natural appearance and is well stocked with goldfish, catfish, and other carp. "It has attracted wood ducks, egrets, and other birds, along with nutria, muskrat, and reptiles, creating the hoped-for waterfowl and wildlife exhibit potential for the general public," according to Felton.

Among the elements of the Greater Baton Rouge Zoo's wastewater treatment system are the effluent holding pond (left - Click for a full size photo - 114K), which contains such species as goldfish and catfish, and the rock media (right - Click for a full size photo - 108K), a natural filter dotted with plants.

Bill Palmer, BREC Director of Planning and Engineering, says the estimated $200,000 saved annually by the zoo in sewer fee charges goes back to the zoo for its upkeep and capital improvement programs. "This wastewater treatment facility is saving the taxpayers money and allowing for additional improvements to the zoo facility to service its annual 300,000 visitors," says Palmer.

Both BREC and its engineering consultant, Simmons J. Barry & Associates, have received numerous inquiries about this treatment process from zoos throughout the country. BREC, which was recently ranked as the number one recreation program in the nation, again finds itself in a leadership position that should make the citizens of Baton Rouge proud.