PUBLIC WATER SUPPLY SYSTEM

The city of Higginsville has used surface water supplies for drinking water since 1925. Groundwater sources are unreliable, at best, in this area of the state. The Higginsville water treatment plant serves water users outside of the incorporated area. Wholesale customers include the town of Corder, which wholesales to Alma, the town of Mayview, and the Lafayette - Johnson - Saline Public Water Supply District Number 2 (PWSD#2). Higginsville supplies 62 percent of all the water purchased by PWSD#2. (Refer to Appendix C, Lafayette - Johnson - Saline Public Water Supply District Number 2 Service Area.)

-- Table 5 --
Higginsville Lake Water Supply Users *

Provider	Service Connections	People Served
Higginsville	1,930	4,700
PWSD#2 **	1,259	3,150
Corder	235	515
Alma	248	445
Mayview	143	430

* Census of Missouri Public Water Systems 1991, DNR, Division of Environmental
Quality, Public Drinking Water Program
** Dennis Knipmeyer, Lafayette-Johnson-Saline Consolidated Public Water Supply
District #2

The Higginsville Reservoir system consists of approximately 194 surface-acres of water. There are two lakes in series that make up the lake supply. The upper lake dam was constructed in 1925. Because it is located immediately upstream of the lower lake it primarily serves as a settling basin. The lower lake dam was constructed in 1949 and is the location of the intake tower for the treatment plant and public water supply. Drought conditions in the late 1970s led to re-evaluation of the lake supply and the city constructed a pump intake in the Missouri River to provide additional water. The twelve-inch transmission line delivers raw river water into the upper lake at 1,250 gallons per minute (gpm). This pumping process is initiated when the lower lake surface drops to three feet below normal pool.

The water plant was constructed in 1987. It has a design flow rate capacity of 2.5 million gallons per day (Mgd). The treatment process is operated on a 2.0 Mgd flow rate for approximately 11 hours per day, producing an average daily output of 900,000 gallons.

Major processes in the treatment train include:

	Raw Water: Water is injected with chlorine dioxide to destroy bacteria and algae.
	Primary Settling Basins: A coagulant (alum) is added in a flash mixer just before the flocculation chamber for removal of colloidal sediment. Powdered activated carbon (PAC) is then added at the flocculating basin for synthetic organic compound (SOC) removal along with taste and odor concerns.
	Secondary Settling Basins: Both lime and fluoride are added ahead of flocculation. The lime is used for stabilization and further clarification. Fluoridation is added for dental health.
	Filtration: Water flows by gravity from the secondary settling basin through filter beds of anthracite and sand. The plant has four filter beds through which the flow is split.
	Disinfectant: Chlorine is used as the primary disinfectant and is usually added both upstream and downstream of the filtration process. The lake is treated with copper sulfate as needed, three to five times per year, to reduce taste and odor problems created by algae.
	Finished Water: Finished water is first stored in a 500,000 gallon clearweu adjacent to the treatment plant. From there the water is pumped throughout the system with additional storage and pressure maintained in three elevated facilities. There are 700,000 gallons of additional storage.

-- Figure 10 --
Higginsville Water Treatment Plant
-- Treatment Train Schematic --

Plans are being made to alter the treatment process for SOC (synthetic organic compound) removal. A proposal has been prepared to replace the anthracite caps on two of the filters with granular activated carbon (GAC). This will be used in place of the current PAC additive. There are a number of operating parameters that will be affected by this change. Dr. Robert Segar, University of Missouri - Columbia, is conducting a study to monitor the performance of this treatment process. (Segar, 1996)

Water supply capacity is not a concern at this time since the plant has the capability to pump water from the Missouri River at the rate of 1.8 Mgd. However, this pumping arrangement was not designed to be used on a daily water supply basis. The operation of this system requires continuous monitoring and increases the cost of water treatment. This installation could be used more efficiently in order to improve future water demand increases. At the present some annual use of the pumping facility can be expected, even in a year with normal precipitation. Pumping can make up for evaporation and seepage loses during dry, late summer months.

Public water supply users identified potential contamination of the lake by accidental spills as a concern. A factor in the clean up of such an event is the amount of time necessary to exchange the volume of tainted water in the reservoir with new, uncontaminated water, from either runoff or pumping. This is important in removing contaminants from the water supply that are not biologically degraded. The term used to describe this exchange rate is hydraulic residence time. It is the estimated time that it takes for the watershed to deliver enough water to completely replace the storage capacity of the reservoir.

The residence time for the Higginsville City Lake is approximately nine months. This is not a significantly high number for a water supply impoundment because the design is driven by storage capacity needs. However, if contaminants are introduced into the system their removal by dilution will take a significant length of time. As an example, to lower the concentration of a pesticide in the reservoir by one-half would take approximately 150 days of continuous pumping with the current system. This example does not include water from rainfall runoff, losses from evaporation, seepage, or consumption usage during this period and it is assumed that the water being pumped in has no concentration of the pesticide contaminants. From this analysis it seems that the development of an emergency action plan to address accidents would be a worthwhile effort.

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