History of Mandan's Municipal Water Treatment Plant
The Mandan water works was established in 1911, at a cost of $74,000 a steam pumping plant was erected on the bank of the Missouri River, about two miles northeast of city. The water flowed from the river by gravity through two 12-inch cast iron pipe intakes to a 40-foot round concrete well, from which it was pumped to the sedimentation basins or ponds.
This installation consisted of two sedimentation basins, having a combined capacity of about 2 million gallons per day (MGD). The pump used to draw water from the intake well having capacity of about 27,000 gallons per hour.
Outside of the natural sedimentation in this basin and the chlorination of the water before being pumped to the reservoirs, the water was not treated. From the sedimentation basins, the water was pumped through a 10-inch water main to two concrete reservoirs located at Collins Avenue and Division Street. These reservoirs had a capacity of about one-half million gallons and provided a slight additional sedimentation capacity. From these reservoirs, the water was distributed by gravity through the mains to various parts of the city.
The next 12 to 15 years. Due to the increase of population and the increase of average consumption per consumer, the plant was worked to capacity with the result that the water could not be left in the sedimentation basins long enough for any sedimentation to take place.
1928 - The pump used to draw water from the intake well was replaced by a pump having a capacity of 135,000 gallons per hour. Also the sedimentation basins were doubled by the construction of an additional basin; gates were provided in these basins, allowing only clear water to flow from basin to basin. This water still contained a trace of fine sediment. The feeding of chemicals was started, using lime, sodium aluminate, aluminum sulfate injected to the suction side of the pump, resulting in very clear water and practically free from all sediment. Also laboratory equipment was purchased for the purpose of testing and analyzing the city water supply.
1936 - A 1,000,000 gallon steel reservoir was built next to the other reservoirs on Collins Avenue, at a cost of $19,500.
1938 - The plant was remodeled to a capacity of 2 MGD. The plant consisted of intake, presedimentation, fluoridation, chemical feeding, chlorination, air mix, slow mix settling, carbonation, filters and storage. At a cost of $60,000. Also a 12-inch water main was added from the plant to the reservoirs.
1951 - The city underwent an extensive water main project including looping in all dead ends. Also a 2-million gallon concrete reservoir was built at the Collins Avenue site discontinuing the two reservoirs built in 1911. A booster pump station and a 500,000 gallon reservoir was built to supply the northern part of town. A 750,000 gallon pre-sedimentation basin was built at the plant site at a cost of $126,555. Designed to take care of 5 MGD demand, eliminating one stage of pumping in addition to eliminating the ponds or pre-sedimentation basins which were built in 1911.
1958 - The water plant was remodeled at a cost of $432,000. This remodeling was done without interrupting the production of the plant for a single day. The remodeled plant was increased to 6 MGD finished water. The treatment consisted of clarification, softening, stabilization, filtration, and bacteria control.
Three new rapid sand filters were added having a capacity of 4 MGD. Two accelators (or mixing chambers) were installed to a capacity of 6 MGD combined. Also built was a mechanical unloading of lime and storage facility. A new intake structure was built to house the pumps and traveling screen. This facility is designed to draw 20 MGD for the city.
Another item was switching the power from 2,200 volts to 4,360 volts. This change made it possible to receive stand-by power from the nearby oil refinery during periods of power failures, a joint venture between American oil refinery and the City of Mandan.
1972 - A booster pump station was built at the 500,000-gallon reservoir to furnish water to consumers on the north side of Interstate 94.
1975 - A 30-inch water transmission line was laid from the water treatment plant to the future 3-million gallon reservoir, located north of I-94 (Sunset Drive). A 24-inch transmission line tying in a 500,000 gallon reservoir to the 30-inch line was also laid. The total cost of the project was $1,165,000.
1977-78 - Because of the increase of oil and coal development in the area, and the expected population increase, the city had a master plan study done on the water treatment plant and distribution system.
At a cost of $650,000, work was started on the Phase I project at the water treatment plant. This included remodeling the slow sand filters installed in 1938, by installing dual media sand and anthracite coal. All the filter piping was also replaced. A main operating control panel was installed to monitor clear well levels, turbidity readings, influent and effluent flows.
Also started in 1977 was the construction of the Sunset Drive reservoir, a 3-million gallon reservoir built north of I-94 at a cost of $498,000. A booster pump station, to pressurize the system north of I-94 was built next to the reservoir at a cost of $560,000.
In 1978 at a cost of $423,768 a 20-inch transmission line was installed from the reservoirs located at Collins Avenue and Division street to Sitting Bull Bridge booster station, to supply the area south of the heart river and also to a future storage reservoir. Also an 18-inch transmission line was installed from the reservoirs located at Collins Avenue and Division Street to Old Red Trail. This replaced a portion of the 10-inch (1916) and 12-inch (1938) water transmission lines to the water treatment plant.
In 1978, construction was started on Phase II of the project at the water treatment plant. This included addition of a 350,000-gallon clear well and pump station to supply water to the sunset drive reservoir built in 1977. The project cost was $522,500.
In 1975, The Environmental Protection Agency (EPA) added restrictions on discharging to rivers and streams. The water treatment plant facility at this time discharged all its backwash water and lime sludge, including its sanitary waste to the Missouri river. This led to the city being forced into building a facility to eliminate discharge to the river.
During the planning of the lime sludge plant facility, the existing water treatment plant was at maximum capacity during heavy usage days. It was decided at this time to plan an expansion to double the plant’s capacity from 6 MGD to 12 MGD.
The water treatment plant portion was $4.3 million, funded by the city. The lime sludge removal plant was $2 million with 75 percent of the cost funded by EPA. Construction started on both projects in April 1985. Also part of this project upgraded some areas within the existing plant. Eliminating all discharge points to the river, including the sanitary waste which will be handled by using a septic tank and a mound drainage system for disposal.
Dirt from the excavation site was used to stabilize the river bank, and rip rap. The building sets on 295 piling (40-foot lengths).
Some of the items worked on were an addition to the intake structure to house a carbon feeder room for taste and odor control. A 24-inch pump header and piping for increased flows to the excising pre-sedimentation basin,(sand and silt) and a 36-inch gravity feed line from the pre-sedimentation basin to the new 12 MGD pre-treatment basin, which will also remove additional sand and silt.
Four mult-media controflow filters using anthracite coal, sand and garnet rock, capacity of 4 1/2 gallons/min/sq ft. where built. The backwash water is pumped back to the pre-sedimentation basin and the filtered water flows by gravity to our 630,000-gallon clear well and is then pumped to our city reservoirs.
New chemical feeders where also added to the excising plant. The lab was enlarged and a new operating control panel was added for improved plant operations.
The power supply was upgraded from 4,160 to 12,000 volts to the water treatment plant area. A standby 750 kva diesel generator, 600 kw, was installed to handle about a third of the plant's electrical load in the event of a power failure.
The lime sludge plant consists of two 120 gpm duplex pumps which pumps the sludge from treatment plants, to the thickener basin, from this basin two 80 gpm screw type pumps lifts the lime sludge to the 2-belt filter presses. The sludge cake is moved by a conveyor to a hopper and then hauled by truck to the city landfill.
1992 - Approval was given by the City Commission to sell water to Missouri West rural water. Water service to Missouri West customers began in October 1993.
1993 - At a cost of $982,000, construction began on a 24-inch water transmission line, replacing the remaining portion of 10-inch (1916) and 12-inch (1938) from Old Red Trail to the water treatment plant, for supplying water to the reservoirs at Collins Avenue and Division Street.
Mandan covers an area of 11.84 sq.miles and has a total of 132.33 miles of water mains. The city also has 100.9 miles of sanitary sewer mains.
1999 - Due to the rapid growth in the higher elevation in south east Mandan, the 8th Ave SE booster station was built in 1999 at a cost of $362,200.
Also in 1999, the Sharon Heights booster station was upgraded at a cost of $268,650. To meet future demands in the system, north of I-94 and to serve as a backup system in the event the Sunset Drive booster station fails. The existing structure built in 1972 was dismantled and replaced.
A panel view system was installed at the water treatment plant in 1998-99, to collect operational information from all booster stations and reservoirs in the city. A computer system to collect inputs from various plant functions and turbidity meters on all filters was installed in 2000.
2000 - The upgrading of Collins Avenue booster station began in the fall of 2000, all new pipe-motors-pumps, and electric service to the station where installed at a cost of $119,700.
The 1986 Safe Drinking Water Act (SDWA) amendments and the 1996 reauthorization of the SDWA has focused water producers on compliance with new regulations regarding various microbial and chemical contaminants, these regulations have a significant impact on the treatment of surface waters.
To address the impacts of current pending and future water quality regulations on individual processes and related deficiencies identified within the Mandan water treatment plant resulting from water quality monitoring requirements, the City of Mandan authorized a consultant engineering firm to complete a preliminary engineering report. The purpose of this report was to develop corrective improvement alternatives for excising deficiencies (with respect to water quality regulations) and to provide special consideration of the potential result to update the facility plan which was completed in 1978.