The City of Milton has operated a Wastewater Treatment Facility since the mid 1900’s. In 1984 the current oxidation ditch facility was constructed and has allowed the City to grow into the 21st century. In 2006, this plant underwent a major upgrade to modernize and enhance the treatment process. Since the effluent is a surface water discharge into the Blackwater River, the City has taken steps to ensure that this “Outstanding Florida Water Body” is protected by performing a Water Quality Based Effluent Limitation (WQBEL) study.
While being centrally located in one of Florida’s fastest growing counties, Milton strives to be a leader in protecting its natural resources.
The City’s wastewater treatment plant operations perform their duties in a responsible and professional manner, while meeting or exceeding State of Florida standards and rules, in addition to the public’s health, safety, and welfare. Operations at this facility have three (3) primary goals:
- Produce the very best effluent quality possible
- Help ensure the water quality of the Blackwater River
- Provide this quality and protection at the lowest possible cost to the citizens of Milton and its customers
Structures and Equipment
The current facility is permitted at a flow rate of 2.5 mgd and has the following treatment unit processes:
- Master pump station consisting of four (4) 2000 gpm submersible solids handling pumps. Prior to receiving the influent, all flow travels through open channel comminutor in order to reduce solids sizing.
- Rotating fine screen to remove materials greater than 0.060 inches or 1/16 inch.
- Aerated grit chamber to remove settable grit, along with grit pumps and a grit screw conveyor. All grit and solids are collected and disposed into the local landfill.
- Flow equalization basin to smooth out variations flow throughout the facility. Flows are then pumped to the next structure using three (3) variable speed, vertical turbine solids handling pumping units.
- Anoxic reactor basin where both pretreatment effluent and internal recycled flows are combined, mixed and then returned to the aeration basin for further processing. This basin is equipped with two (2) slow speed mixers.
- Flow then travels by gravity to the aeration basin which is based on the “oxidation ditch” design using the horseshoe configuration. Aeration is achieved using two (2) 100 Hp variable speed slow speed surface aerators.
- Clarification is provided using three (3) circular secondary clarifiers. This design includes a center feed with a perimeter effluent trough. At this point the solids are settled and the clarified effluent flows to the filtration system. Solids are collected and removed using a Return Activated Sludge/Waste Activated Sludge (RAS/WAS) pumping station.
- The filter feed pump station is equipped with three (3) solids handling submersible pumps and feed the clarified effluent to the filters.
- Filtration is provided using two (2) cloth media discs filters rated at 2.5 mgd average daily flow (each).
- Chlorination /disinfection is accomplished using four (4) channelized chlorine contact chambers.
- Flow is then directed into an effluent pump station structure prior to discharge. This structure provides multiple functions and is equipped with:
- An on-site reuse/process pump that provides flow for wash down and other process requirements. A hydro pneumatic pressure tank provides for automatic system operation.
- Two (2) reject pumps for pumping sub-standard quality effluent to a 3.0mg ground storage “reject” tank.
- Further space is provided for future off-site reuse pumps.
- Post aeration and de-chlorination are provided by a “stair step” style cascade structure and the final effluent flows by gravity into the Blackwater River.
- After the flow process is split at the clarifier, settled solids or “sludge” is either returned for further mixing with raw sewage or wasted into digesters for further processing.
- Solids diverted to the aerobic digesters are aerated using floating, surface type, aerators. Biosolids are processed in order to meet the requirements of a “Class B” biosolids that are suitable for land application.
- Since the majority of the weight of sludge is water, a dewatering facility has been constructed where the sludge is dewatered using a “centrifuge” style system. The dewatered solids are then disposed of using contracted land application. As an alternate source, the City could dispose of the biosolids at the local landfill.
- In addition to the major structures and equipment outlined, the plant is equipped with offices, laboratory, electrical rooms, emergency standby power and other related support facilities.
- The treatment facilities are operated, controlled, and monitored using a Supervisory Control And Data Acquisition (SCADA) system. This system allows for more efficient operation of the equipment while maintaining the highest reliability possible.
Compliance with Standards
The City of Milton’s wastewater treatment facility is permitted under F.A.C. Chapter 62-620 as a 2.5mgd (three month average daily flow) activated sludge treatment facility.
The current permit is due for renewal March 7, 2008. As a requirement of the present permit, a WQBEL was completed on the receiving waters of the Blackwater River. Those findings and recommendations will be included as part of the permit renewal. In general, the study found that this facility had no adverse impact on the Blackwater River and its environment.
Even though this facility is not required by the FDEP to meet Advanced Waste Treatment (AWT) limits, the effluent produced consistently meets AWT standards. Under a pretreatment ordinance the City strives to reduce contaminants from entering into the wastewater collection system which would interfere with the operation of the system or prevent the treatment facility from meeting its permitted limits.
I & I Control / Future Growth / Service to the Community
In recent years the City has undertaken major sewer system rehabilitation by performing a system wide Inflow and Infiltration (I/I) Study which identified over 30,000 feet of sewer and related man-holes that were rehabilitated in an effort to reduce inflows by more than 250,000 gpd.
The City is looking to future growth by performing utility studies along the major growth corridors to the West, North and East of Milton. In conjunction with these studies, the City has acquired property in the Santa Rosa County Industrial Park in East Milton for a future wastewater treatment plant site. Planning for this site is underway. In addition to the studies, the City is reviewing its effluent disposal options including public access reuse, spray irrigation and other land application methods.
In the late 1990’s, the City formed a “Long Range Wastewater Planning Committee” to set goals for providing wastewater collection and treatment in the central Santa Rosa County area. A cross section of business, professional, military, local government and private sectors were represented. A general outline look at establishing a reasonable service area; future sites for wastewater treatment facilities; working together to obtain/maintain the highest water quality in the Blackwater River Basin; explore funding services for central sewers; expansion of the existing wastewater treatment facility; review current classifications of the Blackwater River and inflow and infiltration reduction.
Working with the State of Florida and Santa Rosa County many of these goals have been completed. But with the completion of these goals comes new ones. The City of Milton will continue to provide the best possible service to its citizens and the community.
Awards / Recognitions / Hurricanes
- The City of Milton wastewater treatment facility has received an “EPA Operation and Excellence Award” for small secondary plant category.
- The facility consistently receives satisfactory inspection reports from the Florida Department of Environmental Protections (FDEP). One report read “An extensive amount of operational control data is collected and utilized to provide the opportunity to make informed decisions”. This leads back to the first goal of the Mission Statement, “produce the very best effluent possible”.
- In 2004, Hurricane Ivan created a 16 foot tidal surge and flooding at this site. Within 36 hours, the facility was back operating at or near normal conditions. All major equipment was able to operate uninterrupted on standby power until electrical service was restored. Wastewater Superintendent, Ricky Hinote said “After the Hurricane, all we had to do was remove the debris from the clarifier and we were ready to go”.