Distribution & Collection

Mission Statement


Our mission as the City of Lake City Utilities, Water Distribution and Wastewater Collection is to meet and exceed our customers expressed, and unexpressed, expectations for water and sanitary sewer services, in a productive and efficient manner.

 

Our goal is to train and develop our personnel to meet future growth. The Utility Department is to have a continued process of improvement through public trust, flexibility, innovation, competitiveness, responsibility, and accountability, through employee excellence and satisfaction. We will support all other City Departments.

 

Goals and Objectives 

  • Complete all projects assigned by Utility Manager and Utility Board satisfactorily and under budget for the fiscal year.
  • To establish values, work ethics, and working relations between employees and staff.
  • Develop quality performance measures.
  • Prioritize objectives.
  • Train and cross train employees.
  • Provide a safe and secure distribution system.

 

Frequently Asked Questions

 

 

 

The function of the Water Distribution Department is to safely transport potable drinking water throughout the network of system pipes from the source to the point of use including raw water mains from the lake source. The operating personnel are engaged in maintaining the system piping and appurtenances in a responsible, approved manner while meeting State, Federal and local rules and regulations with cost efficiency and productivity in mind.

 

 

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The principal efforts are directed towards prompt, effective service to the public and overall service excellence as the key response effects. The department is responsible for maintaining storage facilities, fire hydrants, meters, valves, pressure regulators, air valves, and other components while providing assistance and support to other departments.

 

 



The primary function of water distribution systems are to:

  • Meet the water demands of users while maintaining acceptable pressures in the system.
  • Supply water for fire protection at specific locations within the system, while maintaining acceptable pressures for normal service.
  • Provide sufficient level of redundancy to support minimum level of service during emergency conditions (i.e. power loss or water main failure.)

 



Components


The components of a water distribution system include:

  • Pipelines - carry water from the treatment facility to the users.
  • Transmission mains - the largest pipes which carry flow from the water treatment facility to the network. These pipes are often greater than (D > 600 mm).
  • Feeder mains - (pipelines which feed flow from the transmission main to the individual pipe networks of every service area (D _ 400 - 500 mm)
  • Distribution mains - the grid of pipelines which provides service to all users (D _ 150 - 300 mm)
  • Service lines - pipelines which go from the distribution mains to the individual house/facility. The individual lines are sized as per momentum equation (Darcy-Weisbach) and energy equation (head loss equation.)
  • Pumps - maintain required pipeline service pressure. Because of variable demand requirements multiple pumps or pumps with variable motors are often required.
  • Booster pumps - maintain required service pressure along long pipelines
  • Fire-service pumps - provide additional capacity for emergency situations Pumps operate at the intersection of pump performance and network system curves and must adjust to highly variable demand. As such, multiple pumps may be required for steady, cyclical, and emergency demands
  • Storage facilities - accommodates demand fluctuation by storing excess water until it’s necessary
  • Ground storage - ground level storage which discharge water to the system with a pump elevated storage - storage tank at the elevation required to deliver water at required pressure (or head).
  • Valves - required for removing components and rerouting flows
  • Meters - required for monitoring flows



Operating Pressure of System


The required system pressure demands on several considerations listed below:

  • excellent flow to a 3 story building requires 290 kPa
  • adequate flow for residential areas requires 240 kPa
  • adequate flow to a 20 story building requires 830 kPa (Please note this isn’t desirable because of waste and leak, instead most tall buildings have their own on site pumps. Generally, pressures of greater than 650 kPa should be avoided)
  • adequate flow to most systems recommends 410-520 kPa ordinary consumption for 10 story buildings
  • adequate service for sprinklers in buildings of 4-5 stories
  • adequate fire hydrant service
  • adequate margin for fluctuations due to clogging and other losses

Water Demand


Demands of the entire population must be considered before designing a water distribution system. Possible demand sources include:

  • residential
  • commercial
  • industrial
  • public

The average city requires 660 liters/day/person. Typical distribution of water use for an average city is as follows:

Category Average use Percent of total (liters/day)/person:

  • Residential - 260
  • Commercial - 90
  • Industrial - 190
  • Public - 70
  • Loss - 50
  • Total - 660

Water Demand Projections


When planning for a water supply system, the water demand at the end of the network design life is generally used as the basis for the project design. Because the demand of the system 20 years in the future is not known, it is necessary to make some kind of prediction or forecasting about the municipality growth. A variety of Forecasting models exist, including:

  • Aggregate models - treat the population as a whole
  • Disaggregate models - break up the population into groups and predict the growths of each group. An example of this is cohort analysis which segregates age and gender. These models require large quantities of data.
  • Empirical models - are based solely on data. Please note that after 10 years, empirical models are as reliable as disaggregate models.
  • Population growth is not generally steady and tends to grow at varying rates.
  • Geometric growth phase - occurs when there are wide open spaces and is modeled with:
  • Arithmetic growth phase - occurs after the initial growth has leveled off and is modeled with
  • Declining growth phase - occurs when growth becomes limited by available resources. Each of the above phases is generally limited to 10 years in duration. For situations when a longer projection is required a long term projection can be approximated with an S-curve (most common used is a logistic curve)

Please note, that for projections of less than 10 years a 10% error can be expected, but for projections greater than 20 years a 50% error can be expected.

 

Demand Variations


The demand in a water distribution system varies, daily, weekly, seasonally, and in the case of emergencies such as fires. The range of demand conditions are specified with peaking or demand factors.

In emergency situations as a result of fires the demand may increase significantly. The most common method for estimating peak demands due to fires is a method proposed by the Insurance Services Office (ISO).

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