Understanding water system plans for utilities

First step in understanding water system planning for utilities: review the reasons for creating a plan.

Use identified end goals as a basis for moving through the plan development process.

By creating a water system plan, utilities can predict infrastructure changes required at future planning horizons in an orderly and systematic manner in keeping with budgetary constraints.

Factors to Justify Developing a Water Plan:

Growth:

Might need to plan for future growth to serve parts of existing service area not yet developed, or to accommodate service area expansion.

Periodic updates may be driven by local Authorities Having Jurisdiction.

Regulatory requirements/changes:

May require plan updates that consider water quality, chlorine residual and residual pressure improvements in distribution system.

Example: EPA mandating reductions in lead and copper at points of consumption, and reductions in PFOS compounds in finished water.

Maintaining proper chlorine residual levels in remote parts of distribution system may require installation of localized chlorine injector facilities.

Booster pump stations may be required to maintain adequate pressure in areas of higher elevation.

Reliability:

Need to consider reliability of existing infrastructure.

Much of current infrastructure may require upgrade or replacement.

System efficiency:

Need to consider new technology and optimization for future system improvements.

• Supervisory control and data acquisition (SCADA) system implementation or improvements
• Variable frequency drive (VFD) pump controls
• Diversion of water to other parts of the distribution system via valve closure

Steps to Create a Water System Plan:

Each step is an essential part of overall plan.

Planning and Design Criteria:

Identify:

• Minimum pressure
• Minimum and maximum pipeline velocity criteria
• End criteria for future customers
• Minimum storage requirements
• Fire flow criteria

Model creation:

Identify what is needed and desired.

Determine if full model rebuild is necessary, or whether existing model can be updated—for example, how up-to-date is the water system GIS?

Water demand projections:

Examine meter billing and consumption records for at least recent 12 months, including maximum-day and peak-hourly demand conditions.

Examine population projection data from local Planning Agencies to estimate demands for future planning horizons.

Model calibration:

Confirm that model is reasonably calibrated according to published literature.

Water supply evaluation:

Determine current and future water supply needs.

Distribution system analysis:

Evaluate whether system can adequately meet existing and projected demands, including satisfying fire flow requirements.

Determine what improvements are necessary to satisfy design criteria for both current and future customers.

Capital Improvement Plan:

Based on previous steps, develop Capital Improvement Plan for each planning horizon, so utility owners can justify budgetary requirements and the scheduling of improvements.