No Matter What You Call It, Planning sets the Foundation for Success

Before any water utility starts working on detailed plans and specifications―which I’ll refer to as “Design” in this blog―for water distribution and wastewater collection system projects, there is a phase that typically involves the word “Planning.” The one consistent aspect of planning is that different utilities use various terms for it, such as capital planning, master planning, preliminary design, comprehensive planning study, basis of design report, or project prioritization, to name a few. In this blog I will try to identify what I think is the best terminology.

I generally based my terms on the planning horizon:

• Master Planning involves using long term population and flow forecasts to lay out major facilities over a fairly long-time horizon.
• Capital Planning looks at projects needed in the next few years. It includes developing pipe sizing, pump station locations and sizing, tank locations and sizing for the design phase, and cost estimates to evaluate project funding.

Master Planning: The Big Picture

Master planning (also referred to as comprehensive planning studies) uses 20- to 50-year forecasts to lay out major transmission or interceptor piping, locate pump stations and tanks, and determine implementations timelines. While the pipe and other facility sizing should be reasonable, they don’t need to be optimal because all population forecasts have some degree of inaccuracy. (If you can forecast the future perfectly, you should be in the stock market.) Hydraulic analysis of key facilities, supported by modeling, ensures the system will actually work. Details can be worked out later. Plans should be flexible enough to accommodate a wide range of future scenarios.

One of the most critical, and relatively irreversible, decisions in master planning is establishing pressure zone boundaries and corresponding tank overflow elevations. While paralleling a pipe or upsizing is relatively straightforward, altering tank overflow elevations or pressure zones is significantly more challenging once they are set. The first few years of the master plan feed into capital planning.

Capital Planning: From Plan to Reality

Capital planning (also called preliminary design, basis of design report, or project prioritization) is usually guided by the latest master plan. However, decisions made at this stage are going into the ground, so they need to be right. Hydraulic analysis is critical to test design decisions and ensure their functionality under various conditions―average demand days, low-demand periods, peak demand, over the whole planning horizon. They need to provide needed fires flow requirements at key locations, and how the system will respond when there are power outage, and pipe breaks. Bentely’s scenario management tools fit this workflow very well. This phase is also where pipe replacement and rehabilitation projects need to be prioritized.

There is usually not enough money available in the capital budget to fund all of the proposed projects across the utility as distribution/collection projects must compete with capital projects in treatment, metering, laboratory and other areas based on costs/benefits and type of funding. Projects funded by State Revolving Fund loan and grant programs (in the U.S.) typically are looked on favorably. Projects designed to meet legal requirements, such as consent orders and other regulatory compliance issues tend to go to the top of the priority list. Ultimately, capital planning determines the scope and cost of projects. Poorly justified projects often fail to secure funding. The need to defer/downsize projects compared with the pain of rate increases is often the topic of discussion.

Modeling the Plan

Throughout all planning stages, the hydraulic model is a key input to support the need for and the scope of projects.

The above insights are based on my experience and may not cover all possible planning approaches. I’d love to hear from readers about their planning processes, terminology, and how they use hydraulic modeling along the way. Feel free to email me at tom.walski@bentley.com. If there is sufficient feedback, I’ll share comments in a future blog post.