Every capital project requires a host of decisions ranging from process design to equipment selection to the execution method. Although it's certainly possible to execute a project solely with in-house resources, many large plant improvements and expansions have constraints that preclude this path. These may include schedule, special technical competencies and company policies.
The City of Rock Hill owns and operates municipal utility plants and distribution systems that provide 70,000 customers with power, drinking water and wastewater treatment (see Figure 1). Rock Hill is located in one of the fastest growing and economically diverse areas of the southeastern U.S.
When Rock Hill decided to upgrade the control systems at its drinking water and wastewater plants, a fast-track schedule forced the city to consider outsourcing part of the project work. It simply couldn't afford excessive downtime, and wanted to replace some older control system components quickly before they failed.
Out with the old
Figure 1: Widely dispersed processes and equipment made distributed control a must for this City of Rock Hill, S.C., treatment plant.
Historically, the city has preferred to use in-house resources for as much capital work as possible.
Despite the city's preferences, schedule constraints forced it to consider outsourcing part of the work for each project. The first project it was a control system upgrade for its drinking water plant.
Even though the city had expanded and upgraded the plant capacity, the facility's basic control system had remained largely unchanged. Operators still used chart recorders, digital meters and various measurement instruments to monitor and control the process. Control and record-keeping was mainly manual and mechanical.
During the late 1990s, enactment of the Interim Enhanced Water Treatment Rule established more stringent requirements for periodic sampling of water quality perimeters. The monitoring frequency for turbidity increased and retention requirements also increased.
Some of these data were available electronically and were saved for record retention via chart recorders. However, the recorders didn't provide a means for analyzing data or setting alarms for out-of-spec process conditions. Concurrent with the changing regulations, the engineering and maintenance staff recognized that the manual electromechanical control systems used at each filter console were inadequate and obsolete and needed to be replaced.
In-house versus outsource
The first task in the control system upgrade project was to develop a high-level conceptual design, a rough schedule and task list. These front-end activities revealed that this was going to be a substantial project, with roughly 1,050 digital inputs, 500 digital outputs and 350 analog inputs and outputs.
Although the city wanted to replace and upgrade the control system in-house, after reviewing schedule requirements, it became clear that this wouldn't be feasible. The next step was to decide which project activities and tasks should be outsourced. The city concluded that only design and installation could be done in-house. Control panel assembly and software development would have to be outsourced.
The next step was preparing a bid package. Drawings included a detailed layout of the plant showing equipment layout and proposed locations for the new control panels. Also included were function drawings, among them a view of the plant piping and a process flow outline.
Because this was to be a fixed-price contract, the project manager wanted to gauge the market prices before putting the project out to bid. A close friend and former boss who now works for a drive systems integration firm coached him in the art of system pricing based on I/O points, hardware usage and programming time. Costs for software development and panel assembly were estimated and found to be within the city's budget, and the work was put out to bid.
Although a cost-plus contract could have been used, the city felt that a fixed-price contract would give it more control over the final project cost. Fixed-price contacts require much more preparation and up-front work, but the extra effort is more than justified.
The city solicited bids from five control systems integrators, but received only one bid. The aggressive schedule apparently deterred the other four. The sole bidder was Instrumentation Services (ISI) of Charlotte, N.C., which had performed control system and instrumentation maintenance work at the city's water plant for 15 years, so they had detailed knowledge of the plant's operations.
ISI's lead engineer for the project, John Tillman, praised the project team's preparation, showing how important front-end work is to focus goals and maximize flexibility.
Water in, water out
In concert with the control system upgrade at the drinking water plant, the city also decided to upgrade control systems at its wastewater treatment plant. This plant is considerably larger than the drinking water plant.
The wastewater treatment facility covers about 40 acres, so connection from building to building required miles of fiber optic network cabling. Front-end design estimates called for 1,600 digital inputs, 500 digital outputs and 300 analog inputs and outputs.
The control systems upgrade for this plant followed a path similar to that for the drinking water plant, except that the city could keep panel assembly in-house and only outsource software design.
Ultimately, Rock Hill chose Interworx.net of Cumming, Ga. During the conceptual design phase, the project team decided to use Indusoft HMI software and hardware with Think & Do programming software from AutomationDirect, a program that the contractor was familiar with.
Although the project team considered awarding both contracts to one firm, it decided that, given the project size and the limited timeframe, it would be better to divide the work. ISI was selected to upgrade the drinking water control system because they best knew the plant. Interworx.net was chosen to upgrade the wastewater control system because they were most familiar with the control system hardware and software.
The city's up-front engineering was put to the test during the project execution, but both contractors performed well. There were also some fringe benefits from the project, including implementing a CE-based PDA handheld computer that allows city engineers to monitor and troubleshoot the control systems via a wireless phone modem.
There were few surprises with the projects. However, given the potential drawbacks (see Table), the city still prefers to outsource only when needed.
Costs for both were comparable. The chief benefits of in-house execution are the degree of familiarity that the staff gains with the new system and equipment, and the feeling of ownership engendered through hands-on design, installation and start-up. Nevertheless, Rock Hill plans to continue to outsource when needed.
These contracts were large investments and the work had to be done right the first time. Any required rework would have overrun the budget and extended its completion schedule.
Remember, contractor selection isn't just about the price agreed upon in the original contact. It's also about the final total cost, schedule and the quality of work.
Jon White, maintenance superintendent, City of Rock Hill Water Treatment Plant, Rock Hill, S.C., may be reached at [email protected].