Developing a Project Technical Criteria Document - Design-Build for Water and Wastewater Projects - page 168

I&C with other networks or remote sites needs to be addressed. The programming
requirements should be listed as well.
Miscellaneous system criteria. Other systems, such as those for security or
communications, can be included in this section.
Performance Requirements
The performance requirements for a technical criteria document are considered one of
the most difficult sections to develop and negotiate. Putting owner expectations into
clear, concise language and making sure that it is consistent with the other design criteria
that have been established are not simple tasks.
The type and number of performance requirements or guarantees differ for each proj-
ect. The possible scenarios for testing a new facility are countless: determining what tests
provide data that are the most relevant and realistic for a new facility requires a thorough
understanding of the owner's expectations, the plant's ability to meet the stated require-
ments, and the risk that the design-builder deems to exist for each guarantee or requirement.
The following discussion highlights some of the key recommendations for devel-
oping performance guarantees. Canney (2006) also describes considerations for perfor-
mance guarantees.
Water quality envelope. All of the guarantees should be met when the influent water
quality, for either a WTP or WWTP, are within the design water quality envelope. If the
water quality during performance testing is outside of the design water quality envelope,
the plant should not be expected to perform optimally. An example would be a raw water
turbidity or solids loading that is higher than the maximum design value; the water plant
may or may not be able to withstand that higher load for the testing duration.
Care should be taken in how the data is presented in the water quality envelope. A
table showing only average values would be difficult to evaluate through performance
testing because it is unlikely that all the water quality constituents will be at the average
value on the day of testing. A range of water quality is typically provided, with minimum
and maximum values. Average values can still be provided, as they are used in the evalua-
tion of some design parameters. Owners should review carefully the minimum and maxi-
mum values included in the water quality envelope because they could drive the design to
an extreme condition (e.g., requiring a larger basin or more membrane area), and if that
minimum or maximum only occurs rarely or happens to be an outlier, then a more appro-
priate minimum or maximum value for the envelope should be determined.
If a large amount of water quality data is available, proposers like to review it. The
data can be statistically manipulated to show the probability of certain maximum or mini-
mum values (e.g., the 95th percentile analysis), and this helps fine-tune the design.
If very little data are available, the owner should disclose that information to the
proposers and implement a sampling plan prior to design, if possible. Having some data
is better than no data.
Requirements and guarantees. When establishing the requirements and guarantees,
the possible primary and secondary process performance guarantees should be evaluated.
This includes the water quality requirements from the governing regulatory body, as well
as any guarantee values deemed appropriate by the owner for performance with regard to,
for example, consumption of power or chemicals, noise, or odor.