Bismarck East Zone 3 Modeling
City of Bismarck, ND
Proposed East Zone 3, a newpressure zone located in the NE corner of the City of Bismarck, has experienced relatively rapid domestic growth during the past few years. The rapid growth in this area resulted in unacceptably low water pressure and subsequent complaints from the local residents, as well as low fire flow capabilities and inadequate storage. This problem was pronounced to the extent that two privately owned booster stations were constructed in an effort to sustain adequate pressure. As such, it was possible that further development and expansion would be precluded without infrastructure improvements to address the water pressure, fire flow, and storage issues. The situation prompted the City to respond by accelerating the design and construction of a booster station, and potentially, a 1-million gallon elevated storage tank. These improvements were recommended for implementation sometime in 2007 - 2015 (in a 2001 Master Plan Update completed by another consultant).
Distribution system design has traditionally been conservative to the point of creating long residence times in both storage and piping that promotes chlorine residual decay, taste and odor problems, and disinfectant by-product formation, among others. Similarly, from an operations perspective, storage facilities are often kept full in anticipation of emergency situations, potentially resulting in further water quality degradation. Although the proposed project could have been considered acceptable for resolving some of the existing problems related to flow, pressure, and storage, AE2S identified a number of issues concerning water quality, the project’s short and long-term integration and interaction with the existing system, critical operational aspects, and the public investment potentially expended now and in the future. To address these issues, AE2S developed three alternatives to the proposed project that better balanced the multiple objectives.
As a result of detailed modeling and assessment of the proposed project, the alternatives, and certain other infrastructure development concepts, the best solution was identified and recommended. The preferred solution enabled the City to design the improvements themselves, and ultimately construct the project that provided the greatest short and long-term value. Value was achieved by recognizing and appropriately balancing pressure, flow, and fire protection with capital, O&M, operational, and regulatory issues, such that improvement elements for East Zone 3 and other zones with which it interacts, were consistent.