The purpose of the design phase is to transform the requirements into complete and detailed system design specifications. In the design phase, you start to ask the “how” questions. During the design phase, you should begin to look at the many potential solutions and narrow down choices to determine the most effective and efficient way to construct the solution. The design phase answers the questions about “how” you will build the best solution. At the end of the design phase, you will have a logical solution defined.
The design phase will impact all other phases of the asset’s life cycle and can impact costs in all phases. Any mistakes or problems that were not considered during the design phase will carry throughout the asset’s life. Therefore, it is important to involve many different types of people, including operations and maintenance staff, during the design phase. It is also important to consider other utilities and departments within the organization that might have assets or projects within the proposed construction zone. These assets will likely be impacted during construction, and it is necessary to consider the costs associated with these impacts. In some cases, it might be better to choose a different location altogether. When these impacts add costs to the project, it is important to consider them.
Other considerations during the design are the Level of Service the asset is required to provide and whether that level will be met following completion of the project. While it is important to think through the potential problems that might be encountered during design, it is likely that this phase will not be perfect. Changes might be necessary, and funding should be available for the potential changes. It is still cheaper to make the changes in this phase than in construction or operation.
The City of Portland utilizes a Green Street Field Inventory Form to track construction impacts in the city. Portland provides the form to utilities and systems that might have infrastructure in the proposed construction area. The outside systems can use the form to notify the Green Streets Program of any infrastructure or items of concern in the area. The form collects relevant information with questions about when and who completed the inventory form; stormwater infrastructure; street infrastructure; water service; private utilities such as energy, communication, and gas; existing vegetation; facility design; supplemental system benefits; a sketch of the site; facility performance; design feasibility; cost; and notes.
Design and Operation: Two sides of the same coin
Design and operation are two sides to the same coin. The best design will fail to achieve its desired objectives if it is not operated and maintained properly. Likewise, the best operation and maintenance will not fix a bad design. The best projects incorporate both.
If the scope of the project is large enough, the design might be completed outside of the system. In the case that an outside entity, such as an engineering firm, is needed to design the project, the system will likely need to develop a Request for Proposals (RFPs). The Resources section has some tools to use in developing an RPFRequest for Proposals.
The successes and failures of the design phase will be carried throughout the project’s life. If a design does not accurately reflect elevations for water to flow by gravity, the project can be a failure from the start. This type of mistake can be avoided with careful plan review and feedback from a variety of people within the system. Sometimes situations arise that cannot be known during design. When construction of buried assets starts, it is possible the contractor will encounter rock. The design will have to be modified or the rock will have to be removed. Either way, change order work is necessary. Therefore, project construction costs should include contingency funds.