WHAT DO YOU DO WHEN YOUR COLLECTION SYSTEM MODEL RETIRES?

The Las Vegas Valley has been one of the fastest growing communities in the United States for the past 15 years with an annual average growth rate of over 5 percent during that period. In fact, over the past 4 years, Las Vegas' population has nearly doubled to over 1 million residents. With the flood of new residents comes a tremendous need for infrastructure to meet the water and wastewater demands of this growing community. In addition to the local residents, Las Vegas has an enormous transient population (tourists), which during certain events can attract more than 500,000 visitors over a single weekend. A recent unique phenomenon to the Las Vegas Valley (LVV) is the wide spread growth of vertical construction (high-rise residential dwellings), especially along the Las Vegas “Strip.” A majority of the new high-rise development is occurring within the Clark County Water Reclamation District's (District) service area. The design of the existing infrastructure did not anticipate this higher density and the associated higher flows.In over 50 years of service to the community, the District has never used a software model to help monitor or analyze their collection system. Instead of using a software model, the District's senior collection system manager was responsible for the following: 1) developing and maintaining the District's collection system information database which consists of operations and maintenance data for over 1,700 miles of sewer pipe and 21 lift stations, 2) recommending capital improvement projects, and 3) approving developer plans to connect to the collection system.Without the use of powerful software and computer solutions which can efficiently analyze a collection system, District staff found it difficult to determine where and when future capital projects should be implemented and if system deficiencies could exist from new development. In addition, as mentioned above, growth in the District's service area continues to outpace projections and indications are that flows will exceed current projections within the present planning horizon. With the impending retirement of the District's senior collection system manager, the District embarked upon the development of an Integrated Facility Master Plan (IFMP). The goal of the IFMP is to update the flow projections to identify conveyance capacity within the existing sewers, assess whether flows in excess of the current planning value could be conveyed to their treatment facility, when and where those flows might occur, and the additional infrastructure needed to convey and process those flows.As part of the IFMP, the District developed a dynamic hydraulic model and master plan for their collection system. Ultimately, the collection system model will be a skeletonized version of the District's senior collection system manager's knowledge and understanding. The IFMP will allow the District to implement required capital improvement projects when they are needed. The hydraulic model and master plan will provide District staff with a thorough and comprehensive understanding of their collection system.This paper develops several techniques for determining wastewater flow within a service area using population projections, water demand, and land use; includes details of the collection system analysis; and the benefits realized by the District in developing a hydraulic model. The purpose of this paper is to summarize the approach taken in developing a dynamic hydraulic modeling tool and to illustrate the benefits that this new tool provides the District in master planning efforts now, and through buildout.