Pipe Collapse in an Amusement Park—Now What Do You Do?

Condition assessments of aging infrastructure are important to identify the remaining useful life of a utility's assets and to develop a plan to rehabilitate and/or replace the infrastructure. Jacobs Engineering Group Inc. (Jacobs) assessed and prioritized recommended improvements for 33,000 feet of pipe in the Elm Fork North Interceptor System located in northern Dallas County. A 1,200-foot pipe section through Sandy Lake Amusement Park was given a high priority ranking due to a deteriorated condition. In September 2010, before a design contract for improvements was scheduled to begin, a 40 foot section of the existing 48-inch RCP sewer main collapsed in Sandy Lake Amusement Park, causing a sink-hole which compromised a rail line for the park train ride. The pipe owner Trinity River Authority of Texas completed an emergency repair, and approved a final design contract to move forward with the planned improvements. The park's seasonal schedule and surface features made design and construction scheduling a challenge. This paper provides a summary of the project history which included a rehabilitation study, alignment study and environmental assessment, and final design. The final design presented several challenges and this paper discusses some of the challenges including scheduling, bypass pumping requirements, stakeholder coordination, easement negotiation and acquisition, and design considerations proposed for the project. This paper will also discuss the sensitive nature of the park operation combined with the tight corridor which led to the need to closely consider every detail of the excavation and bypass pumping operation during design.