Town of Prosper

CHALLENGE

During the past decade, many towns and cities in Texas have experienced unprecedented growth. In 2015, the Cities of Georgetown and New Braunfels were the fastest growing cities in the United States at growth rates of 7.8% and 6.6%, respectively. Last year, the Town of Prosper’s growth rate was over 11%!

A new 1500–acre mixed-use golf course community is being master planned by LandPlan Development in the southeastern most quadrant of Prosper. This new development, known as Brookhollow, may add over 11,000 new residents to Proper’s current population of 17,800! Therefore, strategic water and wastewater infrastructure planning and implementation is crucial for Prosper to thrive.

SOLUTION

Walker Partners was chosen to conduct a wastewater feasibility study to meld the Town of Prosper’s Capital Improvement Program and the City of McKinney’s Wastewater Master Plan to LandPlan’s Master Development Plan. As a part of this study, peak wet weather wastewater flows generated from the “ultimate” build-out from the new Brookhollow development were combined with the “ultimate” build-out flows of the Town as calculated in Prosper’s Master Plan. Next, four alternative pipeline routes were analyzed in order to determine the most economically feasible option which would expand Prosper’s existing service area and would complement the design and layout of the Brookhollow development. These four alternative alignments and accompanying benefit-cost analyses were compiled in our “Preliminary Engineering Report” (PER) and summarized with our clearly identified recommended solution.

Both the Town of Prosper and LandPlan Development concurred with our recommendation, and subsequently authorized Walker Partners to proceed into the preliminary and final design phases for the identified Project. Five clear, distinct challenges were identified in the PER and had to be acted on swiftly in order to meet the development schedule of LandPlan:

- The new interceptor would connect into the North Texas Water Municipal District’s (NTWMD) regional sewerage system and therefore a permit had to be obtained to tie onto their system.

- The new interceptor would have to cross the City of Irving’s 66–inch Raw Water Transmission Main and consequently, written approval had to be obtained from Irving.

- Approximately 600 feet of the proposed interceptor would have a bury depth in excess of 40 feet, half of which would be parallel and adjacent to Custer Road and the remaining half beneath an existing cemetery (Walnut Grove Cemetery).

- The new interceptor would have to cross Wilson Creek – an environmentally sensitive creek characterized by steep side slopes, a limestone rock bottom, and crystal-clear, year-round flows. One of the primary conditions of the easement granted by a private landowner to cross Wilson Creek was that no trenching (open excavation) could occur within the creek banks.

- Wilson Creek is very deep and wide and it conveys very high stormwater flowrates during and following rainfall events; consequently, an aerial crossing would have to be designed to not only span the width of the creek, but to withstand the forces generated by the high flow velocities of the runoff conveyed by the Creek.

VALUE

Perhaps Walker Partners’ greatest value to our Clients for this Project was to bring swift consensus, concurrence, and approval from all parties in an open and friendly manner. Our positive professionalism steadied the negotiations with the Cemetery in order to cross the Cemetery with a 24–inch diameter sanitary sewer. Likewise, our steadfast commitment to our Clients guided us to secure approvals from the City of Irving and NTWMD within 60 days!

Walker Partners’ passion for excellence and unsurpassed expertise with large diameter pipeline construction was our foundation for our innovative, yet cost effective, design of the Wilson Creek aerial crossing. Our attention to detail, coupled with our strategic methodology to bid the “deep” cuts by either open excavation or by way of bore and encasement, allowed the contractors great flexibility in their bidding. At the end of the day, it was the Town of Prosper and LandPlan who reaped the benefits of Walker Partner’s dedication, commitment, and depth of experience when the Project was completed for $3,243,745, or 12% below the Owners’ budgets, without a single change order! 
Walker Partners is working with the City of Gatesville to obtain State Revolving Funds (SRF) from the Texas Water Development Board (TWDB) for the plant expansion. We are coordinating and submitting the major amendment to the WWTP’s TPDES Permit to TCEQ.

The WWTP is an extended aeration facility currently rated for 2.2 MGD. Walker Partners completed a process evaluation and capacity rerate that supports an expansion without causing more restrictive permit limits and higher construction costs. This defers approximately $2 - $3 million dollars in expenditures for the City. 

completion date: 2008

location: prosper, Tx