Northwest Lubbock Drainage Improvements Phase 2 is an extension of the Northwest Lubbock Drainage Improvements Phase 1/1a project. This phase focused on relieving intermittent yet long-term flooding at Maxey Park. A hospital at that location experienced significant loss of accessibility during flood events. Large numbers of residences were also built below the playa overflow elevation and had suffered with long-duration flooding. Reducing flooding benefitted local residents, hospital district employees and visitors, and the traveling public.

PSC designed Phase 2 of the Northwest Lubbock Drainage Improvements and served as Engineer of Record. This project, 10,700 LF of storm drain at depths up to 47 feet, had four tunnels with a total length of 3000 LF. The contract documents were written to allow the contractor a great deal of flexibility in choosing the best materials and installation methods, which provided the best value for the community.

The project design allowed the contractor to choose fiberglass reinforced pipe or concrete box or pipe. Fiberglass pipe was chosen in 96″ and 90″ sizes. The contract documents required single-pass tunneling as the standard. The contractor elected to use a hand mining process. PSC specified fiberglass manholes as an option, in addition to the concrete manholes used in previous Lubbock deep storm sewer projects.

Route selection for this project was a key element of the design. PSC worked closely with the City of Lubbock and various stakeholders to identify, avoid or adjust for numerous anticipated construction issues. An easement on Texas Tech University property was acquired for a portion of the route, but other portions had to be constructed below roadways, some of which were narrow residential streets. The route passes under and through the sorority and fraternity area on Greek Circle. Concerns for traffic and student safety resulted in contract provisions for scheduling work to avoid busy times in that area and for additional security on the 45-foot trench. The route needed to cross Marsha Sharp Freeway, and more than one location was considered. The best route still had to pass closely between two freeway support piers, and the tunnel also passed under a constructed wetland.

PSC coordinated with the firm selected for construction management services, expediting reviews in order to avoid any delays related to communications.

PSC provided Engineer of Record Services during construction. At that time, PSC converted the design hydraulic and hydrologic model to ICPR version 4 in preparation for final record documentation and model creation upon construction completion.