Interim Solution for Regional Raw Water

Prepared for the 2014 NC American Water Works Association & Water Environment Association (AWWA-WEA) Annual Conference by Tony Boahn, PE, Vice President, McKim & Creed, Inc.

Read the full white paper

Abstract

Via the Kings Bluff Raw Water Facility, the Lower Cape Fear Water & Sewer Authority (LCFWSA) provides up to 45 mgd of raw water to the Brunswick County Northwest Water Treatment Plant (WTP), Cape Fear Public Utility Authority (CFPUA) Sweeney WTP, Pender County WTP, and two private industries.

For several years, the Kings Bluff system was challenged by low delivery pressure at the CFPUA raw water meter vault, which is the termination point for the raw water conveyance. This low pressure was caused by increased system demands and competing pressures from a CFPUA-owned raw water supply, and prevented CFPUA from fully utilizing its allocated raw water capacity of 23-mgd.

Long-term projections indicated that a permanent booster station would be needed to meet both pressure and demands in the system, at an estimated cost of $7 million. In lieu of constructing the permanent station, however, the team seized upon the concept of an interim booster pump station that met the following challenges and parameters:

[unordered_list style=’circle’ number_type=’circle_number’ animate=’no’ font_weight=”]

capable of meeting immediate and near-term customer needs,
operational only 3-4 months per year (summer peak months),
located on remote site with minimal electrical capability,
SCADA/telemetry control for semi-automated operation, and
configuration that allowed for future permanent booster pump station.

[/unordered_list]

Ultimately, the interim booster station was constructed for $1.5 million, resulting in significant savings as compared to construction of a permanent booster station estimated at $7 million. The interim facility utilizes diesel-driven pumps acquired via rental agreement with a major pump supplier who provided all installation and maintenance of the pumps, which further reduced operating and maintenance costs. The pumps are rented only during the peak summer period and are then removed at the end of the season. With the interim booster station and peak-season pump rental, LCFWSA:

[unordered_list style=’circle’ number_type=’circle_number’ animate=’no’ font_weight=”]

eliminated capital costs for electrical upgrades as well as future utility costs,
saved significant costs in comparison to full purchase or year-round rental,
minimized operation and maintenance needs,
provided 29-mgd capacity to meet interim pressure and demand needs,
provided permanent infrastructure for a future permanent booster pump station,
furnished semi-automatic operation through a SCADA-controlled system, and
created an emergency interconnection with the CFPUA-owned 30-inch raw water main.

[/unordered_list]

The final project provided a creative and cost-effective solution to meet the interim demands and delivery pressures of LCFWSA customers. This presentation will provide an examination of the alternatives evaluated and the final constructed project.