Water and
Wastewater Planning

Gray Sewerage Extension

GreenPoint provided engineering design, construction administration, NEPA compliance and CDBG grant administration services for the project extending wastewater service to the community of Gray in northern Terrebonne Parish. The project qualified for CDBG Disaster Recovery funding following Hurricanes Gustav and Ike, when much of the area in and around the city of Houma area lost power, resulting in sanitary sewer overflows at the Fairlane Drive WWTP. Further, unprecedented residential and commercial growth in the community required the expansion of wastewater service to meet new demand, as the coastal population shifts toward less flood prone areas.

GreenPoint prepared the CDBG disaster recovery application to fund the project, and prepared the Environmental Review Record documenting NEPA compliance for eligibility. GreenPoint then prepared the design of the project, consisting of the design of a new variable speed 2.5 mgd wastewater pump station, de-commissioning of the Fairlane Drive WWTP, re-routing its flow to the new station, rehabilitation of an existing lift station and the design of over 11,000-ft of new 6-inch and 14-inch HDPE force mains, installed by horizontal direction drilling, tying the consolidated facilities to the Parish’s North Regional WWTP.

St. Tammany Parish Watershed Management Plan

As the Coastal Protection and Restoration Authority sought to evaluate the feasibility of implementing sustainable water quality improvement measures to restore the condition of streams in St. Tammany Parish, GreenPoint, as a subconsultant to Providence Engineering and Environmental Group, was responsible for the analysis and planning of water and wastewater infrastructure needs, the overall financial planning for both drainage and wastewater needs, and development of the necessary GIS data tools.

GIS Development

The analysis required a combination of data describing existing waterways, existing infrastructure, current land use and property lines, and utility customer data, population and projected population growth. Because the available data and GIS databases were not available from a single source, GreenPoint created a new database incorporating the GIS data from the various sources, and structured the data in a usable format for use by other agencies. The completed database addressed the project’s infrastructure and financial planning objectives and was delivered to the Parish to serve as basis for inter-departmental planning.

Water Quality Analysis and

 Planning

To achieve the water quality objectives, GreenPoint was responsible for quantifying the water quality deficit resulting from wastewater infrastructure deficiencies within compromised drainage basins, including over 200 unsewered subdivisions. Using those data in combination with the water quality model results generated by Providence, GreenPoint identified infrastructure improvements that would yield water quality improvement in the Parish’s receiving streams and developed conceptual designs and cost estimates for the implementation of wastewater infrastructure where Providence’s model projected improvements.

Financial Planning

GreenPoint was also responsible for developing a financial model illustrating the terms necessary to achieve a financially sustainable implementation of the developed stormwater and wastewater infrastructure improvements. GreenPoint’s financial model projected the overall planning, design, and construction costs, as well as the predicted costs of ownership, and the necessary revenue and financing terms required for the implementation of a financially sustainable infrastructure program. Using this tool, it was possible to prioritize the needed improvements in terms of pollutant load reduced, cost per customer, and overlap with the Parish’s planning objectives.

St. Tammany Parish Water and Wastewater Consolidation Conceptual Design

St. Tammany Parish has enjoyed a long history of growth, and its growth continues along the LA-1077 corridor, from I-12 north to Goodbee and beyond, where private developers are investing in new residential communities. In addition to planning for this growth, the Parish recognizes the opportunity these new developments offer to begin a new phase of consolidation of water and wastewater systems.

To initiate consolidation, the Parish directed GreenPoint Engineering to prepare a Conceptual Design Report to guide the design and construction of immediate water and wastewater priorities. The objective of GreenPoint’s Conceptual Design was to establish the sequence, method, and budget for consolidating conveyance and treatment of the various water and wastewater service areas in the West St. Tammany Planning Region. The first step was to document the Parish’s planning objectives, including regulatory compliance, level of service, and private and intergovernmental partnerships. GreenPoint also established the existing conditions by creating a GIS inventory of existing infrastructure and delineating existing service areas.

To establish the growth needs, GreenPoint incorporated the planned new developments into the inventory to project future water and wastewater demand. With these projected future conditions, GreenPoint developed a wastewater collection and pumping system model to determine the location and capa-

city of the pumping stations required, and to determine the most cost-efficient and scalable force main network required to convey flows to the planned Goodbee and existing West St. Tammany regional treatment facilities.

The Conceptual Design identifies and scopes the specific capital projects the Parish must implement to meet the new demand, the necessary project sequence, and the estimated costs so that the Parish can initiate land acquisition, surveys, design and financing.