As part of the budgeting and planning of priority needs at the Williams WWTF, the largest wastewater treatment facility within the system, the Mobile Area Water and Sewer System (MAWSS) commissioned GreenPoint Engineering to perform a study of the feasibility to convert the facility’s secondary treatment process from the current high-purity oxygen (HPO) system to conventional diffused aeration. By converting to conventional aeration MAWSS would have the ability to reduce effluent ammonia levels below current and even projected future treatment limits, and also gain the benefit of a more resilient and energy efficient process. The feasibility study concluded that a conversion of the existing HPO system to aeration is possible through the construction of additional secondary treatment volume and the addition of new blowers and fine bubble diffusers. This study also projected that the conversion would generate a net operation and maintenance costs savings that would exceed the capital cost savings over a 20-year life cycle.
GreenPoint Engineering evaluated Plaquemines Parish Government's nine elevated water storage tanks, summarizing needs in a capital plan and preparing engineering design for the needed improvements. Plaquemines Parish is located at the mouth of the Mississippi River as it enters the Gulf of Mexico, encompassing both banks just downriver of New Orleans. The water distribution network consists of two separate, linear systems on either bank of the Mississippi river. This configuration of the system poses additional logistical challenges in assessment and repair of the towers in order to maintain water quality and redundancy. GreenPoint Engineering developed an assessment protocol in coordination with Parish officials that achieves the assessment and planning goals while maintaining public health and safety.
As the Coastal Protection and Restoration Authority of Louisiana 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 under Providence Engineering and Environmental Group, was responsible for the analysis and planning of wastewater infrastructure needs, the overall financial planning for both drainage and wastewater needs, and development of the necessary GIS data tools. GreenPoint's financial model also predicted overall costs and revenue requirements for the implementation of a financially sustainable infrastructure program.
The analysis required a combination of data describing existing waterways, existing infrastructure, current land use and property lines, in addition to 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 in a usable format for the planning uses of other agencies. The completed data base 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.
GreenPoint was also responsible for developing a financial model illustrating the conditions 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.
To satisfy contractual agreement between Veolia Water of North America and the Sewerage and Water Board of New Orleans, GreenPoint Engineering established the initial condition of the Board's wastewater treatment system assets, establishing the baseline conditions as Veolia assumed operation, maintenance and management responsibility. A secondary goal of GreenPoint's Initial Condition Assessment was to prioritize needs with respect to deficiencies in support of the development of a 10-year capital improvement program.
GreenPoint performed inspections of the facilities and documented the assets using a standardized format geared toward assessing condition, and meeting the ultimate goal of prioritizing needs. The data collection methodology followed the standardized inspection and evaluation process established by Veolia, designed to limit subjectivity and drawing exclusively on field observations. The collected data reflected the physical condition of each asset with respect to its structural, mechanical and electrical components as well as overall degradation. The inspections also rate each asset with respect to functionality.
To arrive at each asset’s criticality, GreenPoint developed a screening tool based on two scored factors: the probability of an asset failing and the consequence of a failure. Because the likelihood of an asset failure is primarily based on the asset’s condition, the probability of failure is derived from the condition ratings assigned during the field inspections. As system redundancy also contributes to the probability of a failure, those systems that have redundancy either in the form of parallel systems or backups are differentiated from those that do not in the probability of failure ratings. The consequence of an asset’s failure also informs criticality, as failures that compromise either safety or compliance are of greatest concern to operations. Therefore those assets that directly impact safety or compliance are given a higher consequence of failure score.
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