The Indigenous community of the Grand Caillou/Dulac Band of Biloxi-Chitimacha-Choctaw is located Southwest of New Orleans, just off the bayou of the Gulf of Mexico. Due to their location, they are often hit with the worst of the hurricanes causing flooding, power outages, loss of municipalities, and extensive property damage. Even past the initial disaster itself, large sections of the population are often left without a safe place to stay or access to water or electricity while the community recovers. To meet this need the Grand Caillou/Dulac Band of Biloxi-Chitimacha-Choctaw is partnering with the Purdue EPICS chapter of Engineers without Borders, and the Community Engineering Corps to develop a hurricane resiliency and cultural center.  

 

This center will function as a hurricane recovery center with emergency supplies and housing, as well as a cultural center to allow the community to come together for educational purposes and entertainment. The general occupancy is assumed to be three staff members and about 20 visitors daily, but the building will have a maximum capacity to accommodate approximately 500 people for events held at the center or when recovering from a disaster. After a hurricane, supplies including tents, food, and bathroom facilities will accommodate about 70 families totaling an average of 280 individuals.  

 

At our partners' request, one of the main design constraints is to have the community center be as environmentally sustainable as possible. Our goal in relation, therefore, is to construct a building capable of having general water needs, such as sinks, toilets, showers, laundry, and dishwashers, supported by rainwater collection rather than municipal sources. The structure will be connected to municipalities services to supply the fire suppression system; however, the community should be able to live comfortably off the grid for day-to-day activities and during a disaster recovery period of one month. In that one-month period, there must be enough water available to support the use of water in the sinks, toilets, showers, and laundry for the anticipated 280 individuals. The use of dishwashers will not be included as this was determined to be a non-vital use and was not requested by our clients to be included.  

 

This goal comes from our partners experiencing a lack of access to municipal water in the recovery period after recent hurricanes. Flooding and storm surge damage caused a delay in the re-establishment of public sources of treated water that lasted far longer than anticipated and as a result many of those in rural areas were cut off from this vital recovery resource. 

 

With this sustainability goal in mind, the senior design team is researching innovative ways to improve the water efficiency of the center. The rainwater system should include catchment, storage, filtration, and distribution. Stored rainwater will be distributed throughout the building and will be used in toilets, sinks, showers, dishwashers, and laundry. The excess water, if there is any, can be used to irrigate the site. In addition to water collection and reuse the design will include the most water efficient appliances currently on the market to reduce the amount of water being used overall.  

 

The preliminary scope of the design included a Greywater reuse system. This design would involve greywater collected from within the building; from sinks, showers, dishwashers, and laundry, being cycled through a filtration system and reused until it qualifies as black water. Black water has been contaminated by human waste or other non-biodegradable contaminants and would be sent to the site's septic system. This aspect of the scope was ultimately disregarded as this would necessitate a separate plumbing system to run through the building as grey water would contaminate the treated rainwater; and we were advised by our advisors in the Engineers Without Borders EPICS team to focus on the rainwater system to ensure a realistic scope.  

 

The overall goal is to design a contained water system to minimize waste and ensure the community has access to water separate from municipal sources in case of an emergency. This scope has been further specified to three main sections: Collection, Storage and Filtration, and Distribution. Each member of the senior design team selected a section to focus on.  

 

As the head of the Storage and Filtration section it is my goal to ensure the water captured from the roof will be stored in such a way as to ensure the consistent quality of water and in accordance with federal and local regulations. To do this a sufficiently sized storage tank configuration must be established to store enough water to be used in the case of a hurricane, but not so much that there is an excess of standing water in the tanks. A filtration system must also be integrated into the design to treat the water to EPA drinking water standards, as it is being used in bathrooms and kitchens. We will be referencing the National Primary Drinking Water Regulations (NPDWR)1 to ensure the water being supplied is safe for human consumption.  

To estimate the size of the storage tanks, the water usage was calculated for typical daily use and for use in a disaster recovery event. The summary of these calculations can be found in table 1 and a more detailed explanation with included assumptions can be found in figure 1 and figure 2 of appendix A. From these it was decided to have a multistage storage system to accommodate the difference in water usage for typical and recovery scenarios. There will be two 5,000-gallon storage tanks to allow for the estimated recovery use amount of over 9,000 gallons per day. The choice of two smaller tanks rather than 1 was made to allow for a smaller total failure risk. If one tank is damaged the system will still survive, allowing for individual maintenance on the tanks. The water will then be treated and stored in a 500-gallon day tank before being pumped into the building for use.  

 

The treatment of the water will happen in three stages, a micro filter to remove solid particulate, an Ultraviolet (UV) filter and finally a chlorinator to remove bio contaminates. The inclusion of a UV filter before the chlorination is intended to reduce the amount of chlorine needed to maintain a sanitized water supply. The EPA sets a limit of 4 milligrams of chlorine residual per liter of water; by including a UV filter we can use set our residual to be about 2 milligrams per liter which is well under the regulation while achieving sanitized water. The amount of chlorine needed to reach a concentration of 2 mg residual was calculated to be 75.7 mL of 5.25% chlorine bleach, the detailed calculation can be found in figure 3 of appendix A.  

 

Over the coming semester I will be completing various calculations regarding the treatment of the water as it is moved to the day tank, including pressure requirements and comparing contaminate levels after being passed through proposed treatment systems. I will also need to calculate and consider the target flow rate exiting the treatment system to ensure it is not causing a delay in available water supply. Additional assumptions such as average replenishment rate will be determined and stated at that time. These replenishment rates will be checked by a third party source by week 4 of next semester.  

 

The culmination of this project will be a formal design presented to our partners and the various industry professionals overseeing this project. This design will include all calculations, product recommendations, and product configuration to meet the water needs of the community while maintaining the standards set in the NPDWR. This formal design will be an implementable proposal given to our professional team for their consideration in the future build, however we will not be delivering a physical product as the community center is scheduled to be built in the next 5 years.