Tyler Brennan
Jessica Fegely
Andrea Fiala
Anthony Knesis
Angela Le
The project has been conducted under the guidance of the faculty advisor, Matthew VanKouwenberg.
---------
Abstract
The goal of this project is to build a first-flush diverter, which is to be used as a piece in a rainwater collection and filtration system. In collaboration with Drexel University’s chapter of Engineers Without Borders, the flush diverter will be implemented into the rainwater filtration system used in Miramar, El Salvador, and, as such, must be constructed in a way that is sustainable for the community. Major tasks of this project include creating a timeline, calculating necessary measurements in regard to the size of the flush diverter, creating and testing a working prototype of the device (Sustainable Rainwater-Harvesting Flush Diverter), and composing a final report reflecting upon the project’s progress and success. Technical challenges expected for this project include ambiguity of data received from Miramar, prototype material research/acquisition, and prototype construction. The final deliverables for this project are to be a detailed design and physical prototype of the flush diverter, the structural support necessary to attach the diverter to a home, and an AutoCAD assembly of the flush diverter design along with a blueprint of the entire system on a theoretical surrogate home, including the collection system and water delivery mechanisms.
1 Introduction
The town of Miramar is a mountainous village of about 200 residents in the municipality of San Francisco Menéndez, El Salvador, which suffers from a severe potable water storage problem [1]. The townspeople currently gather water from ground wells contaminated with bacteria, causing health problems among the villagers. Because these water sources dry up during the summer months, the town also struggles with the ability to safely store collected and purified water for long periods of time. For this aim, the Drexel University chapter of Engineers without Borders (EWB) has been investigating methods of providing sustainable sources of clean water, including the implementation of community-maintained biosand water filters and rainwater-catchment systems. This drive to collect all sources of clean water extends especially to rainwater, due to its relative purity and immediate suitability for drinking. However, due to dirt and other microorganisms that grow on roofs, the first gallons of rain that fall during a storm are contaminated and should not be collected. After a certain capacity, however, the roofs are essentially clean and subsequent rainfall can be collected for drinking purposes. A rainwater first-flush system can help divert a certain amount of contaminated water for use in non-drinking purposes while separating the clean water for use by the residents of the village. This project seeks to construct a working prototype of a first-flush system using sustainable materials available to the people of Miramar in the hope of improving their clean water supply and reducing the risk of waterborne illnesses.
1.1 Learning Objectives
1.1.1 Major Tasks
The major tasks of this project, in chronological order, will be to create a timeline, conduct research, finalize calculations, build the prototype, create the AutoCAD designs, test the prototype, and write the final report for the project. The timeline will be based on a 10-week schedule in the form of a Gantt chart. Research will include looking up information about existing prototypes, available in-country materials, and home designs in Miramar. Measurements and calculations relating to roof design and rainfall will be used to finalize the prototype size and structure. The prototype of the flush diverter will include both the diverter and its support system.
1.1.2 Technical Challenges
The greatest technical challenges for this project will be building the prototype of the flush diverter and finding suitable methods of supporting it once attached to a home. Building the prototype may be a challenge because the goal is to create a design that is sustainable for the community members of Miramar, so the prototype should only be constructed using materials available to the village. Additionally, support is an issue because large amounts of rainwater fall in Miramar during the rainy season. As a result, large volumes of water will be entering the flush diverter regularly. A support system for the diverter must also be constructed using sustainable materials.
1.1.3 Desired Outcomes
The main desired outcome of this project is to build a working prototype of the Sustainable Rainwater-Harvesting Flush Diverter. If successful, another positive outcome of this project will be the implementation and installation of the flush diverter design to the gutter systems on the homes in Miramar. Ultimately, this will improve the ease of harvesting drinkable water for the citizens of Miramar, therefore improving the health and quality of life of the village’s citizens.
2 Deliverables
The main deliverables for the project include a finalized design for the first-flush diverter based on materials research, and a physical prototype based on this design. To produce a useful design, a compilation of data pertaining to the houses and rainwater that needs to be diverted from a typical home will be provided. An AutoCAD assembly will be produced that includes not only the design, but the surrogate house that will hold the rainwater system. Within this assembly, multiple parts will be provided, such as the collection apparatus, the flush diverter, and any delivery mechanisms to be included after the impure water has been diverted. Once the computer-aided design of the flush diverter has been completed, the next step will be to construct a physical prototype of the flush diverter mechanism. This device will not only include the diverter and collection tank, but also the structural support necessary to attach the system to the house. To represent the functionality of this device, a demonstration using water might be used.
2.1 Detailed Design of Rainwater System with Materials Available to Miramar Residents
As aforementioned in the introduction, the final product of this project is the construction of a prototype Sustainable Rainwater-Harvesting Flush Diverter. In order to do so, much research will be needed to gather information about the houses in the village of Miramar where the devices are to be implemented. Information about the houses such as surface area of the roofs and the scaffolding of the house will be crucial in determining the flush capacity (the amount of water that contains excessive contaminants) to be collected before the stream of water can be diverted to a collection container. Analysis of the support system of the roofs (either cement columns or wooden beams) will determine how the flush diverter will be constructed and mounted to the gutter system. After knowing these parameters, a prototype of the first-flush diverter can be created using a 3D modeling software such as AutoCAD or Autodesk. This software is crucial for the designing process as the prototype design can be easily modified if necessary. The model can then be used as a reference to build the tangible prototype.
2.2 Prototype of Sustainable Rainwater-Harvesting Flush Diverter
The prototype of the SFRD is to be constructed in a way that would be realistic to the community members of Miramar, El Salvador. Keeping this in mind, the prototype will be constructed from materials that are available both in the United States and El Salvador, such as common plastics, PVC pipes, and bamboo. Bamboo which is easily accessible in Miramar, can be used to create the system of support for the flush diverter, as well as attachment to the homes in Miramar.
3 Technical Activities
3.1 Flush Diverter Research
Before any specifications can be made for the construction of the rainwater first-flush diverter, design constraints must be established based on the local conditions in Miramar and the materials available. Information from the Drexel University chapter of Engineers without Borders will be critical in learning about the weather trends for the town of Miramar and the adaptation of the rainwater flush diverter to the village’s living conditions.
3.1.1 Rainwater Data Research
Because the flush diverter must collect an amount of water proportional to the duration of the rainstorm and the size of the roof, rainwater catchment systems localized to Miramar must take into account the monsoon-like conditions of the El Niño weather pattern by operating in accordance with trends for rainfall over several years. The average size of the roofs must also be measured to determine the size of reservoir for the first-flush itself.
3.1.2 Roof Contamination Research
By separating the contaminated first-flush from the main body of a rain event, it is hoped that the collected water can be used immediately for potable purposes, given the relative purity of rainwater. However, based on the type of material used on the roof, some rainwater may not be pure enough for drinking immediately after collection. For example, ceramic roofs may require more flush volume than sheet metal roofs. Additionally, if some roofs contain mold or other organisms fused to the material of the roof, contingency plans should be included with the design to account for such eventualities. Through EWB-Drexel member testimony, location images and Google Earth, the size and composition of average roofs should be able to be determined and recorded.
3.2 First-Flush Diverter Design
After the research into the localized conditions of first-flush diverter use is finished, the official design of the rainwater catchment device can be drafted. Although designs already exist for the construction of first-flush diverters, they must be adapted to the list of available materials and the specific circumstances of device placement, which will vary based on the specifications of roof size and rainfall data measured.
3.2.1 Implementation of Materials
One unique aspect of the Engineers without Borders mission is their dedication to the long-term sustainability of their projects. As such, all improvements are required to be constructed from readily-available local materials, in this case, those that are found in Miramar or are provided by the mayor of the municipality of San Francisco Menéndez. Given that EWB-Drexel University has a history of constructing filters in the community, senior members would be knowledgeable about the exact list and type of materials from which the flush diverter can be constructed.
3.2.2 First-Flush Diverter Support
Given the high-volume rain events of Miramar and the sectional division of the roofs, the first-flush diverters will likely have to hold a significant volume and weight of water. As such, a nontrivial task will be to design a support system for the prototype for each house, utilizing only the list of sustainable materials already available for first-flush diverter construction.
3.3 Prototype Construction
Once the materials and official design have been determined and finalized (through computer-aided design or otherwise), the final major task in the project is the actual construction of the first-flush diverter itself.
3.3.1 Confirmation of Storage Space
Before any work can begin on the assembly of the first-flush device, it must be confirmed that there is sufficient space to store the prototype outside of team meetings. The Drexel University chapter of Engineers without Borders currently has a partnership with the Concrete Canoe organization to allow for storage of its biosand filter molds and other materials; it is hoped that this area can also be used to store the prototype. Else, plans must be made to store the assembly in another location, or it must be stored in one of the team member’s personal residences.
3.3.2 Acquisition of Materials
Although volunteer teams working in Miramar have their materials delivered to the worksite courtesy of the mayor of San Francisco Menéndez, materials must be purchased and collected by individual members of the design team, with or without financial assistance from EWB-Drexel University. As such, plans must be made during the project to either coordinate travel to and from a construction wholesaler, or make online purchases of the necessary materials to proceed with prototype construction quickly and efficiently.
3.3.3 Construction, Testing, and Modification of Flush Diverter Prototype
The main task of the project is the construction of a working prototype for a sustainable rainwater-harvester flush diverter. As such, much consideration and testing must be given to the proper design and function of the device and its support systems. It is hoped that the catchment system can be tested under rain event-like conditions to verify the functionality of the flush diversion parts and make improvements and modifications, if necessary.
4 Project Timeline
Table 1: Flush Diverter Project Timeline
Week
| ||||||||||
Task
|
1
|
2
|
3
|
4
|
5
|
6
|
7
|
8
|
9
|
10
|
Literature Study/Research
|
x
|
x
|
x
| |||||||
Design Development
|
x
|
x
|
x
|
x
| ||||||
- Analysis of Available Materials
|
x
|
x
| ||||||||
-Finalizing Methods of Support
|
x
|
x
| ||||||||
-Drafting Blueprint/CAD Diagram
|
x
|
x
| ||||||||
Acquisition of Materials
|
x
|
x
|
x
|
x
| ||||||
Prototype Building
|
x
|
x
|
x
|
x
|
x
| |||||
Testing/Modifications
|
x
|
x
|
x
|
x
| ||||||
Final Report Preparation
|
x
|
x
|
x
|
x
|
x
| |||||
5 Facilities and Resources
Several resources are available in-country and online for the development of our rainwater flush diverter project. In regard to data and research, the Drexel University chapter of Engineers Without Borders (EWB) should have relevant data about rainfall and roof size from semi-annual trips to the region. This information is published on an online drive and is available to all members of the project, who are also members of EWB-Drexel University. In general, there is publicly available information about similar projects on the Engineers Without Borders USA website, which can be useful when researching general designs for rainwater catchment systems and proper measurements for the capacity of the first-flush. Several resources are also available on-campus to facilitate the physical construction of the prototype. In association with the Engineering Department at Drexel University, the Innovation Studio work area is available on Mondays from 9AM to 5PM for open design. Additionally, EWB-Drexel University has ties with the Concrete Canoe organization to obtain a storage space for rainwater projects. Finally, the Drexel University Machine Shop could also prove useful during prototype construction tools and resources, especially if wooden supports must be especially made to support the weight of the flush diverter.
6 Expertise
In order for the prototype to be built successfully, expertise will be required in the following areas: operating machinery, collecting data, and 3D modeling. Knowledge of the geography, available materials, and architecture of the houses in Miramar will be critical in the design of the prototype. As members of EWB-Drexel University, each of the group members has a general understanding of the Miramar project goals and progress. However, because the design group creating the prototype has never travelled to Miramar, there will be heavy reliance on the information gathered first-hand by members of the Miramar Travel Team in EWB-Drexel University as well as the documentation available online in the group archives. This is important for the building process if the prototype is meant to be sustainable, that is, if repairs can be made in-country with the materials that are available to the villagers. The best method of creating the prototype will be using a modeling software such as AutoCAD. Each member of the group has experience with both 2D and 3D computer-aided design, skills that will be important in creating images of the design for the flush diverter. An additional set of hands-on skills are also required to efficiently build the prototype of the flush diverter. In order to construct supports for the catchment device, it may be necessary to use the Drexel University Machine Shop. As such, one or more group members will need to undergo training before being able to use the various power tools available.
7 Budget
All materials are assumed to be purchased by the group members, unless EWB has the materials in their stock and are willing to donate. While the individual materials used will depend upon the research into sustainable materials available in El Salvador, including wood, bamboo, and PVC pipe, the projected costs to construct the different segments of the flush diverter can be estimated.
Table 2: Design Budget
Category
|
Projected Cost
(United States)
|
Projected Cost
(Miramar, El Salvador)
|
Water Diverter Mechanism
|
$30.00
|
$10.00
|
Collection Tank
|
$60.00
|
$20.00
|
Connection/Support System
|
$30.00
|
$10.00
|
TOTAL
|
$120.00
|
$40.00
|
7.1 Water Diverter Mechanism
The diverter mechanism will allow the contaminated water to flow from the gutters to the Sustainable Rainwater Flush Diverter until the mechanism fills to the calculated water level in which a sufficient amount of contaminants are “flushed” from the roof. A ball within the device will rise with the water level. Once the water level reaches the calculated point, the ball will rise to block the pipeline that feeds the contaminated rainwater into the device and the water will be diverted to a new pipeline that will direct the cleaner rainwater to flow into a water-harvesting tank.
7.2 Collection of Contaminated Water
The device will hold the contaminated water from the first-flush rainfall that flowed from the gutters. The amount of water to be collected (and the dimensions of the device) will be calculated in the ensuing weeks from the research that is conducted. The diverter will be able to be emptied in between rainfalls for removal of the contaminated water. This ensures that the contaminants will not grow within the device and that during the ensuing rainfalls, the contaminated water will be collected in the device and not into the collection tank with the clean water.
7.3 Connection & Support System
The rainwater harvesting device will be mounted to the house. This attachment must be able to withstand the weight of the device and the calculated amount of rainwater. As a result, the device will most likely be placed on the ground attached to the gutter-system of the houses which vary from house to house. Therefore, proper planning and research must be conducted in order to create an attachment system that will be able to be applied to all house-structures. The attachment will be connected to the gutter through the wooden beams that support the awning structures that protrude from the rooftops.
8 References
[1] W. G. Char et al., “Pre-Implementation Report - Miramar,” Engineers without
Borders - Drexel University Chapter, Philadelphia, PA, Rep. 525, 2015, p. 12.