Document 523 ALTERNATIVES ANALYSIS REPORT

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1 Document 523 ALTERNATIVES ANALYSIS REPORT CHAPTER: COUNTRY: Sierra Leone COMMUNITY: Baoma PROJECT: 4-Seater VIP Latrine PREPARED BY Matthew O Boyle and EWB PSU Project Committee Submittal Date ENGINEERS WITHOUT BORDERS-USA Engineers Without Borders USA. All Rights Reserved Page 1 of 29

2 Alternatives Analysis Report Part 1 Administrative Information 1. Contact Information Name Phone Chapter Project Leads Matt O Boyle mio5027@psu.edu PSU President Meghan Fisher mef234@psu.edu PSU Mentor #1 Rich Kercher rkercher@gfnet.com PSU Mentor #2 PSU Faculty Advisor (if John Lamancusa JSLME@engr.psu.edu PSU applicable) Health and Safety Officer Student 1 PSU Assistant Health and Safety Officer Student 2 PSU NGO/Community Contact Mohamed Khalil moselkha@yahoo.com Sierra Leone Education Lead Student 3 PSU 2. Travel History Dates of Travel Assessment or Implementation Description of Trip 7/17/10-7/27/10 Assessment Sanitation 3. Project Location Longitude: N Latitude: W Engineers Without Borders USA. All Rights Reserved Page 2 of 29

3 Alternatives Analysis Report Part 2 Technical Information 1. INTRODUCTION The Penn State University EWB Chapter, still in its first year of existence, is a very young chapter to say the least. However, after a successful assessment trip this past summer, the possibility of carrying out a successful implementation trip this upcoming May has become within reach. Last spring, we accepted a project in that had been set up and requested by a local NGO, EWB Sierra Leone, established by Mohamed Khalil. Mr. Khalil is a registered Civil Engineer who owns and operates his own engineering company. He established EWB Sierra Leone in the hope of being able to help any and all that he can. Mr. Khalil informed us of a Christian school that had been recently established in the small community of Baoma that was running off of the help of a few very dedicated local volunteers. They established the school as the first step towards educating the local children and helping them live better lifestyles. The school is in dire need of help due to its lack of funds and appropriate engineering knowledge. Our proposed project is to implement a sustainable and sanitary 4-Seater Dual Pit VIP latrine for the school students and faculty to use. The purpose of this project is to improve their current sanitation situation as well as to instill better, healthier policies of cleanliness. We hope that, with our latrine serving as a model, these policies will spread beyond the school and throughout the rest of the village. In the following report, we will describe, analyze and compare the following five alternatives for a latrine design using our assessment trip data, sound research and logical comparison methods. We will conclude our report by choosing one of these design options as our preferred alternative. Five alternatives to be analyzed: 1. Pit Latrine 2. VIP Pit Latrine 3. Dual Pit VIP Latrine 4. Pour-Flush Latrine 5. Composting Urine-diverting Dry Latrine 2007 Engineers Without Borders USA. All Rights Reserved Page 3 of 29

4 2. PROGRAM BACKGROUND Baoma: a small community with over 600 inhabitants located near the capital city of Freetown. They lack water and sanitation facilities in the school as well as the community. The students use the bush as a latrine which not only extremely unsanitary but is also very demoralizing specifically for the girls. The head founder of the school would like a VIP latrine that would provide privacy and cleanliness to the school students and faculty. This would be very beneficial for hygiene as it is lacking in the village. Improved sanitation and hygiene practices are a very good stepping stone for the villagers to live better and healthier lifestyles. As seen in many underdeveloped regions around the world, disease and sickness are spread through poor sanitation conditions. These problems are very prevalent in the community and need to be drastically improved as seen from the results of our health assessment. Providing the VIP latrine will give pride to the students with a strong start to sanitation and hygiene. With correct practice, illnesses should be reduced and overall health should improve. One of the first items to address is understanding the customer s needs and requirements. We need to know what need is most important for the community so that we can plan and design our project around that. While on our Assessment Trip we held a community meeting with the chief and queen as well as other village heads and members. Here we discussed our results and opened up the forum for all to speak. We had great feedback on what the community really values and views as important. The biggest issues were helping to aid in education, water abundance and quality, and health care facilities. Our project would fall in the education category and we great support from the members of the village. They believed that if you start sanitation practices at a young age there will be great change in the future. The current sanitation situation is very poor. There are very few latrines throughout the village and they are all personally owned and maintained. All without latrine facilities are forced to go outside wherever they can. We found evidence of this very close to water sources throughout the community which contaminates the local sources. We will have to educate the school children on proper sanitation methods. We were excited to have the support of the village so that we could build a strong and trusting relationship with them. We now understood the problem and moved on to addressing some of the data we acquired from our trip. After traveling to Baoma on our Assessment Trip we have a very good understanding of the sanitation problem and necessary design constraints for an implemented latrine. The school is run by four volunteer locals who oversee approximately 60 children. With these numbers we will plan to design and construct a 4-Seater Dual Pit VIP Latrine that has male and female stalls. The school structure itself is built right next Martin Simbo s house, the school headmaster. The proposed latrine structure would be built directly behind Mr. Simbo s house as seen in Figure 7 in the appendix. This location is the only possible site for our proposed design due to limited property size and the close proximity to a surface water source. Figure 7 and 8 show the location of the stream which is approximately 30 feet from the proposed site. Percolation Tests were run in the proposed project site area revealing a high rate of percolation, draining at a rate of approximately 4.5 inches/hour. This information is pertinent because of our proximity to the water source. We will use these constraints to help the decision and design process Engineers Without Borders USA. All Rights Reserved Page 4 of 29

5 3. DESCRIPTION OF COMPARISON METHODOLOGY One of the most important parts of the latrine designing process is the selection of the right latrine that will best suit the community and their needs. This is crucial because it has to be a design that can be sustained by the community. If the needs of the community are not taken into account the success of the project will be compromised. In order to select this appropriate design you need to compare the designs to one another. We decided to use numerical and weighted scoring matrices as one of our methods. What these matrices do, is they take into account a list of specified factors that are involved in a latrine project. The numerical scoring matrix gives us a specific number value for the effectiveness that each latrine type has with each of the factors. The weighted scoring matrix shows us the importance of each factor compared to the other factors which signifies which factors are most crucial for a latrine project. The results of these two matrices are computed together to give us a final matrix which has numbers designating the top latrine choice. First, each design was rated in each category of comparison with a number one through five, with five being the best and one the worst. These ratings were entered into the numerical scoring matrix (Table 1). The factors which were taken into account include the lifetime of latrine, cleanliness/odor, cost/amount of materials, effects on groundwater, maintenance, and social acceptability. The lifetime of latrine comparison factor includes how long the latrine can be used and the long term operating issues associated with each latrine design. The consideration of cleanliness takes into account the sanitation importance and feasibility of keeping the latrine clean in the setting. The cost/amount of material takes into account the cost, construction of the facility, and availability of materials. Effects on groundwater are a big concern when considering the design. The effect on groundwater is one of the ways in which sustainability was incorporated into comparison. The maintenance of the latrine, looks at the energy and time needed to successfully manage the latrine structure. In order for the project to be successful we must have the support of the community and its members which is rated by social acceptance. After the numerical scoring matrix was setup, another matrix was used to find the weight factor for each comparison category. Some of the comparison factors were more important in picking the preferred design than others; the weight factor determination matrix (Table 2) was used to determine the importance of each factor. In this matrix, the importance of each category is individually compared to every other category. If one category is more important than another, the more important one is given one point and the less important one is given zero points. After they have all been compared to one another, the totals are added up and a percent value is given to each category. These percent value are the weight factors. The weight factors are then multiplied by the score from the numerical scoring matrix and these weighted values are entered into a new matrix, the final weighted matrix (Table 3). Each design s scores are then added up and the total scores indicate which design is most appropriate for our project. Other factors have been taken into account that were important to the design but were hard to incorporate into the scoring and weighing matrices Engineers Without Borders USA. All Rights Reserved Page 5 of 29

6 4. DESCRIPTION OF ALTERNATIVES 4.1 Pit Latrine A pit latrine is a lined pit below the toilet that would collect the waste from the above latrine. It would be lined with brick, concrete, or any material would be easily and readily available. When the pit is full, there are several options for emptying it. It can be pumped via a sewer system, but this idea is probably not feasible considering the location in which we are going to be implementing it. It can be filled with soil and a tree can be planted on top of it. This option, however, would end the lifetime of the pit. The pit should be placed at least 30m from groundwater and drinking water to protect from the possibility of water contamination. Similarly, the pit latrine should not be placed in any area that is prone to heavy rain or flooding, as this could cause the pit overflow. odor would be a problem with the pit design, as the only avenue for the odor to leave the pit is through the toilet seat. Pit latrines, because of their simplicity, are have moderately low cost. It is also very simple to build and use. Almost no maintenance is necessary. Figure 1. (Side View of Pit Latrine) (Tilley, Elizabeth, Christoph Luthi, Antoine Morel, Chris Zurbrugg, and Roland Schertenleib. Compendium of Sanitation Systems and Technologies. Rep. EAWAG. Print.) 2007 Engineers Without Borders USA. All Rights Reserved Page 6 of 29

7 4.2 Ventilated-Improved Pit Latrine A VIP latrine is a modification of the traditional pit latrine. The pit is lined with bricks or concrete to give support to the structure. It is recommended that the depth of the pit be at least 3 meters deep. It can have either an open bottom which allows for liquids to seep into the ground or it can be fully lined and pumped out when filled. The structure can hang over the pit and a door can be placed so that it is easy for the pit to be emptied. The door should have a tight seal, to keep the odor to as little as possible. Open bottom designs are suggested to be 3 meters from the water table. Housing for the above ground section can be made out of local materials that are available. In the VIP latrine the entrance is positioned so that it faces a prevailing wind. There is a gap above the door so that wind can enter, travel down through the opening to the pit, and then up through a ventilation pipe to a point about 50 cm above the structure. The opening above the door should be at least 3 times the area of the vent pipe and if designed properly this should significantly reduce the odor resonating from the pit. It is important to have a door that closes by itself or someone checking to make sure that the door is closed, to keep the inside of the structure as dark as possible. Flies are attracted primarily to the top of the structure where the odor exits though the pipe because of the light. Those that do get in try to escape through the brightest part of the latrine which is the vent pipe and are trapped and unable to escape due to the netting. This works very well if the inside of the latrine is kept dark. There is very little maintenance involved with the VIP latrine. The only maintenance involved with the VIP latrine is to make sure the structure is dark and there are no other openings besides the opening the air flows through. It is recommended that you check the netting at the top of the vent pipe and pour water down the pipe once a year. The biggest part of the maintenance would be to pump out the pit depending on how big the pit is depends on how often the pit will need pumped. The bigger the pit the longer the lifetime of the latrine, but if the pit can be pumped the latrine can last for as long as needed Engineers Without Borders USA. All Rights Reserved Page 7 of 29

8 Figure 2. (Side View of VIP Latrine, directional air ventilation) (Tilley, Elizabeth, Christoph Luthi, Antoine Morel, Chris Zurbrugg, and Roland Schertenleib. Compendium of Sanitation Systems and Technologies. Rep. EAWAG. Print.) 2007 Engineers Without Borders USA. All Rights Reserved Page 8 of 29

9 4.3 Alternating Twin-Pit VIP Latrine The Dual VIP employs many of the same virtues of the normal VIP, the difference being that two pits are constructed, as opposed to the normal VIPs one pit. The Dual VIP is built by digging two pits which are then lined with brick or concrete along with a plastic to prevent leeching into groundwater. The main difference in the constructing of the Dual VIP in comparison to the VIP is the construction of two pits at the time of implementation as well as necessity of developing a covering for the pit not in use as a safety and odor prevention technique. The superstructure is the same as the VIP with a ventilation pipe rising about 50cm above the superstructure. The structure should be made to face the prevailing wind as to reduce odor from the pit. There is a slight modification in the base of the latrine where you need two holes for ventilation pipe when the in-use pit is switched. The superstructure should also be designed so that it covers the entire base of the two pit system or so that it is sturdy but can also be moved to the second pit when the first pit becomes full. This allows the first pit to compost while the second pit is in use. After a year the waste from the first pit can be safely shoveled out to be used as compost or a tree, garden or bush can be planted on top of the first pit. Figure 3. (Side View of Alt.-Twin Pit VIP Latrine) 2007 Engineers Without Borders USA. All Rights Reserved Page 9 of 29

10 4.4 Pour-Flush Latrine A pour flush latrine has a pan with a water seal, a conduit partially filled with water. This pan is connected to a pipe which leads into a pit. Excreta are deposited in the pan, and the wastes are flushed using two to three liters of water. Some of the water remains in the pan, preventing odors, mosquitoes, and bug attraction. The wastes will go into the pit and will later biodegrade. The use of two pits is often used and recommended. While one pit is in use the other can be used as an alternative pit once the first pit is full.this allows one pit to degrade more while the other pit is in use. This method decreases the amount of maintenance needed and can allow for the wastes to be removed manually; otherwise wastes would need to be pumped out of the single pit It is advised for the latrine to be placed on a slightly downhill location to prevent any leakage into structures. Water can also infiltrate the soil easily, so extra caution is needed when building the latrine and its location. It should be a safe distance (30 meters) from groundwater source to prevent groundwater contamination.it is also recommended that the pit is slightly above the ground to prevent rain water from entering the latrine. The other materials required for the latrine are two to three liters of water to be used after each use. A grey water system or other method of refilling the water supply will need to be implemented. This is a factor that needs definite consideration when deciding which latrine to build. However, there are some definite advantages to a pour flush latrine. It is more hygienic, easy to clean and maintain, effectively reduces odors and odors, and easy and inexpensive to build. Jeff Chaplin designed what he calls an easy latrine. This pour flush latrine has been implemented all over Cambodia. It has greatly impacted the community, and thousands of latrines have been built because of his design. His designs is very easy to build and install. It also only costs about 25 dollars per latrine Engineers Without Borders USA. All Rights Reserved Page 10 of 29

11 Figure 4. (Top and Side View of Pour Flush Latrine, Isometric View of Operation) (Tilley, Elizabeth, Christoph Luthi, Antoine Morel, Chris Zurbrugg, and Roland Schertenleib. Compendium of Sanitation Systems and Technologies. Rep. EAWAG. Print.) Figure 5. (Overhead and Isometric View of Pour Flush Latrine with Twin Drainage Pits) (Tilley, Elizabeth, Christoph Luthi, Antoine Morel, Chris Zurbrugg, and Roland Schertenleib. Compendium of Sanitation Systems and Technologies. Rep. EAWAG. Print.) 2007 Engineers Without Borders USA. All Rights Reserved Page 11 of 29

12 4.5 Composting Urine-Diverting Latrine A Composting Urine-Diverting Dry Latrine is a pit-less latrine that employs natural decay of fecal matter into fertilizer. Urine and feces are kept separate in this design in order to decrease the time needed to compost and reduce harmful bacteria and odors. This design not only allows feces to be used as fertilizer, but allows urine to be converted to fertilizer as well. This design is built above ground and lined at the bottom making it easier to remove compost and avoid groundwater contamination. How quickly the composting box fills is dependent on size and frequency of use. However, because the urine is separated in this design, less mass is held in the composting box. The average time for composting is about a year, but this process can be quickened by implementing certain methods. If the box fills in less than a year the compost can be moved to another composting pile or stored elsewhere. Odor is greatly reduced by the diversion of the urine and the use of ventilation. Keeping the composting box dry and well ventilated reduces helps with this process. With this in mind, this design is most beneficial when constructing a latrine near houses or buildings. In addition, germs are killed more quickly in the dry compost and flies are much less of an issue. Cost of materials is higher for this design but the cost of labor is less because there is no need to dig a pit. With our current project, the materials that we need are easily obtained through village contacts (brick, stone, corrugated zinc). Most designs also recommend that an actual urine-diverting toilet bowl be used, but footpads will also work. The most important benefit to this design is that it doesn t have any effect on groundwater if it is properly built and used. As long as the box is properly lined, the urine collection system works properly and proper maintenance is performed, there will not be any adverse environmental effects. The major drawback of this latrine design is the maintenance it requires. Maintenance of this design is moderately high for both the user and the caretaker. The user must be sure not to mix urine and fecal matter. The urinal should be treated with a little bit of water after each use and the fecal matter should have two handfuls of mixed soil, ash or dry plant matter added after each use. The urine separator or urinal has to be checked occasionally to make sure it s not blocked. If the toilet odors bad the user must start adding more dry matter and the caretaker should check the ventilation tube. The fecal matter should be pushed down and stirred when the pile grows too high. Urine needs be removed and turned into fertilizer by mixing three parts water to one part urine. Most importantly, the fecal matter must be correctly aged and then used as fertilizer. If not it must be kept elsewhere if the box fills in less than the year suggested for the aging of fecal matter. This design can be constructed to have one or two chambers per seat. Although the two-chambered design takes more materials and takes up more ground space, it is the preferred version. There are also modifications that can be made to the design to make it more efficient. Building the latrine so the back faces the sun and painting the doors to the composting chambers black will help to heat up the feces which will speed up the composting process. Also, laying cornstalks, bamboo, branches or other dry plant matter on the foundation 2007 Engineers Without Borders USA. All Rights Reserved Page 12 of 29

13 of the pile helps to promote airflow; this will decrease odor even more so and speed up the composting process. Figure 6. (Side View of Composting Urine Diverting Latrine with Rear Access) (Tilley, Elizabeth, Christoph Luthi, Antoine Morel, Chris Zurbrugg, and Roland Schertenleib. Compendium of Sanitation Systems and Technologies. Rep. EAWAG. Print.) 2007 Engineers Without Borders USA. All Rights Reserved Page 13 of 29

14 5. ANALYSIS OF ALTERNATIVES Numerical Comparison This section uses a numerical scoring matrix which gives us a specific number value for the effectiveness that each latrine type has with each of the factors. The weighted scoring matrix shows us the importance of each factor compared to the other factors which signifies which factors are most crucial for a latrine project. The results of these two matrices are computed together to give us a final matrix which has numbers designating the top latrine choice. The following tables contain these matrices which give a final numerical answer that can be used for comparison. Table 1. (Numerical Scoring Matrix) Table 2. (Weight Factor Determination Matrix) 2007 Engineers Without Borders USA. All Rights Reserved Page 14 of 29

15 Table 3. (Final Weighted Matrix) 5.2 Alternative One: Pit Latrine Lifetime: 2/5. The lifetime of a Pit Latrine is not very long. Once the Pit Latrine becomes filled, it must either be pumped out, or covered up. The lifetime could be extended for the latrine if it was pumped, but that is neither sustainable nor cost effective, which will be discussed later. Also a Pit latrine should not be placed in an area prone to heavy rainwater (Baoma has a heavy rainy season) because it could flood and wash out the pit making it unusable. Sanitation/Cleanliness: 2/5. A pit latrine is more sanitary and cleaner than using the bush which is the current sanitation system. It would not, however, prevent odor, mosquitoes and bacteria from gathering around the pit. For these reasons the Pit latrine was ranked lowest amongst the latrine options. Cost: 5/5. The Pit latrine is definitely the easiest to build and construct. It would very few materials, all of which can be found locally, and labor to dig the hole the latrine has been considered. As noted later, a routine cost of pumping would be incurred if the locals wanted to use this latrine for many years. Maintenance: 5/5. This latrine is the easiest maintain out of all of the latrine options. It would only require occasional cleaning of the interior, depending on the habits of the locals. There is no other maintenance required. However, the major issue with this design is that if the community would like to use this latrine for an extended period of time it would need to undergo routine pumping which may not be feasible under the conditions. Effect on the Environment: 2.5/5. The Pit latrine poses some threats to the environment. If the pit is able to be lined (this has not been determined yet because we are waiting on local 2007 Engineers Without Borders USA. All Rights Reserved Page 15 of 29

16 materials available in Baoma) the Pit latrine would receive a 3, if not it would receive a 2. The reasoning behind this is, the lining could help prevent some waste permeability into the ground, but ultimately it is inevitable. It is definitely not the safest for the environment and there would need to extra caution taken when considering water sources and the water table. Social Acceptability: 3/5. The Pit Latrine received a three out of five when we looked at social acceptability for this design. It received this intermediate grade because of its simple use and design. One of the reasons that it did not get a better grade is due to the fact that it does not have ventilation in its design. These latrines can often have a constant odor to them making them somewhat unappealing. Overall Sustainability: The Pit latrine is the easiest to implement and definitely the cheapest to build/maintain, but these factors are not as important to us as others. Effect on the environment and sanitation are more important factors. The pit latrine would only last an amount of time depending on the size of the pit, and it definitely poses some serious threats to the environment and community. Extra caution would especially need to be considered since Baoma receives heavy rain during the rainy months. The site for the latrine will be right outside of the recommended 30 meters away from a water source, so this latrine is not favorable from the reasons previously mentioned. 5.3 Alternative Two: Ventilated-Improved Pit Latrine (VIP) Lifetime: 2/5. The lifetime of a VIP latrine is very similar to that of a regular pit latrine. The VIP latrine must either be covered up or pumped out once it becomes full. The duration of time the latrine can be used would again depend on the size and the willingness of the locals to pump it. Sanitation/Cleanliness: 3/5. The VIP latrine implements a ventilated pipe that extends from the top of the structure. This allows the odor and some bacteria to escape from this pipe. Netting attached to this pipe will also contain bugs and mosquitoes. This device makes a VIP latrine more hygienic than a regular pit latrine. Cost: 4/5. The VIP latrine requires few materials to be used during the building process. It would require a hole to be dug for the pit, the surrounding superstructure, and a ventilated pipe. Most of these materials can be found locally and are relatively inexpensive. It will be slightly more expensive than the pit latrine because skills and tools will need to be used to make the ventilated pipe. A routine pumping fee would also need to be incurred if the locals would like to use this latrine for an extended period of time. Maintenance: 5/5. Maintaining a VIP latrine is very simple. The pipe and netting surrounding the pipe would require simple routine cleaning, to remove any debris or bugs trapped within the pipe. It should also be cleaned periodically to prevent build up of bacteria and to make the latrine safer and more hygienic Engineers Without Borders USA. All Rights Reserved Page 16 of 29

17 Effect on the Environment: 2.5/5. Similar to the pit latrine, the VIP latrine has a high risk of groundwater contamination. The risk of the wastes permeating the ground is very high. These risks could be reduced if the pit is able to be properly lined, but it will still pose a threat. Extra caution would also need to be used since Baoma experiences a very heavy rainy season and the latrine will be placed fairly close to a water source. Social Acceptability: 5/5. The VIP Latrine received the highest scoring grade for social acceptability because it has a simple design that is very easy to use and also incorporates a ventilation system which greatly reduces odors. This makes it a widely accepted design by the community. Overall Sustainability: The VIP latrine is very similar to the pit latrine in many respects, not making it a preferred option. It is definitely easy to build and implement, and only slightly more expensive than a regular pit. It is however more hygienic and greatly reduces odor and mosquito attraction inside the actual latrine. The potential threat it poses to the environment and poor lifetime ratings are major concerns and factor that give this latrine and overall low raking compared to other latrines. 5.4 Alternative Three: Dual Pit VIP Latrine Lifetime: 4/5. Theoretically, this type of design can last forever. The alternating pit design means that when one pit is full, the other can be used as long as it has been emptied by the users. The lifetime of one of the single pits is generally accepted to be around a year, but this will vary with the number of users and frequency of uses. Sanitation/Cleanliness: 3/5. The double pit VIP latrine uses a design very similar to the single pit VIP latrine. The double pit VIP latrine uses a ventilated pipe that extends from the pit through the structure and out of the top. Each pit will have its own pipe. The design will vary depending on whether a single superstructure will be used for both pits or whether the superstructure will be moved from pit to pit. This allows the odor and some bacteria to escape from this pipe. Netting attached to this pipe will also contain bugs and mosquitoes. Cost: 3/5. Most of the materials used to dig the pits and construct the superstructure can likely be found locally and inexpensively. Building the two pipes will make this alternative more expensive than a single pit latrine. Similarly, if a larger superstructure that can accommodate both pits is chosen, more costs will be incurred, as well. Theoretically there will be no cost for pumping the latrine, as it should be placed above the water level and will not be wet when it needs to be dug out and cleared. Maintenance: 2.5/5. Maintenance is simple. The pipes will need to be cleaned semi-regularly to clear out the cobwebs and other various bugs and/or debris. The structures themselves will also need to be cleaned to prevent bacteria build up and make the latrine safer Engineers Without Borders USA. All Rights Reserved Page 17 of 29

18 Environmental effect: 4/5. The possibility of this alternative contaminating the surrounding groundwater is rather high. The pits can be lined to decrease the possibility, but it will always be there in some form. We must also take into special attention the fact that there is a heavy rain season in Sierra Leone, and this latrine is going to be placed near groundwater. This further increases the possibility of contamination of surrounding water. Social Acceptability: 5/5. The Dual Pit VIP Latrine received the highest scoring grade for social acceptability because it has a simple design that is very easy to use and also incorporates a ventilation system which greatly reduces odors. This makes it a widely accepted design by the community. Overall Sustainability: The twin pit VIP latrine is very similar to both the pit latrine and the single pit VIP latrine. It will be more expensive than both of those, due to the fact that two pipes will be constructed rather than one. A larger superstructure, if chosen, would also increase the overall cost of this alternative. Possible groundwater contamination is also a risk. The long lifetime, easy maintenance, and overall good hygiene are very good aspects to this latrine, though. 5.5 Alternative Four: Pour Flush Latrine Lifetime: 2/5. The lifetime of a pour flush latrine is similar to that of a VIP or pit. If one pit is filled the latrine would need to be pumped out or covered up like the other latrines. However, If two pits are used and each pit is large enough, the latrine s lifetime could be moderately increased. Sanitation/Cleanliness: 4/5. The pour flush latrine is a clean latrine alternative, the safest hygienically out of all of our options. The use of water to flush the wastes significantly reduces bacteria and odor. This eliminates virtually all mosquito and bug attraction. Cost: 3/5. A pour flush latrine would require more than a basic structure and pit. I pipe, two pits, and a diverting device would also need to be implement. These could increase more, depending on the availability of materials and skill of local workers. However, if Jeff Chaplin s design was implemented and changed to fit our specifications, the cost of the latrine could decrease dramatically. Maintenance: 3/5. Maintaining this latrine is fairly simple, but would involve daily work. A grey water system or a constant supply of refillable water would be needed in order for this system to be efficient. This could be very easy or hard depending on the creativity and commitment the locals would have for refilling the supply. Also routine cleaning would be required to keep it safe and sanitary. If a two pit system is implemented, once the wastes decomposes in one pit it will need to be manually removed. This hard and unfavorable work, but it would not need to be done very often Engineers Without Borders USA. All Rights Reserved Page 18 of 29

19 Effect on Environment: 3/5. This latrine will have a similar impact on the groundwater and surrounding areas as the VIP and pit. However, if two pits are used the possibility of water contamination is lessened. Extra caution is needed when building it and using it though because there still is a risk of wastes permeating into the ground. Social Acceptability: 3/5. The Pour-Flush design received an intermediate score for social acceptability. The Pour-Flush has a very sanitary function making it one of the cleanest alternatives being analyzed and reduces odors with proper maintenance but the design doe use extensive amounts of water which gets very scarce during certain times of the year Overall Sustainability: The pour flush latrine is a possible alternative and could be very beneficial to Baoma. However, there is one major drawback that will prevent this option from being successfully implemented: the need for a plentiful water supply for operation. Currently, such a water supply is not available near the school making this design option technically unfeasible for now. 5.6 Alternative Five: Composting Urine-Diverting Latrine Lifetime: 5/5. The composting latrine is a very efficient design and if used properly it can last for many years. The composting latrine allows all of the excreta and urine to be degraded and composted. This would give the latrine a longer lifetime if it is used properly and it would never have to be pumped. Sanitation/Cleanliness: 3/5. Since the urine and fecal matter are separated and the feces is contained in a dry composting box, this option has significant hygienic benefits. By keeping the feces dry, the decomposition process is expedited. This means that bacteria dies more quickly, flies are much less of a problem, and overall odor of the latrine is significantly less. Cost: 2/5.There is a significant amount of materials and design possibilities or options involved with this latrine, so the initial cost would be higher. There would not need to be a cost for labor or pumping; therefore the latrine would be a onetime only cost, which is great for the locals. Maintenance: 1/5. The composting latrine requires many things to occur to make it a successful and useful latrine. The wastes must be mixed with other dry matter to make it compost faster. The urine should also be added with some water to make it safer and degrade faster as well. Someone would need to be in charge of doing this on a very frequent basis. Also if the waste fills up faster than it composts, the wastes must be moved to another site for it to compost, and the latrine can continue to be used. Effect on the Environment: 5/5. If this latrine is properly built and is maintained correctly by the school, there are no negative environmental effects. The composting box is above ground 2007 Engineers Without Borders USA. All Rights Reserved Page 19 of 29

20 and lined, and the urine is collected in a leak-proof container which means no waste is able to permeate the ground and contaminate water supplies. Social Acceptability: 1/5. The composting urine diverting latrine received the lowest score for social acceptability. This has been determined by corespondance with our local NGO who has held multiple meetings with the community and school faculty. The issue of a composting dry latrine is that it requires a lot of maintenance and understanding to operate correctly. The composted waste will have to be moved out of the containing area in the latrine in order to continuously use the latrine. This job must be done by members of the community because they do not have surplus funding to pay for outside sources to routinely empty the latrine. It has been made clear that this is not a preferred job by the community members. Also the suggestion to use the composted waste as fertilizer is not very viable as 90% of the community members live by crushing stone at the local quarry. With this information we can conclude that we will not have adequate support from the community to maintain this type of design. Overall Sustainability: The composting dry latrine is the most sustainable of all of our possible latrine design options. If it is used correctly and built properly it could last for many, many years. It also can help the community to more efficiently grow crops in their small gardens by providing free fertilizer. The waste that turns into composts is safe to use a fertilizer after about a year of composting. This would not only be a environmentally safe and hygienic alternative, but it could positively impact the community s ability to grow crops and supply food for their families. The initial cost and maintenance is much more involved than other methods, but if the locals are willing to accept the idea of a composting latrine and commit to doing the maintenance involved, this design will be incredibly beneficial to not only the school, but also the entire community Engineers Without Borders USA. All Rights Reserved Page 20 of 29

21 5.7 Logical Comparison The factors from the scoring matrix include lifetime, cleanliness, cost of materials, effect on environment, maintenance, and social acceptance. Lifetime of the latrine depends on the capacity that the latrine can hold and the durability of the materials and structure. This factor illustrates the latrine s ability to withstand natural weather phenomena and the test of time, for example, the project site in Sierra Leone is prone to heavy rains and flooding so the structure must be strong enough to withstand these phenomena. Permeability and strength of the material are also important factors to consider. During the assessment trip these factors were taken into account when collecting aggregate samples. Long term maintenance should also be considered. If this is to be a sustainable project, burying the pit would not be an option. If the old pit was buried when it has filled up, a new pit would have to be dug and the superstructure would need to be moved. In order to have a permanent location, the latrine would need to be emptied regularly or incorporate a composting system. This could be accomplished by either pumping the pit or manually removing the waste. When considering the single pit option, the pit design, the VIP design, and the pour flush design would all require pumping to remove the waste sludge. The dual pit option for the pour flush design does allow for one pit to decay while the other is in use. Nevertheless, it would still be difficult to empty due to the depth of the pit. The composting urine diversion design would allow much easier access and would cause the waste to harden, making it more manageable. Sanitation/Cleanliness will look at the factors of odor and hygiene. The pit design has the smallest degree of cleanliness with the waste merely resting beneath the opening. The VIP system implements a ventilation duct that works by directing air flow into the pit and out through a small opening above the superstructure. This greatly reduces the odor. The pour flush latrine is the best choice in terms of hygiene and odor because the flushing mechanism uses water to seal off the waste matter. The dual pit VIP would be the same as the VIP because it only differs by the number of pits. The composting urine diversion system would be better than a simple pit but not as effective as a pour flush latrine. The above ground nature of this design means that it is more likely to odor. However, the diversion of urine and any liquids will help to negate this effect and the composting process will allow pathogens to be destroyed in a shorter amount of time. Cost of the materials was not a huge factor in the scoring of the latrine design. The cost of the initial construction of the latrine will be taken on by EWB. Some of the latrine systems are still easier and cheaper to construct than others. The pit would only require basic materials for the superstructure and the work necessary to dig the pit. Compared to the pit latrine, the VIP latrine needs the same materials as well as ventilation tube extending from inside the pit to a height of 50cm above the structure. The pour flush mechanism is more complex than the first two alternatives and results in a higher cost for the system, in addition to the superstructure 2007 Engineers Without Borders USA. All Rights Reserved Page 21 of 29

22 and pit. The pour flush design requires a small degree of piping, a system that would allow the human waste to enter the pit when water is poured into it. The dual pit VIP would be slightly higher than the VIP for cost and material use because it has an extra pit for each stall. Finally, the composting urine diversion latrine would be the most costly. However, a pit is not part of this design and labor will not be required to dig the pit, saving time and money. In terms of actual materials, this design does require the construction of a composting bin along with the superstructure. The bin can be created using local materials. This latrine system must be lined so the waste does not leak out. Also, many potential designs suggest using an urine-diverting toilet bowl in order to facilitate daily use. This would add to the composting design cost but a foot pad system can also be used. The latrine s effect on the environment is one of the most important factors, evident from the weight scoring factors. The latrine s proximity to the water table and the surrounding permeability of the soil will control whether or not the latrine can be safely implemented without any harmful effect on the village. The pit and VIP latrines both have relatively dry pits and thus if an open bottom pit design is used. This open bottom design will have to be below surface water levels and above ground water levels in order for it to be successful. This will have a small effect on the surrounding waterways. They still pose a risk due to the permeability of the ground. However, the pour flush latrine has a greater effect on the water table. The water necessary in its daily use will allow the harmful bacteria to spread farther through the soil than one of the dry pits. Because the location of the latrine will be close to a stream, this will be a major setback of the pour flush design. The dual pit VIP will be in junction with the pit and VIP designs if an open bottom pit design is used. The composting urine diversion design will have a much smaller effect on the environment due to its lined box located above ground. Also, the compost can later be used as fertilizer for crops. As for any of the latrine systems, the effect on the environment, i.e. ground and surface water, would be reduced if lining was added. Latrine maintenance is a large factor in the scoring matrix. This represents the time and upkeep necessary to keep the latrine system clean and usable. The pit latrine requires virtually no maintenance other than basic cleaning. The VIP and dual pit VIP latrines have similar maintenance requirements to that of the simple pit latrine except that the ventilation tubes must be checked regularly; this makes sure the pipes are free from debris and bugs, which could block the airflow of the pipes. The pour flush latrine has the same simple cleanliness requirements as well as having the pan-pipe system to clean. With the pour flush latrine, a double pit can be constructed. If the pits were to be emptied every few years, this method would excel. The double pit mechanism would allow for one of the pits to be in use while the other composts, allowing it to be manually removed without the need for pumping equipment. The composting urine diversion design has some major maintenance requirements. Although, it doesn t need to be pumped, it does need to be operated and maintained on a daily basis. For instance, the urine and solid waste must not be mixed together, the urine needs to be diluted with water and soil needs to be added to the fecal matter after each use in order to promote composting. Failure to do so could result in the compost not maturing in a timely fashion Engineers Without Borders USA. All Rights Reserved Page 22 of 29

23 One of the most important factors that needs to be taken into account when assessing and implementing a project is the component of social acceptability. In manufacturing a sustainable, safe and effective project the community must first be asked what they are willing to do, how the project might adversely effect, and more importantly affect, their community and whether the community feels comfortable with the project and its components. If these needs are not met, the project will eventually go into disrepair and become obsolete. As such, social acceptability and project sustainability go hand in hand, if the project is not accepted within the community, the project will not last long. We discovered through correspondence with the community that the Composting Urine-diverting latrine would not be a feasible design. The reason for this being the high maintenance and education factors resulting in the inability of the community to properly care for the design. The education factor is very important to take into consideration because the intended benefactors are of young age. The Composting Urine-Diversion system is rather complicated and it is unrealistic for us to expect young children to use it correctly. On the other hand, the VIP and Dual Pit VIP latrines are relatively simple and require minimal education and maintenance for proper operation. The other factors not included in our matrix are complexity and constructability and project sustainability. Constructability and complexity will be one of the considerations in the initial building and daily use of the latrine. The superstructure of the latrines will all be relatively similar. This will be created using local materials and building styles. The structure will be designed as to utilize easily found local materials. Another consideration would be whether or not the system is simple enough to be used by the villagers, and if it is complex to use, how will the team educate the locals. The easier it is to use, the quicker it will likely be accepted. In terms of use, the pit, VIP, and dual pit VIP are all very simple. The pour-flush has the requirement of flushing water after every use. The composting urine diversion latrine is the most complex if a urine diverting bowl is not used a urinal system will be required. Probably the most essential factor in determining the perfect latrine system is project sustainability. Will the residents be able to use and maintain the project after the building committee has left? Does the project require outside help to maintain? Is the project simple enough to replicate if more are desired? These questions include many of the factors already listed here such as lifetime, complexity, or maintenance. The pit and VIP latrines are both easy to construct but are not sustainable in the long term because they will need to be filled in and pumping is not a financially viable option. The pour flush latrine can be a permanent structure if the double pit system is implemented along with the use of composting techniques. The Dual Pit VIP Latrine has potential to solve many of these problems. It is designed very similar to the VIP but has second pit for each stall. This second pit, if designed properly can be switched to primary use when the other is at max capacity. This feature allows one of the pits to be in use at all times while the other can be emptied if needed in the future. Access hatches can be installed 2007 Engineers Without Borders USA. All Rights Reserved Page 23 of 29

24 to open up the pits when the time comes to empty. This allows the dual pit VIP to be both used as a pit latrine with a composting option. The Composting Urine Diversion design is built to be permanent but the system is fairly complex. This will only work if the village is educated on the use and maintenance of the composting bin. This should be considered for the other possible designs as well. Overall, project sustainability is a factor that takes many different ideas into account and it can be difficult to select a perfect design. However the composting urine diversion latrine stands out in the sustainability factor. 7. DESCRIPTION OF PREFERRED ALTERNATIVE After analyzing the results from the comparisons, it was clear that the majority of our team favored the Composting Urine-Diversion design. We found that this design if maintained properly can be the most sustainable design within the community and would also have the lowest impact on the environment. However there is one factor that makes this design unfeasible: social acceptability. Because of this critical factor, we turned to the VIP Latrine and Dual Pit VIP design. Theses designs scored first and second respectively in the overall weighted scoring matrix making them our top choices after logical comparison. One of the main reasons why the Composting Urine Diversion Latrine was so favored was due to the fact that it could be the most sustainable design with a very long lifetime if maintained properly. Our team wants to design a project that has the potential to be beneficial for the community for a very long time. The Dual Pit VIP design combines both the potential for a long lifetime and be sustainable with the simplicity of design and acceptance in the community. It has low maintenance and is easy to use for the children. For a successful and sustainable project, we must have the community s support and willingness to sustain the project on their own. Therefore, the Dual Pit Ventilated Improved Pit latrine is the best choice for the schoolchildren and community in Baoma Engineers Without Borders USA. All Rights Reserved Page 24 of 29

25 8. MENTOR ASSESSMENT PSU EWB 523 Analysis Mentor Assessment The majority of the homes viewed during the assessment trip in July 2010, and the health interviews conducted by the travel team with community families indicate that sanitation education and practices, especially for human waste are lacking in the community. We witnessed human waste near the stream banks of the village and along walking paths. Most open water sources were contaminated and I personally saw human waste near the main spring source. In addition, residential structures were built very near the main spring water source. While we talked with community members who do practice sanitation and one family interviewed for the health assessment had built a latrine, the majority of community members used the "bush" for their toilet. The PSU EWB chapter is dedicated to implementing a sustainable design. While this would warrant the construction of a composting type toilet that would have the longest potential service life, the response from the community is that use of composted waste as fertilizer, and the emptying of the composting toilet (or pit latrine) does not appear to be socially acceptable and therefore not a viable option. Although this could be overcome by a long-term educational and maintenance program during the 5 year commitment by PSU EWB, at this point there is little assurance that the community and school would properly maintain a composting latrine. Another factor in the analysis is the opportunity for the school to be relocated on land donated by the village chief. If this were to occur within the next several years, the PSU EWB chapter could assess building a latrine with a longer service life. Another key decision in the analysis is to preclude a pour-flush latrine. Although the benefits of reduced odor and cleanliness are favorable, the lack of a viable water source during the dry-season could potentially lead to a pour-flush latrine becoming unusable for feces. Given these factors and the buy-in from the community, I concur with the alternatives analysis that a two-person, dual pit ventilated-improved pit latrine is the preferred alternative. Looking ahead to the design phase, the major factors to be considered and incorporated into the design will be the proximity of the school master's residence and school buildings, the intermittent stream along the east boundary of the property, property sizing for the children (primary school age), a sanitary platform that is easy to maintain, and a superstructure that will be sturdy for frequent use, but can also be decommissioned after the pit is full or if the school is relocated. Mentor Name Richard Kercher 2007 Engineers Without Borders USA. All Rights Reserved Page 25 of 29

26 Appendix Figure 7. (Map of the Village of Baoma) 2007 Engineers Without Borders USA. All Rights Reserved Page 26 of 29

27 Figure 8. (This is an overhead view of our proposed project site) 2007 Engineers Without Borders USA. All Rights Reserved Page 27 of 29