VIP Latrine Design Analysis

  To gain understanding and practice in dealing with sanitation issues in developing regions a design analysis of an Ventilated Improved Pit Latrine. The design analyzed can be found here Design Plans.

  In order to determine if the original design is large enough, the number of people served for various design lives were calculated. Only the rectangular area under the user-interface hole (not the side square with the access door) was included in the pit volume calculations because solids would not fill the area under the access door. Also, a 0.5 m dead space was assumed between the top of the solids and the superstructure. This results in the dimensions of the original being 0.7 m x 1.6 m x 1.1 m and a volume of 1.2 m. A solids accumulation rate for a dry pit of 0.06 m³/person/yr was assumed.

  If the family served was assumed to be 4 people, the design life of 5 years is sufficient. These calculations show the original pit volume is sufficient for a family of 4; however, the shape of the pit is a problem. In order to clean the pit, someone must climb into a 0.8 m x 0.8 m x 1.6 m area and then reach around a corner in order to reach the area where solids accumulate. This would be a cramped and dirty task for any adult. In order to improve the pit, the shape of the pit is changed into a rectangle, where the access door would be above the area where solids accumulate so they can be shoveled or mechanically removed from outside of the pit. The proposed design is 0.8 m wide x 2.8 m long x 1.6 m deep. This depth includes dead space. This volume, 2.5 m³ is still sufficient for the family of 4 for five years, but now is easier to remove the solids. See Appendix 1 for plans of the revised pit layout and superstructure.

 The second revisions are to the materials of construction. While steel corrugated roof is an acceptable material, it may not be easily repaired or replaced by locals in rural South America. It also is more expensive than local materials. It is suggested the roof be changed to a thatch roof made with local materials to make it easier for locals to maintain and replace if necessary.

  It is also suggested the vent pipe material be changed for similar reasons. PVC pipe can become brittle when exposed to high sunlight but stabilized PVC can be expensive and difficult to come by. In order to make the vent easy to maintain and replace it is suggested to be a cement-rendered reed pipe.

  The current design appears to require the use of a door for privacy and the adobe walls and steel roof do not provide for much ventilation. In order to fix both problems, the shape of the superstructure has been revised. A square spiral structure has been designed for the revised superstructure. See figures in Appendix 1 for superstructure plan.

Improved Design Plans

Superstructure Profile

Superstructure Front

Superstructure Plan

Slab Plan

Pit Plan

A Look at the Water and Sanitation Situation in Vietnam

 Vietnam, officially the Socialist Republic of Vietnam, is a developing county located on the Indochina Peninsula. The 13th most populated country in the world; it has made substantial strides toward Millennium Development Goal, or MDG, target 7c. A summary of statistical data on Vietnam can be seen in table 1.

 MDG target  7c aims at ensuring environmental sustainability, specifically halving the proportion of the population without improved drinking water and basic sanitation by 2015. Improved drinking water is defined by the type of technology and level of service more likely to provide safe drinking water. Sources include in domestic connections, public standpipes, protected wells and springs, and rainwater collection. Unimproved sources would include unprotected wells and springs as well as vendor and tanker truck provided water. To ensure sustainability the withdrawal should not exceed what is available which includes sound supply and management practices.

 Currently access to improved water sources and sanitation in Vietnam is fairly good and the MDG has already been reached. Currently 94% of the population has access to improved water sources and 75% has access to basic sanitation. Compared to 58% and 35% respectively in 1990, both sectors currently comply with the MDG. The largest improvements have been in in rural areas though this may be due to both urban migration and the large margin for improvement. This is not to overshadow urban progress as it has been substantial as well. These figures as well as others can be seen in table 2. The progress of improvement from 1990 to 2008 can also be seen in the drinking water ladder, figure 1.

Vietnam
Location	Southeast Asia
Bordering Nations	China, Laos, and Cambodia
Area	310,070 sq mi
Population
Population	90.55 million
Population Growth Rate	1.077
Urban Population	30.00%
Infant Mortality Rate	20.9 deaths / 1000 live births
Life Expectancy	72.2 yrs
Total Fertility Rate	1.91 children per woman
Literacy Rate	94.00%
Economy
GDP (PPP)	$276.6 billion
GDP Ranking	42
GDP by Sector
Agriculture	20.6%
Industry	41.1%
Services	38.3%
Labor Force by Sector
Agriculture	53.9%
Industry	20.3%
Services	25.8%
Unemployment Rate	4.4%
Population Below Poverty Line	10.60%
Table 1. Country Profile
Water and Sanitation
Renewable Water Resources	891.2 cu km
Freshwater Withdrawl	71.39 cu km
Freshwater Withdrawl per Capita	847 cu m
Freshwater Usage
Domestic	8.0%
Industry	24.0%
Agricultre	68.0%
Improved Drinking Water 2008
Urban	99.0%
Rural	92.0%
Total	94.0%
Improved Drinking Water 1990
Urban	88.00%
Rural	51.00%
Total	58.00%
Improved Sanitation 2008
Urban	94.0%
Rural	67.0%
Total	75.0%
Improved Sanitation 1990
Urban	61.0%
Rural	29.0%
Total	35.0%
Table 2. Water and Sanitation Data



Figure 1. Vietnam Water & Sanitation Ladder

Statement of Purpose

 Hello to all you water lovers. My name is Jacob Mueller and over the past year I have become intensely interested in water and sanitation in the developing world and the decentralized solutions to these problems. The more information I uncover, the more I feel that these types of solutions are essential to improved water availability, water quality and overall health worldwide. I am currently studying environmental engineering at N.C. State University and have begun to focus on the subject. I recently completed my senior design project on latrine design and  am presently enrolled in a class about the issue specifically.

 In order to further my knowledge of the subject, as well as develop a view of the most current trends in the area, I have created this blog as an outlet of information and record of what I discover. I will include book reviews, information from industry and business leaders, case studies on related projects, and anything else I can unearth. Through this I hope to create a comprehensive view of the overall water situation with a special focus on non-traditional and developing world approaches. When all is said and done I, as well as anybody else who follows, should be fully knowledgeable and competent on the subject.

 So read, learn and enjoy. I look forward to meeting all who share my intrest in tackling these problems and working to make the world a better place. Talk to you soon.

- Jake