MS in Civil Engineering (M.S.C.E.)
Degree Granting Department
Civil and Environmental Engineering
James R. Mihelcic, Ph.D.
Maya Trotz, Ph.D.
Jaime Corvin, Ph.D.
degradation, latrine, pit contents, sanitation, Sub-Saharan Africa, West Africa
Access to appropriate sanitation facilities as well as access to clean drinking water are considered fundamental human rights (Carr, 2001; Bjorklund & Sjodin, 2010), yet roughly 2.5 billion people on the planet lack access to an improved form of sanitation (WHO/UNICEF, 2014). Additionally, many entities responsible for emergency excreta management and sanitation management design guidelines, specifically solids accumulation rates in latrine pits, use rates that are 30-60 years old and may be established from dated knowledge on diet and lifestyle trends (Franceys et al., 1992; Harvey et al., 2002; Harvey, 2007). Using solids accumulation rates that are dated as well as non-local can lead to under design of latrine pits (latrine pits fill faster than expected and designed) or over design of latrine pits (resources and materials are over used in construction and design).
Previous research showed that solids accumulation rates in pit latrines ranged from 18 L/person/year to 70 L/person/year though no accumulation rates have been reported for schools. The reported differences in solids accumulation rates were found to depend largely on local user rates and behaviors, the amount of material added to the latrine (both organic and inorganic matter), and the porosity of the soil surrounding the pit. Wood (2013) suggested that solid waste could compose 10-40% of waste accumulated in a pit. Furthermore, fecal generation rates of individuals were also found to differ by country, region and individual (Franceys et al., 1992).
An assessment of several methods for measuring accumulation rates was also performed. It was determined that the laser distance meter technique, as well as the use of a graduated metal rod were the best two ways to determine slab to pit content depths in rural communities. Compared to other methods, such as the stereographic imaging technique, and the automated laser scanner technique, the laser distance meter technique and the use of a graduated rod require less expertise and do not require camera and computer resources.
This study also developed a method to assess solids accumulation rates of latrines at three rural schools in Saclepea City, Nimba County, Liberia. Depth measurements were taken from the latrine slab to the surface of the pit contents from early May 2014 until mid-June 2014. The accumulation rates were found to be extremely similar for each latrine for all measurements taken, with differences in depth of only 1-3 cm observed over the six-week measurement period.
Little research was identified on the effects of feminine waste on solids accumulation rates in latrines and no literature was found concerning the effects of feminine excretions on the degradation of pit contents. More research is thus needed to assess the possible effects the addition of menstrual blood and menstrual excretions can have on degradation rates as well as the lifespan of viruses and other infectious agents in pit contents and the surrounding soil. This is particularly important with the presence of contaminated wastes from victims of Ebola Virus Disease being disposed of in latrines and other sanitation infrastructure in rural areas of West Africa.
Scholar Commons Citation
Murphy, Caraline M., "Solids Accumulation Rates of Latrines at Rural Schools in Nimba County, Liberia" (2015). USF Tampa Graduate Theses and Dissertations.