Theses and Dissertations

Date of Award


Document Type


Degree Name

Master of Science (MS)


Civil Engineering

First Advisor

Dr. Andrew Ernest

Second Advisor

Dr. Ahmed Mahmoud

Third Advisor

Dr. Jong-Min Kim


The objective of this research project is to develop two evaluation models, one using excel to provide a design criterion for wastewater pumping stations in collecting design parameters and information effecting efficiency and performance of the pumps. Secondly, to develop a linear regression model for these parameters giving a correlation between dependent and independent variables to verify adverse environmental aspects. This study is based in the City of Weslaco, pertaining to the north waste watershed. The parameters collected are age, efficiency, service area, total dynamic head, existing conditions, monthly sanitary sewer over flow work orders, precipitation data, population by service area, and amount of residential and commercial lots per service area. Overall, fifteen (15) wastewater pumping stations were evaluated. The north waste watershed for the City is comprised of fifteen (15) lift stations, countless linear feet of force and gravity main sanitary sewer lines. Problematic issues involving failure of the lift stations involve the pumps, deterioration of the wet well due to age, and increase in capacity due to new development.

Age of the lift station of course, correlates with efficiency of the existing pumping station. The efficiency was read from each pump curve provided by the manufacturer of the pumps and evaluated against the age of the lift station. As age increases, efficiency decreases. This test was run to affirm accuracy of the linear regression models to follow.

Adverse environmental problematic issues include consistent sanitary sewer over flows, backed up gravity mains due to heavy rainfall events, which cause odor and the raw sewage within those pipes or lift stations to become septic due to the amount of time spent stagnant. This causes health hazards, soil infiltration which can contaminate our aquifers, and pressurized sewer lines to burst or rupture.

The environmental impact precipitation has is hypothesized to directly correlate with the amount of SSOs per month. A total of 147 SSOs in 2019 for the City of Weslaco, and 538 in 2018. Precipitation data was gathered, and a linear regression model was drawn. Results showed as precipitation data increased, as did the amount of SSOs at a significance of 40%.

Capacity was then tested against residential growth in the city. The city adopted a 2040 Land Use/Zoning Map in 2018 providing all undeveloped land a zone. Using this, predictions for residential subdivisions were drawn and broken down into number of lots per subdivision per service area. Capacity in the area was then gathered and hypothesized to increase as the amount of residential subdivisions increases. The linear regression model shows the correlation to be at a significance of 53%.


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