Hydrological Analysis of Potential Campus Expansions by Two Methods

University A has proposed an increase of student housing by constructing additions to three existing buildings and building a new student dormitory. This student summer research project was designed to analyze the hydrological impact of new construction activities on campus by using two published models for runoff analysis - the rational method and the National Resources Conservation Service (NRCS) method. This project was divided into two parts. The first involved surveying the proposed construction areas, collecting rainfall data, applying the rational and NRCS methods, and calculating the runoff before and after the proposed construction. In addition to the surveying and calculations, existing stormwater management systems on campus were also studied. These revealed that the firm contracted to build the new student dormitory had designed for and installed a system to accommodate the additional runoff. The research focus therefore shifted toward the additions to existing student housing units on campus and how they would affect the stormwater runoff. From field observations, it was determined that the drainage systems for this area were at an estimated 40 percent capacity for a five year storm that lasted two hours. If any sizeable additions were to be added to the three buildings, the design capacity of the existing culverts, storage ditches, and other retention areas would be exceeded. This would cause flooding of the practice athletic fields, two parking areas, and a fire road. If this occurred in winter it could cause excessive ice across the driving surfaces. The existing power plant in this area is also expected to be upgraded in the near future, increasing its impervious footprint and adding runoff to the area. The construction firm that was consulted for this project recommended that the stormwater control units to address runoff from the power plant expansion also account for the excess runoff from any additions to the three existing student housing units. This will include redesigning the culverts and shallow paved channels that manage the surface runoff so as to increase capacity. The second part of the project involved creating a simple application in Microsoft Excel to use both the rational method and the NRCS method to determine the rainfall runoff of a given property. The application was designed as a tool to aid in college classroom learning and application of the two methods to analyze stormwater runoff.