CHAPTER 3 - METHODOLOGY

The project team adopted a workshop approach with City engineering staff to determine the design criteria, study areas, analysis processes, deficiencies, alternatives, and solutions. This section describes the methodology followed in developing the Master Plan.

HYDROLOGY

Hydrology is the study of the movement, distribution, and accumulation and management of water. For this Master Plan, the hydrology performed includes selecting a rainfall design frequency and storm distribution, subbasin area delineations and calculations, calculating runoff potential using soil data, land cover, and impervious surface estimates, and estimating the timing of peak runoff. The first portion of this chapter details these methods in greater detail.

Design Frequencies

The City selected design storm frequencies of 10-year (10% chance of being equaled or exceeded in any given year) and 100-year (1% chance of being equaled or exceeded in any given year) for this study. Criteria included:

∙   10-year design capacity for the initial drainage system. The initial drainage system includes storm drains, gutters, and roadside ditches.

∙   100-year capacity where flooding of homes may occur.

∙   100-year capacity on all detention/retention limited to storm drain hydraulic capacities.

∙   100-year capacity with a freeboard of 2 feet for natural drainages as defined in Chapter 2.