Stanislaus Stormwater Drainage

Project Description

The stretch of State Route (SR) 99 between post mile 15.0 and 16.3 Situated in Modesto, features a drainage system composed of an interceptor ditch. This ditch runs parallel to the northbound side of SR 99, adjacent to 6th Street, and the southbound side, adjacent to 5th Street. Its purpose is to gather all stormwater and redirect the sheet flow down the cut slope of the highway. The interceptor ditch carries storm water to down drains into State highway drain features. Highway drainage that traverses along ac dikes carries SR 99 storm water into drop inlets crossing the highway into a main storm drain located in the median. All storm water is captured and then pumped to a pump house, filter and into the Tuolumne River.

The inceptor ditches are unlined and built in 1965. Due to the age of the unlined ditches and rodents burring into the ditch banks causing the slope to erode (and at times potentially fail) carrying debris that resides on the mainline SR-99 shoulder drainage system. An emergency repair was made in 2005 of a slope failure and another incident, drain inlet plugged and field maintenance put in a temporary drain line made of pvc to redirect excess storm water and alleviate the overburden drain inlet on the mainline. This spring of 2023 there was another emergency project on the northbound side that dealt with stormwater that collected, and it washed the slope down onto the number three lane due to a culvert that was burnt.

Project Benefits

Purpose

The purpose of this project is to improve the antiquated drainage features and systems, provide MVPs, vehicle access and personnel gates along SR 99 improving worker safety.

Need

The project is needed because existing drainage features are antiquated and inadequate, and current access points for vehicles and personnel are limited, creating safety hazards for workers along SR 99.