Santiago Creek Dam Borrow Area Geotechnical Investigation
Summary
SCH Number
2024081117
Public Agency
Irvine Ranch Water District
Document Title
Santiago Creek Dam Borrow Area Geotechnical Investigation
Document Type
NOE - Notice of Exemption
Received
Posted
8/27/2024
Document Description
Irvine Ranch Water District (IRWD) own and operate the Santiago Creek Dam, which impounds Irvine Lake. Santiago Creek Dam is a 136-foot-high rolled earth embankment located on Santiago Creek in Orange County, CA. Santiago Creek Dam forms Irvine Lake, which provides water supply to surrounding communities for both agricultural and municipal use. The outlet works and reinforced concrete spillway at Santiago Creek Dam were constructed in 1932. The dam and the reservoir are under the regulatory jurisdiction of the California Department of Water Resources, Division of Safety of Dams (DSOD). IRWD is implementing a long-tem1 plan to replace the dam spillway and the outlet tower. Geotechnical investigations of the site are needed to inform the upcoming design phase for those facilities.
IRWD proposes to conduct approximately 12 geotechnical exploratory test pits and approximately 14 vibratory borings over and around Irvine Lake. Each geotechnical test pit would be approximately 10 feet deep and would be 3 feet in diameter and the work area would be approximately 20 feet by 20 feet. At the test pit locations, contractors will utilize a small rubber-tracked mounted excavator with an excavation bucket for digging and tracking over brush. These locations may be modified by IRWD as needed in the field to avoid trees, sensitive vegetation, or jurisdictional areas, if needed. Samples of subsurface materials would be collected from the test pits for examination and laboratory testing. Following the completion of the test pit, each hole would be backfilled using the dirt spoils that came from the hole. Where required,
permits will be acquired for the Geotechnical Investigation work for Regional Water Quality Control Board, California Department offish and Wildlife, US Fish and Wildlife Service and Army Corps of Engineers.
Contact Information
Name
Andy Uk
Agency Name
Irvine Ranch Water District
Job Title
Environmental Compliance Analyst
Contact Types
Lead/Public Agency / Project Applicant / Parties Undertaking Project
Phone
Email
Location
Coordinates
Counties
Orange
Regions
Countywide, Southern California
Cross Streets
N/A
Zip
92676
State Highways
SR-241, SR-261
Waterways
Irvine Lake, Santiago Creek
Notice of Exemption
Exempt Status
Categorical Exemption
Type, Section or Code
Section 15306, Class 6 (lnformation Collection)
Reasons for Exemption
The effects of the proposed project are Categorically Exempt from the
requirements to prepare additional environmental documentation per California Environmental Quality Act (CEQA)Guidelines, Section 15306, Class 6 (lnformation Collection). The Class 6 Exemption consists of basic data collection, research, experimental management, and resource evaluation activities which do not result in a serious or major disturbance to an environmental resource. These may be strictly for information gathering purposes, or as part of a study leading to an action which a public agency has not yet approved, adopted, or funded. The proposed project consists of exploratory test pits which would require some degree of ground clearing and vibratory borings that would occur on the lake over water.
This geotechnical investigation is important as it would inform a larger project's borrow site location and is strictly for information gathering purposes. This work would lead to an action taken by IR WD that has not been approved, adopted or funded. Additionally, IRWD would obtain any additional permits needed from the Regional Water Quality Board, US Fish and Wildlife Service, California Department of Fish and Wildlife and Army Corps of Engineers. Therefore, the proposed project would meet the criteria of the Class 6 exemption in that it consists of basic data collection and research and would not result in a serious or major disturbance to an environmental resource. In addition, pursuant to Section 15300.2 (c) and
15306 of Title 14 of the California Code of Regulations, there are no unusual circumstances in respect to the proposed project for which staff would anticipate a significant effect on the environment.
County Clerk
Orange
Attachments
Notice of Exemption
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