New Antenna at the Sonoma Mountain Communications Tower Site Project


SCH Number
Public Agency
Sonoma County
Document Title
New Antenna at the Sonoma Mountain Communications Tower Site Project
Document Type
NOE - Notice of Exemption
Document Description
PROJECT DESCRIPTION: The County of Sonoma proposes to lease space at its existing Sonoma Mtn. Road telecommunications facility to The United States Geological Survey (USGS) for construction of a new 40 ft. tall tower, migration of certain antennas and continued operations from the County vault. The main County telecom facility is located at 2482 Sonoma Mountain Rd., Petaluma, CA (APN 136-190-016) where Sonoma County owns land and operates its 40 ft. microwave tower, 185’ main self-supporting tower and vault, and accommodates numerous other public agencies in connection with their respective public safety and emergency communications missions inside fenced enclosures (the “Sonoma Mtn. Site”). The County’s telecommunications system, which includes a network of communications towers and equipment, supports first responder agencies, public safety fire cameras, and other important Countywide radio services. This system is managed by the County’s Sheriff’s Office Telecommunications Bureau (T-Comm). USGS has requested and the County expects to enter into a site agreement for USGS’ construction and installation of new equipment including a new 40’ tall tower, new concrete pad and for the County to continue to host USGS antennas on the County owned Microwave Tower. USGS’s use of the premises shall be for transmitting seismic data for rapid earthquake detection and as a reception point for seismic monitoring sensors. USGS proposes to remove an abandoned tower and existing tower pad at the site, build a new 64 sq. ft. concrete pad, and construct a new self-supporting forty (40) ft. tower substantially within the same footprint of the existing pad to be removed. Upon completion of construction, USGS will move and consolidate its radios in the County’s vault and USGS will migrate several antennas from the County’s Microwave Tower to the USGS Tower. USGS will also continue to operate two (2) of its 4 ft. dish antennas from the County’s Microwave tower. The radio equipment serving the new tower when built will remain located in the existing vault. EXISTING FACILITIES ON THE SITE: Existing facilities on site consist of additional towers and separate buildings housing telecommunications equipment for purpose of providing communications services to the local and other county/government agencies including : (a) Marin Emergency Radio 632.5 square foot ground space, which supports a 10’ x 20’ vault and propane generator with 499 gallon tank with antennas on the County main guyed tower and MW structure; (b) State of California has licensed 50’ x 50’ ground space, which supports a 12’ x 30’ vault, 35’ tall self-support tower and propane generator with a 499 gallon tank. The State also has radios in the County vault, antennas on the County main guyed tower and MW structure, and a GPS antenna mounted on the fence; and (c) Golden Gate Bridge & Hwy Transportation District has licensed 12’ x 12’ ground space, which supports an 80’ tall self-support tower with radios in the County vault, antennas on the County MW structure and two GPS antennas mounted on the fence. ADJACENT EXISTING FACILITIES: At the Site there are several adjacent existing facilities specifically: (1) PG&E has a facility adjacent to the County Facility under a lease from Sonoma County through Regional parks for approximately 1,250 square feet of ground space, which consists of a 300 square foot vault and a forty-five foot (45’) tall tower; and (2) Crown Castle develops and operates a worldwide network of communications infrastructure and Crown Castle facility is directly adjacent to the County Facility. Crown Castle leases 3,375 square feet of ground space from Sonoma County through Regional Parks for this facility. The facility consists of a 199’ tall self-support tower, a 10’ x 20’ vault and an 8’ x 10’ abandoned building. The 10’ x 20’ vault contains AT&T Mobility radio equipment. There are approximately seventeen (17) panel antennas, related equipment and seven (7) MW dishes mounted on the Crown Castle tower associated with the AT&T Mobility cellular phone installation

Contact Information

Robert Aguero
Agency Name
Permit Sonoma
Job Title
Senior Environmental Specialist
Contact Types
Lead/Public Agency


Rohnert Park
Northern California
Parcel #

Notice of Exemption

Exempt Status
Categorical Exemption
Type, Section or Code
Section 15303
Reasons for Exemption
The proposed project is categorically exempt under Section 15303 of the State CEQA Guidelines. The project consists of the construction of new, small structures. In addition, the project is also categorically exempt under Section 15301(b) of the State CEQA Guidelines. It is the minor alteration of an existing public facility involving negligible expansion of use.
County Clerk


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