MGDP Concentrate Conditioning Project


SCH Number
Public Agency
Zone 7 Water Agency
Document Title
MGDP Concentrate Conditioning Project
Document Type
NOE - Notice of Exemption
Document Description
The Mocho Groundwater Demineralization Plant (MGDP) began operating in 2009 to manage the buildup of salts and minerals within the Livermore-Amador Valley’s groundwater basin using reverse osmosis (RO) of groundwater to produce demineralized water. Concentrated brine is a byproduct of this process. Over time, the process creates mineral scale on pumps and piping, decreasing the inner diameter of the brine disposal pipeline and reducing the plant capacity. Left unaddressed, the flow capacity would decrease and eventually cause a shutdown at the MGDP due to the inability to drain the concentrate sump. This MGDP Concentrate Conditioning Project installs a 93% sulfuric acid chemical feed system to integrate continual concentrate conditioning by injecting the chemical into the brine to reduce the potential for scale to form in the disposal pipeline. The southern portion of the existing Mocho Well No. 4 building, which is located within the secured footprint of the Mocho Groundwater Demineralization Plant (MGDP), would be demolished and rebuilt, and a new roof would be installed over the full building to comply with current seismic code requirements. The rebuilt building portion would be approximately 625 square feet and would be within the same footprint of the existing well house, and building height would be similar to the existing MGDP roofline. Color schemes would match the existing colors currently on the same building. Portions of the asphalt concrete accessways would be reconstructed, and a new concrete pad installed for chemical delivery with piping to a chemical containment sump. The project also includes a new steel chemical storage tank, chemical metering pumps, concentrate sump pumps, control panels, variable frequency drives, various appurtenances, and electrical and controls modifications, which would be housed within the buildings onsite. It also includes piping, valves and related appurtenances, paint, chemical resistant coatings, lighting and other minor yard and interior work as required to complete the project. Typical construction equipment is expected to be used including, but not limited to: ? Concrete mixer, asphalt grinder, asphalt paver ? Excavator, crane, forklift, backhoe, skid steer, loader, dump truck ? Scaffold, lighting, ladders, and other safety equipment ? Various hand and power tools Standard BMP’s expected to be employed include, but are not limited to: ? Protect interior building drains to prevent pollutants from entering ? Protect exterior parking lot catch basins to prevent pollutants from entering ? Comply with noise limits and working hours required by the City of Pleasanton Municipal Code construction ? Temporary screening on fencing ? Dust control Construction is entirely within the existing footprint of the Mocho Groundwater Demineralization and Mocho Well No. 4 property. Typical daily construction traffic to and from the property is expected to include approximately fifteen to twenty workers and inspectors in personal or company vehicles, and 20 to 30 deliveries of equipment or construction materials. Minimal additional traffic is expected due to the project. A traffic control plan will be submitted to City of Pleasanton for approval prior to any needed lane closures. Construction staging and parking (both construction and personal vehicles) will be within the site boundary, unless a City of Pleasanton Encroachment Permit, or other formal approval by property owner is secured for offsite use. Construction is expected to occur over about eighteen months in 2022 and 2023. Work hours and noise limits will be in accordance with City of Pleasanton Municipal Code requirements for construction.

Contact Information

Elke Rank
Agency Name
Zone 7 Water Agency
Job Title
Assoc Water Resources Planner
Contact Types
Lead/Public Agency


Cross Streets
5215 Stoneridge Drive
Total Acres

Notice of Exemption

Exempt Status
Categorical Exemption
Type, Section or Code
Reasons for Exemption
? There will be minimal native ground disturbance. ? The project site is contained within an existing industrial-type setting and has been previously disturbed for construction of both the MGDP and Mocho Well No. 4 ? The project will have minimal construction-related nuisances to local residents, businesses, or recreational areas, such as disruptions to traffic and increased noise or dust, etc. ? The project site will look and function the same (or nearly) as it has in the past. ? There will not be any cumulative impacts because there are no successive projects of the same type and in the general same place, over time. ? Best Management Practices will be employed during construction to reduce the potential for localized erosion or impact to water quality. ? No impacts to sensitive habitat or wildlife are expected. ? Pre-construction biological surveys will be performed as needed. ? There is not a reasonable possibility that the project could result in a significant impact.
County Clerk


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