At our last board meeting we realized we hadn’t posted an update on the goings on related to our planning grant since May. So Mary Young, our President, put this report together:
We are moving forward on our planning grant. You may have seen our geotechnical engineer performing soil boring operations or maybe you saw our surveyors setting control for an aerial topographic survey. This is all part of the design of over $10,000,000 in system improvements.
Construction of these improvements will be funded through a construction grant. Both the planning and construction grants are funded by the State of California Division of Financial Assistance program for the Drinking Water State Revolving Fund program.
The figure below shows the improvements currently being designed and a list of the improvements is also shown in the table at the end of this post:
Here is a brief summary of the benefits of the Project:
–Replaces existing pipelines most vulnerable to failure, dramatically reducing lifetime O&M costs associated with pipeline repair.
–Addresses all recommended hydraulic improvements, achieving dramatic improvements to available fire flows and increased turnover of Pleasant Valley Tank.
–Increases system reliability by placing the Pleasant Valley Tank feed pumps at the water treatment plant, where a standby propane generator can provide power during a utility outage.
–Provides two tiers of disinfectant byproduct (DBP) control approaches: source control at the water treatment plant (via removal of DBP precursors in GAC reactors, as well as potential improvements to the performance of the DBP precursor removal in the raw water storage / settling tank); and mixing and ventilation at the Pleasant Valley Tank to promote volatilization and removal of a fraction of DBPs.
We are excited to continue working with our engineers on the design of this project as well as working with our partners at the State to complete the construction grant application.
Evaluation of MWC’s water treatment and distribution systems has resulted in the following list of recommended infrastructure improvements:
—Pipeline Replacement. Approximately 17,700 lineal feet (LF) of existing pipelines are recommended for replacement. Replacement pipeline diameters generally range from 6 inches to 10 inches. Segments of replacement piping are placed into three groups based on their relative priorities (i.e., Priority 1, Priority 2 and Priority 3 pipelines). Existing service connections and fire hydrants would be replaced along segments of replaced piping. Several new fire hydrants would be included to improve fire protection and assist with unidirectional flushing of the distribution system.
—Relocation of Pleasant Valley Pump Station. The existing pump station would be relocated to MWC’s water treatment plant (WTP) to allow electrical backup of the pumps by the standby propane generator MWC has recently installed, and to make room for a new pressure reducing station in the general location of the existing pump station.
—New Pressure Reducing Station. A new pressure reducing station would facilitate a reconfiguration of the existing MWC distribution system, allowing the downtown Markleeville area to be fed by water stored in the Pleasant Valley Tank. This change would increase turnover of the tank, thereby reducing water age and improving water quality in parts of the distribution system. Additionally, this change, when coupled with pipeline replacements, will dramatically improve flows to hydrants in the downtown area during a fire event.
—Granular Activated Carbon (GAC) Reactor Vessels at WTP. New GAC reactor vessels would be installed at the WTP to provide additional removal of DBP precursor material before finished water enters the distribution system. The vessels would be configured to allow bypassing during periods in which DBP precursor materials easily managed by existing WTP operations.
—Tank Mixing Equipment at Pleasant Valley Tank. New mixing equipment would be installed inside the existing tank to promote volatilization and removal of certain DBP species, thereby reducing DBP concentrations in the distribution system. Ventilation equipment would also be installed to promote exchange of tank headspace and facilitate removal of volatilized DBPs.
—Replacement Storage Tank(s) at WTP. Replacement of one or more existing tanks at the WTP may be required to accommodate the relocation of the Pleasant Valley Pump Station and the installation of new GAC reactor vessels. Each of the WTP’s existing tanks are over 30 years old and have reached the ends of their useful lives. If the raw water storage tank is replaced, improvements to chemical injection, clarification, and solids removal capabilities may be incorporated to increase removal of DBP precursor material and reduce the quantity of solids reached the WTP’s existing pressure filters.
Relative priorities for the above improvements are presented in Table 1-1 below:
|Table 1-1. Relative Priorities of Recommended Improvements|
|Improvement Element / Proposed Bid Item||Priority (1 = highest priority)|
|Priority 1 Pipeline Replacement and Affiliated Service Connections and Hydrants||1|
|Relocate Pleasant Valley Pump Station||2|
|New Pressure Reducing Station||3|
|Priority 2 Pipeline Replacement and Affiliated Service Connections and Hydrants||4|
|GAC Reactor Vessels at WTP||5|
|Replacement Storage Tank(s) at WTP||6|
|Tank Mixing Equipment at Pleasant Valley Tank||7|
For previous posts on this subject you can search “grant” or “planning grant” on our home page.
If you have any questions, please don’t hesitate to email us at firstname.lastname@example.org.