2. PUBLIC COMMENT / ORAL COMMUNICATION B. Discuss SRT 25% Design Task …1307B359-C05A-436D-AC1… · The City requested that each task be completed, reviewed, ... delivery; develops

CCWD and SAM Joint Recycled Water Committee

7:00 PM, Monday, January 30, 2017

Sewer Authority Mid-Coastside, 1000 Cabrillo Hwy N., Half Moon Bay, CA 94019

1. CALL TO ORDER / ROLL CALL

2. PUBLIC COMMENT / ORAL COMMUNICATION

3. OLD BUSINESS

4. NEW BUSINESS

A. Approve Minutes of October 17, 2016 Meeting

B. Discuss SRT 25% Design Task 1 – Alternative Analysis Report

C. Discuss CCWD Board Meeting of November 8, 2016 Regarding Recycled Water

Production Capacity

D. ADJOURNMENT

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INFORMATION FOR THE PUBLIC

This agenda contains a brief description of each item to be considered. Those wishing to

address the Committee on any matter not listed on the Agenda, but within the jurisdiction of

the Committee, may do so during the Public Comment section of the Agenda and will have a

maximum of three minutes to discuss their item. Those wishing to speak on a matter listed on

the Agenda will be called forward at the appropriate time.

Any writing that is a public record and relates to an agenda item for an open session of a

regular meeting, that is distributed to the Committee less than 72 hours prior to the meeting, is

available for public inspection, during normal business hours, at the address listed above.

Committee meetings are accessible to people with disabilities. Upon request, this agenda will

be made available in appropriate alternative formats to persons with a disability. In compliance

with the Americans with Disabilities Act, special assistance for participation in this meeting can

be obtained by contacting Kathy Matthews at (650) 726-0124. Request for a disability-related

modification or an accommodation in order to participate in the public meeting must be made

at least two working days in advance of the meeting.

MINUTES

CCWD & SAM JOINT RECYCLED WATER COMMITTEE MEETING

October 17, 2016

CALL TO ORDER: The meeting came to order at 7:06 p.m. at the SAM Administration

Building, located at 1000 N Cabrillo Highway, Half Moon Bay, CA.

PRESENT: Beverli A. Marshall (SAM General Manager), Kishen Prathivadi (SAM Engineering

Construction and Contracts Manager), Clemens Heldmaier (MWSD), Bill Huber (MWSD), Scott

Boyd (SAM Board), Ric Lohman (SAM Board), Ken Coverdell (CCWD), Glenn Reynolds

(CCWD), Deborah Penrose (HMB), Debbie Ruddock (SAM Board), Bruce Russell (OCP),

Dave Dickson (CCWD), Mary Rogen (CCWD)

2. PUBLIC COMMENT/ ORAL COMMUNICATION - NONE

3. OLD BUSINESS

A. Update on SRT 25% Design

Beverli Marshall, SAM General Manager, updated the committee on the progress of the

concerns from the City of Half Moon Bay regarding reverse osmosis. She informed the

committee that SRT has provided the information requested by Half Moon Bay, it was

discussed by the SAM Board, and the Board concurred that it should be submitted to Half

Moon Bay for their consideration. The City of Half Moon Bay still had some concerns but did

approve a portion of the proposal. The City requested that each task be completed, reviewed,

and approved before authorizing SRT to move to the next task. Ms. Marshall also informed the

committee that Half Moon Bay would like to contribute to an outreach program that would keep

the public informed on the progress of the project.

4. NEW BUSINESS

A. Approve Minutes of August 15, 2016

Following a brief discussion, Ric Lohman moved and Bill Huber seconded the motion to

approve the minutes of the August 15, 2016 Joint Recycled Water Committee meeting.

B. Agreement/Guiding Principles – SAM/CCWD/OCP

Glenn Reynolds stated that once the numbers are in for what the cost of the 25% design will

be, the next step will be evaluating the financial viability and how to structure it. He said that

the two parts to making the project viable are: (1) what costs will be shared by whom and (2)

what are the costs.

He stated that it would be timely to put together an outline of the contracts and suggested that

the two agencies involved, SAM and CCWD, have a Memorandum of Understanding (MOU)

for the contract and then CCWD will have to prepare a similar document with its potential

customers. A discussion ensued. Glenn Reynolds reminded the committee that copies of

CCWD & SAM RWC Minutes of October 17, 2016

Page 2 of 3

sample contracts are in the shared Google Docs folder that they all have access to. He also

suggested that the committee start by breaking it in to the various topics, (i.e. an exit strategy

and current costing). He also stated that he is more comfortable with a contract that works for

either water purveyor than one that is unique to each one.

Ric Lohman suggested starting with a couple of people from each agency to get something

going and get the basic stuff out as fast as possible instead of too many people working in the

Google Doc file at the same time. Ken Coverdell stated that the committee should direct

CCWD and SAM staff to work together on the agreement/guiding principles as a private

document rather than a public one. Glenn Reynolds suggested volunteering time to help staff

work on assigned tasks that might otherwise tie up a lot of time and energy. A discussion

ensued.

Bill Huber (MWSD), stated that he felt the idea of staff working up a contract for the committee

to evaluate is the proper way to do it. Bruce Russell (OCP), reminded the committee that he

had circulated a supplemental outline of some of the things that OCP would be focused on and

a basic contract that was signed between San Francisco and three golf courses that would be

a really good starting point. He stated that it was not too complex but addressed a lot of issues.

He also stated that he is assuming when the committee talks about developing some kind of

term sheet between SAM and CCWD, it would not hurt to be developing it with OCP at the

same time because they are very inter-related contracts. He encouraged the committee to take

a look at that contract. Ric Lohman (GCSD) stated that he would like to see the sample of

contracts by the time SRT rolls in with their 25% design number.

Bruce Russell (OCP), suggested getting proposals from consultants to spearhead the

permitting process. He stated that OCP is moving forward and he envisions having the OCP

Engineers prepare a plan for dredging the ponds and a narrative that would entail time wise. A

discussion ensued. Deborah Ruddock (SAM Board) stated that she would like to see a term

and term sheet that says all parties will make best faith efforts to move the project along in a

timely manner and actually agree to that term so there is no conflict later. Ric Lohman (GCSD)

asked that the committee keep in mind everyone’s meeting schedules and to also keep in mind

their next approval sequences ahead of time so things will keep moving along. Ken Coverdell

(CCWD) felt it would be a great idea to form a sub-committee of experienced project managers

to put together a timeline.

C. Next Steps for Joint SAM/CCWD Recycled Water Committee

Glenn Reynolds (CCWD) stated that one of the things the group should work on is to start

identifying the benefits of the project and the roles of the citizens on the committee to start

working on the citizen perception and what the direct citizen benefits are and asked that the

committee take that as a task. The committee agreed that it is important to keep the public

CCWD & SAM RWC Minutes of October 17, 2016

Page 3 of 3

apprised. The committee concurred that the next Joint Recycled Water Committee meeting will

be held on November 21, 2016.

5. ADJOURNMENT

The meeting was adjourned at 7:59 p.m.

Respectfully submitted,

Beverli A. Marshall

General Manager

SEWER AUTHORITY MID-COASTSIDE

Recycled Water Project Final Alternatives Analysis Technical Memorandum

SRT CONSULTANTS 1-24-2017

SEWER AUTHORITY MID-COASTSIDE RECYCLED WATER PROJECT FINAL ALTERNATIVES ANALYSIS TECHNICAL MEMORANDUM January 24, 2017

Page | ES-1

EXECUTIVE SUMMARY The Sewer Authority Mid-Coastside (SAM) retained SRT Consultants to provide an Alternatives Analysis

Technical Memorandum (TM) that updates and refines previous Recycled Water Project (RWP) analyses

pursuant to updated Ocean Colony Partner (OCP) requirements and SAM wastewater treatment plant

(WWTP) limitations. This TM evaluates concepts for siting of recycled water treatment, storage, and

delivery; develops preliminary site layouts; presents an alternative analysis matrix; and recommends a

preferred alternative.

The proposed RWP would be designed to meet the following recycled water demand requirements for

OCP:

Average Demand = 550,000 gallons per day (gpd)

Peak Demand = 800,000 gpd.

Table ES-1 presents the recycled water quality characteristics to minimize impacts to existing landscaping:

Table ES-1: Recycled Water Quality Requirements

Parameter Limit

pH Range 6.5-7.5

TDS (mg/l) ≤700

Electrical Conductivity (dSM) ≤1.1

Boron (mg/l) ≤1.0

Chloride (mg/l) ≤100

Sodium (mg/l) ≤70

Adjustable Sodium Adsorption Rate (aSAR) ≤3.0

BiCarbonate HCO3- (mg/l) ≤250

The proposed RWP requires the following new facilities:

Secondary Effluent Diversion Pipeline to convey secondary effluent from the secondary clarifier

to recycled water treatment.

Secondary Effluent Equalization Basin to store secondary effluent to accommodate diurnal flow

variations to provide a constant influent flow to recycled water treatment processes. The existing

primary clarifier No. 4 is proposed to be rehabilitated to a total volume of 160,000 gallons.

UF/RO Treatment to provide membrane filtration to meet recycled water treatment

requirements.

Brine (RO Concentrate) Disposal to convey RO Concentrate from recycled water treatment to the

existing ocean discharge disposal.

Ultraviolet treatment to sterilize recycled water to protect public health and meet regulatory

requirements.

Partially enclosed structure to protect treatment facilities.


Page | ES-2

Recycled Water Storage, Pumping, and connection to existing distribution system at OCP to store

produced recycled water to accommodate diurnal recycled water demand requirements and

pumps recycled water to customer’s existing infrastructure. The existing aeration basin No. 2 is

proposed to be rehabilitated to a total volume of 260,000 gallons.

Ancillary support systems including membrane cleaning, systems, automation, power

distribution, and supervisory control and data acquisition (SCADA) integration.

The tertiary treatment facilities consisting of the UF/RO skid-mounted treatment system, ancillary support

systems, and UV disinfection is recommended to be located on top of the existing primary clarifier No. 4

that would be rehabilitated to a secondary effluent equalization basin. This location is recommended

because it provides least impacts to the existing SAM WWTP site plan and operations, allowing continued

use of existing parking and storage facilities. Additionally, this location minimizes pipeline length and

construction impacts for onsite pipelines.

The recycled water distribution pipeline to connect to existing OCP facilities is recommended to be

constructed via horizontal directionally drilled tunneling techniques underneath Pilarcitos Creek to the

existing OCP well field. This pipeline alignment and construction technique is recommended to minimize

the pipeline length, as well as construction schedule.

Figures ES-1 and ES -2 present the recommended RWP facilities.


Page | ES-3

Figure ES-1: RWP Facilities


Page | ES-4

Figure ES-2: Rendering of Proposed UF/RO Treatment Systems


Page | 1

PURPOSE AND BACKGROUND This Alternative Analysis Technical Memorandum (TM) presents project alternatives for the Sewer

Authority Mid-Coastside (SAM) Recycled Water Project (RWP).

The SAM Board of Directors has established the objectives of the SAM RWP to:

Utilize SAM’s secondary treated wastewater effluent for beneficial use

Facilitate reduction of water draw on local aquifers

Facilitate reduction in ocean discharge of treated wastewater

Increase available instream water supply to Pilarcitos Creek, and

Secure irrigation water supplies for the Ocean Colony Partners (OCP).

The RWP implementation would diversify the region’s current water resources portfolio and create a

more sustainable watershed by reducing dependency on imported water supplies, as well as pumping

draws on the local groundwater aquifer. Reduction of well pumping may potentially improve flows in

Pilarcitos Creek, restoring aquatic habitat, and supporting the fragile coastal environment of the Midcoast

region.

The concept of recycled water production and use has been considered by SAM since the late 1990’s.

Initial planning of the RWP started in 2006. A Facility Planning Grant from the State Water Resources

Control Board was awarded to SAM in 2010 for the completion of a Recycled Water Facility Plan Report.

The Facility Plan Report completed in December 2010, and updated in August 2015 by SRT Consultants,

recommended a recycled water project that included new tertiary treatment facilities at the SAM

Wastewater Treatment Plant (WWTP) site to provide recycled water for irrigation purposes at the Ocean

Colony Golf Courses (OCGC). In addition, a source water control study was completed by SAM in

December 2015 that identified contributors of high chloride and salinity loading patterns to the SAM

WWTP.

The 2008 Pilarcitos Integrated Watershed Management Plan (San Mateo County Resource Conservation

District (RCD), 2008) identified recycled water development as a Priority Project within the RCD to improve

Pilarcitos Creek flows.

Additional studies were completed by Coastside County Water District (CCWD) in 2015 that refined

recycled water demands and water quality requirements for OCP.

This Alternatives Analysis updates and refines previous RWP analyses pursuant to updated OCP

requirements and SAM WWTP limitations. This study includes evaluation based the production, storage,

and delivery of 550,000 gpd of average day demand with 800,00 gpd of maximum day demand as

described in technical memorandums provided by CCWD. This study includes the following required RWP

elements:

MF/RO treatment

Pilarcitos Creek Pipeline Crossing


Page | 2

This study is based upon the following assumptions and limitations:

Estimated recycled water demands (quantity and timing) and water quality parameters provided

Existing survey information was used.

Existing water quality information was used.

Existing WWTP record drawings were used.

This study evaluates concepts for siting of recycled water treatment, storage, and delivery; develops

preliminary site layouts; presents an alternative analysis matrix; and recommends a preferred alternative.

EXISTING CONDITIONS

Existing Wastewater Treatment The SAM WWTP provides secondary wastewater treatment for the coastal communities of Montara, El

Granada, and Half Moon Bay. The treatment train includes screening, grit removal, primary

sedimentation, aeration, secondary clarification, disinfection, and dechlorination. Influent flow rate is

measured at the headwords with a Parshall flume. Wastewater then passes through bar screens for initial

solids removal. Eight variable-speed-drive pumps convey wastewater to two grit removal tanks.

Wastewater is then treated through primary sedimentation basins, aeration basins, secondary clarifiers,

and chlorine contact basins. Treated wastewater, or 3-Water, is recycled from the effluent pump station

back through the treatment process for in-plant use.

Existing Wastewater Flows and Quality Influent flows to the SAM WWTP vary depending on weather conditions and time of day. The SAM WWTP has a hydraulic capacity of 15 million gallons per day (mgd), with an average influent flow of 3.7 mgd. The average influent flow between September 2015 and September 2016 was estimated at 1.45 mgd. Influent flows have been decreasing due to increased water conservation practices and member agencies’ collection system Infiltration/Inflow (I/I) improvements. Figure 1 presents a summary of historical WWTP influent flow data. Figure 2 presents a summary of average diurnal WWTP influent flow data during the irrigation months of April – October.


Page | 3

Figure 1: SAM 2015-2016 WWTP Influent Flow

0.0

0.5

1.0

1.5

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2.5

3.0

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Sep-15 Oct-15 Nov-15 Dec-15 Jan-16 Feb-16 Mar-16 Apr-16 May-16 Jun-16 Jul-16 Aug-16 Sep-16

FLO

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SAM WWTP 2015-2016 INFLUENT

Influent Average (1.45) Influent


Page | 4

Figure 2: WWTP Average Diurnal Flow

Secondary effluent quality is monitored to meet Regional Water Quality Control Board (RWQCB) requirements. Table 1 provides a summary of SAM’s secondary effluent quality monitoring data.

Table 1: SAM Secondary Effluent Water Quality

Parameter Unit Annual Minimum

Annual Average

Annual Maximum

Permit Limit

TSS mg/L 3.0 8.5 18.0 30

BOD mg/L 4.7 12.5 38.0 30

Turbidity NTU 1.8 5.5 11.0

Nitrogen as Ammonia mg/L 3.0 30.5 46.0

pH 6.8 7.2 7.4

Temperature oC 17.1 20.9 24.4

Dissolved Oxygen mg/L 5.1 5.8 7.9

0.00

0.50

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2.50

WW

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flu

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(MG

D)

Apr - Oct Average Influent Flow Diurnal Curve


Page | 5

CUSTOMER DESCRIPTION OCP owns and operates two golf courses and the surrounding golf course community encompassing approximately 500 acres. The OCP irrigation system services approximately 210 acres. The following areas are irrigated: two OCP golf courses, Ritz Carlton Resort landscaping, a condominium complex adjacent to the Ocean Colony subdivision, greenbelt areas within the Ocean Colony subdivision, Miramontes Point Road landscaping, and Spyglass subdivision park. The current irrigated acreage represents a 75 reduction in irrigated land since 2008, based on the OCP’s significant work on redesign and conversion to native, less water-intensive grasses.

Existing Water Sources & Infrastructure OCP obtains irrigation water from the following three sources:

A well field owned by OCP located 2.15 miles north of the OCGC,

Potable water from CCWD, and

Runoff collected from the surrounding properties stored in ponds on the OCP property.

The well field is the primary source of irrigation water for OCP. In 2014, 66 percent of OCP’s irrigation

water was from their well field, local runoff, and precipitation accumulated on-site. The remaining 34

percent of OCP’s 2014 irrigation water demand was purchased from CCWD. OCP expects that future well

and pond improvements, and ongoing water conservation measures, will further reduce demand for

purchased water from CCWD.

The well field consists of five wells drawing from the Pilarcitos Creek aquifer near the mouth of the creek.

An existing irrigation pipeline conveys groundwater from the wellfield to OCGC. OCP stores irrigation

water in three unlined irrigation ponds located on the golf course. Per OCP, the total storage volume of

the three ponds is approximately 9 million gallons. Sedimentation has reduced the total storage capacity

to approximately 6.1 million gallons. Future dredging of the ponds is considered by OCP to increase on-

site storage capacity. This Alternatives Analysis assumes that the OCGC has 9 million gallons of on-site

storage available in their ponds.

OCP has two potable water meter connections from CCWD. Potable water is used to fill the irrigation

ponds and flush the turf-grass to remove salts that have accumulated in the soil as a result of regular

irrigation with the brackish-quality groundwater supply.

Irrigation Demand OCP provided an estimate of their total average and peak daily irrigation water demand at approximately

550,000 gallons per day (gpd) and 800,000 gpd, respectively. OCP’s irrigation water demand varies

seasonally, as presented in Table 2. The peak irrigation season occurs between March and November,

with greatest demand in the summer months between May and September, and varies each year

depending on rain patterns.


Page | 6

Table 2: OCP Irrigation Demand

Month Average Demand (Gallons per Day)

January 0

February 0

March 91,449

April 381,246

May 552,896

June 571,325

July 552,896

August 552,896

September 533,309

October 368,597

November 94,497

December 0

Source: CCWD, 2015

Quality Requirements In addition to meeting the California Code of Regulations (CCR) Title 22-compliant tertiary unrestricted

use requirements, OCP requires recycled water quality parameters consistent with the tolerance of the

most sensitive plant species intended for irrigation. Water quality should be produced that is low in

sodium, chlorides, has a low sodium adsorption ratio (SAR), and is not toxic to plants and grasses.

Salinity is a measure of the soluble salt concentration in water or soils. The salinity of a water sample is a

measure of its Total Dissolved Solids (TDS). TDS is measured in mg/L, parts per million (ppm), or as a

function of electrical conductivity (EC). Dissolved solids, added from various sources during domestic and

other water uses are generally not reduced during conventional wastewater treatment and recycling

processes. Thus, recycled water generally has a higher TDS concentrations than potable water that was

its source. As salinity levels increase, irrigated plants need to use more energy to concentrate solution in

root cells allowing them to take up water from the soil for growth and transpiration. High salinity levels

result in plant growth reduction and observable symptoms similar in appearance to drought conditions.

OCP specified the following water quality criteria to ensure protection of turf species listed in Table 3.

Table 3: OCP Irrigation Water Quality Requirements

Parameter Limit

pH Range 6.5-7.5

TDS (mg/l) ≤700

Electrical Conductivity (dSM) ≤1.1

Boron (mg/l) ≤1.0

Chloride (mg/l) ≤100

Sodium (mg/l) ≤70

Adjustable Sodium Adsorption Rate (aSAR) ≤3.0

BiCarbonate HCO3- (mg/l) ≤250


Page | 7

FACILITY DESIGN CRITERIA Technical memoranda provided by CCWD presented the customer irrigation demands and water quality

requirements that determined the treatment plant sizing and treatment technology. OCP’s peak day

demand of 0.8 mgd is used to determine the recycled treatment facility capacity. Evaluation of effluent

water quality from the existing secondary treatment facilities at SAM WWTP in relation to the low sodium

water quality requirements of OCP determined that Reverse Osmosis (RO) treatment would be required

to meet the low sodium water quality requirements.

The RWP analysis developed in the following sections is based on 0.8 mgd peak-day demand, 0.6 mgd

average demand, 8-hour irrigation period, and Ultrafiltration/Reverse Osmosis (UF/RO) tertiary

treatment. A 48-percent RO treatment blend was determined by CCWD to be required to meet OCP’s

required water quality. Further confirmation of RO treatment blend would be required during the project

design phase. Treatment facilities would be designed to include additional space for housing additional

vessels to allow for simplified potential future expansion to treat all of the SAM WWTP influent.

The RWP facilities include the following components:

Secondary Effluent Diversion – Conveys secondary effluent from the secondary clarifier to

recycled water treatment.

Secondary Effluent Equalization Basin – Stores secondary effluent to accommodate diurnal flow

variations to provide a constant influent flow to recycled water treatment processes.

UF/RO Treatment – Membrane filtration to meet recycled water treatment requirements

RO Concentrate Disposal – Convey RO Concentrate from recycled water treatment to ocean

discharge disposal

Disinfection – Ultraviolet treatment to sterilize recycled water to protect public health and meet

regulatory requirements.

Recycled Water Storage, Pumping, and connection to existing distribution system at OCGC –

Stores produced recycled water to accommodate diurnal recycled water demand requirements

and pumps recycled water to customer’s existing infrastructure.

Ancillary support systems including membrane cleaning, systems, automation, power

distribution, and supervisory control and data acquisition (SCADA) integration.

Figure 3 presents a process flow diagram of the proposed RWP facilities.

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Figure 3: RWP Process Flow DiagramPage | 8


Page | 9

UNIT PROCESS CAPACITIES The following information formed the basis of determining the most efficient treatment rate for the RWP:

SAM dry weather flow data,

Available storage volumes, and

OCP demands.

To provide the maximum daily volume of irrigation water to OCP while utilizing existing on-site storage

facilities, tertiary treatment production would operate 24 hours per day during the peak demand period.

Recycled water pump station would operate up to 18 hours per day, depending on irrigation demand

conditions. Table 5 presents RWP Facility Capacities. Appendix A presents the treatment plant flow

equalization model.

Table 5: RWP Facility Capacities

Description Quantity Units

Average Annual Demand 308,000 gpd

Average Irrigation Season Day Demand 550,000 gpd

Irrigation Season Peak Day 800,000 gpd

Secondary Effluent Equalization Volume 160,000 gallons

UF/RO Treatment Plant Influent 1,000,000 gpd

RO Concentrate Discharge 200,000 gpd

Recycled Water Clearwell Volume 260,000 gallons

Recycled Water Clearwell Pump Flow 740 gpm

SECONDARY EFFLUENT DIVERSION Secondary effluent would be diverted to equalization storage through a new approximately 180-foot-long,

8-inch-diameter pipeline to the existing unused primary clarifier No. 4 re-purposed as an equalization

basin. Secondary effluent would be conveyed from either Secondary Clarifier No. 1 or 2, depending on

which unit was in operation. Pre-chlorinated secondary effluent would flow by gravity to the new

secondary effluent storage. The secondary clarifiers would be modified to accommodate a new pipeline

and appurtenances to convey the secondary effluent to the re-purposed equalization basin.

SECONDARY EFFLUENT EQUALIZATION STORAGE The UF/RO treatment facility must operate at a constant rate, therefore, storage of secondary effluent

prior to tertiary treatment is required to compensate for fluctuations in diurnal influent flows. Existing

infrastructure not being used has been evaluated for storage capacity to minimize cost for new facilities.

The existing 125,000-gallon primary clarifier No. 4 would be renovated for secondary effluent storage to

a volume of 160,000 gallons. The secondary effluent would be pumped from the equalization storage

facility to the new UF/RO treatment system.


Page | 10

UF/RO TREATMENT The UF/RO treatment skid-mounted treatment units, disinfection unit, and necessary appurtenances will

be contained in the available area at the SAM WWTP, with the goal to effectively utilize the available

space. The treatment facilities would be covered to prevent deterioration due to the elements.

Multiple options and configurations exist from various UF/RO membrane manufacturers. However, the

basic treatment process remains the same. UF treatment and RO treatment may be standalone processes,

or they may be integrated units. Because of the relatively small treatment capacity and limited available

construction footprint, an integrated UF/RO system is recommended for the RWP. The benefits of an

integrated package system ensure compatibility of both systems and simplified operations and

maintenance requirements. Integrated systems also simplify design and construction. UF processes may

be a pressure membrane configuration or submerged within stainless steel tanks. To minimize

construction time and cost of tanks, as well as simplified operations and maintenance, the UF pressure

membrane configuration is recommended for the RWP.

The treatment systems are modular and additional units may be added for future potential expansion.

Figures 4 and 5 present examples of UF/RO equipment. Further analysis and selection of specific

equipment and manufacturers will be completed as part of future RWP tasks.

The RW facility footprint, at about 1,500 square feet, would have sufficient room for personnel to operate

and maintain the equipment. Alternatives for facility siting are presented below.

Figure 4: Example Integrated UF/RO Unit (Source: GE)


Page | 11

Figure 5: Example UF/RO Layout (Source: H20Innovation)

The main treatment processes at the facility include UF and RO. The secondary effluent is first pumped

from the equalization basin to a pre-treatment strainer where any larger particles are removed. From the

strainer, the water is passed through pressurized membrane filtration systems. The UF membranes’ pore

size is 0.01 microns, removing many particles, including some viruses, albeit no dissolved substances. RO

membranes have a pore size of 0.0001 microns and remove all organic molecules and viruses. RO also

removes most minerals that are present in the water. Based on previous analyses by CCWD, between 32

and 48 percent of tertiary treatment influent will need to be treated with RO to meet the OCP product

water requirements (Kennedy Jenks Consultants, 2016). For purposes of this analysis, 50 percent of the

recycled water is assumed to undergo RO treatment.

Air compression equipment, backwash equipment, and clean in place (CIP) equipment are also included

in the process treatment train as essential components of the membrane filtration system. The primary

waste stream from the facility, including the autostrainer backwash, UF maintenance wash, and CIP waste

streams will be conveyed back to the primary clarifiers. A break tank to hold backwash and provide

equalization is required between the MF and RO systems. The break tank is estimated to be

approximately 10,000 gallons.

RO Concentrate from the reverse osmosis system will be discharged through a separate RO concentrate

discharge pipeline to the existing effluent pump station downstream of the No. 3 water prior to discharge

through the ocean outfall. The RO concentrate would be chlorinated and dechlorinated prior to discharge

pursuant to regulatory requirements.

The UF/RO process would include in-line analyzers for water quality requirements.


Page | 12

DISINFECTION To meet Title 22 requirements, the recycled water will be disinfected after treatment. Typical mechanisms

for disinfection of recycled water are chlorine (chlorine gas, sodium hypochlorite, combined chlorine,

chlorine dioxide), ozone, and UV radiation. Disadvantages of disinfection by chlorine and related

compounds include increased space requirements, increased TDS levels, long contact times, hazardous

material, upset risk, and disinfection byproducts. Therefore, the shorter contact times, improved safety,

smaller required footprint, and disinfectant effectiveness make ozone and UV preferred methods of

sterilization for recycled water treatment on small sites such as at the SAM WWTP. UV does not require

chemical storage and forms no disinfection byproducts in comparison to ozone. Chlorination is required

for treated effluent that is to be recycled and/or stored in recycled water storage tanks. A UV system can

be used for sterilization of recycled water, but cannot provide the residual to prevent the re-growth of

bacteria or algae in the piping or storage tanks. A chlorination system can provide this residual. For this

project, UV is recommended for sterilization followed by disinfection with sodium hypochlorite.

The UV System would be located downstream of the RO system, but would also treat water from the UF

units. The UV system would be designed to treat UF filtrate quality water. UF/RO effluent would pass

through a UV sterilization system. A sodium hypochlorite addition system would be installed to provide

chlorine residual in the RW storage tank and distribution pipelines.

RECYCLED WATER STORAGE AND DISTRIBUTION

The existing 260,000-gallon aeration basin No. 2 would be renovated to provide operational storage of

recycled water. Because RO demineralizes water and is "aggressive" water with low pH that may

deteriorate concrete, remineralization of the recycled water with calcium or magnesium may be required

prior to storage depending on final water quality after blending. Remineralization may be required by

chemical addition prior to discharge into the storage tank. Further analysis of final product water quality

(following blending of RO and UF filtered waters) would be required to determine if remineralization is

required.

A 40-horsepower (Hp) pump station would pump up to 900 gpm of recycled water through a new

approximately 800-foot-long 12-inch-diameter pipeline to the existing OCP wellfield. From the well field,

it will connect to an existing 10-inch-diameter pipeline that would convey recycled water to OCP’s on-site

storage facilities. It is assumed pumping from the recycled water clearwell would occur over 18 hours

daily. The clearwell will be shaded or covered to minimize algal growth and maintain water quality.

ADDITIONAL TREATMENT PLANT IMPROVEMENTS REQUIRED The following improvements to existing SAM WWTP facilities would be required to implement the RWP:

Rehabilitation of Aeration Basin No. 4. Renovation of Aeration Basin No. 2 for the purpose of

recycled water storage reduces the available WWTP reliability and storage capabilities.

Therefore, Aeration Basin No. 4 would be rehabilitated to maintain plant reliability and

performance.

Generator replacement. The existing generator is original to the WWTP and is approximately 40

years old. Although the generator is of sufficient capacity to meet the power requirements of the


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RWP, replacement and upgrading of the generator is recommended for continued reliability and

performance.

Siting Alternatives The following alternatives have been considered for tertiary treatment facility siting:

1. On top of existing Primary Clarifier No. 4,

2. Adjacent to Aeration Basin No. 2, and

3. Adjacent to existing Mechanical Building No. 2.

Figures 6 through 8 present alternative site layouts of the RWP facilities that are evaluated as part of this

report.

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Figure 6: RWP Site Alternative 1Page | 14

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Treatment Siting Alternative 1 UF/RO treatment, sterilization, and disinfection would be constructed on skid-mounted units on top of

the existing concrete structure of primary clarifier No. 4. The site has approximately 1,500 square feet

available.

The proposed site plan for Alternative 1 is presented in Figure 6. Primary Clarifier No. 4 would be re-

purposed and rehabilitated as an equalization basin to store secondary effluent; secondary effluent would

be pumped to UF/RO treatment and disinfection constructed on top of the rehabilitated structure.

Following UF/RO and disinfection, recycled water would be conveyed by gravity through an approximately

35-foot-long pipeline to recycled water storage in existing Aeration Basin No. 2. Backwash and CIP waste

flows would be directed to Primary Clarifier No. 3 directly adjacent to the treatment system via an

approximately 6-foot-long pipeline. An approximately 320-foot-long RO concentrate/tertiary treatment

bypass pipeline from the Equalization Basin (re-purposed existing Primary Clarifier No. 4) to the Effluent

Pump Station would be routed through the existing pipe gallery, under the WWTP access road, and along

the external perimeter of the existing curb and retaining wall.

Treatment Siting Alternative 2 UF/RO treatment, sterilization, and disinfection would be located on skid-mounted units adjacent to the

existing aeration basins on the southeast side of the WWTP site. The site has approximately 2,800 square

feet available.

The proposed site plan for Alternative 2 is presented in Figure 7. Secondary effluent stored in Primary

Clarifier No. 4 would be pumped to UF/RO treatment adjacent to Aeration Basin No. 2 through an

approximately 65-foot-long pipeline. Following filtration and disinfection, recycled water would be

conveyed by gravity through an approximately 6-foot-long pipeline to recycled water storage in Aeration

Basin No. 2. Backwash and CIP waste flows would be pumped to Primary Clarifier No. 3 via an

approximately 90-foot-long pipeline. An approximately 480-foot-long RO concentrate/tertiary treatment

bypass pipeline from the UF/RO treatment site to the Effluent Pump Station would be routed north of

Aeration Basins Nos. 1 and 2 and Primary Clarifier No. 4, through the existing pipe gallery, under the

WWTP access road, and along the external perimeter of the existing curb and retaining wall.

Treatment Siting Alternative 3 UF/RO treatment, sterilization, and disinfection would be located on skid-mounted units adjacent to the

existing Mechanical Building No. 2 on the northwest side of the WWTP site. The site has approximately

2,080 square feet available.

The proposed site plan for Alternative 3 is presented in Figure 8. Secondary effluent stored in Primary

Clarifier No. 4 would be pumped to UF/RO treatment east of Mechanical Building No. 2 through a new

approximately 150-foot-long pipeline. Following filtration and disinfection, recycled water would be

pumped through an approximately 120-foot-long pipeline to recycled water storage in Aeration Basin No.

2. Backwash and CIP waste flows would be pumped to Primary Clarifier No. 3 through a new approximately

160-foot-long pipeline. An approximately 450-foot-long RO concentrate/tertiary treatment bypass

pipeline from the UF/RO treatment site to the Effluent Pump Station would be routed along the secondary


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effluent and recycled water pipeline to and from the UF/RO treatment site, through the existing pipe

gallery, under the WWTP access road, and along the external perimeter of the existing curb.

Recycled Water Distribution Alternatives The following alignment alternatives have been developed for recycled water distribution:

1. 800 linear feet of 12-inch-diameter pipeline crossing under Pilarcitos Creek using horizontal

directional drilling (HDD) technology, and

2. 1,900 linear feet of 12-inch-diameter pipeline crossing over Pilarcitos Creek from the existing

pedestrian bridge using conventional construction methods.

It is recommended that Alternative 1 be used as it is significantly shorter than Alternative 2.

Recycled Water Distribution Alternative 1 The proposed site plan for Recycled Water Distribution Alternative 1 is presented in Figure 9 and presumes

the shortest possible distance to feasibly cross under Pilarcitos Creek from an HDD receiving pit at the

southeast corner of the WWTP property to the OCP well field sending pit.


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Figure 9 - Distribution Alternative 1


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Recycled Water Distribution Alternative 2 The proposed site plan for Recycled Water Distribution Alternative 2 is presented in Figure 10. The 12-

inch-diameter recycled water pipeline would cross over Pilarcitos Creek attached to the existing

pedestrian bridge to minimize potential environmental impacts to the creek. Although this alternative

avoids HDD, it requires an additional 200 linear feet of pipeline construction within the WWTP site and an

additional 1,200 linear feet of pipeline outside of the WWTP. Due to the additional pipeline construction

required and the unknown capacity of the existing pedestrian bridge to support a 12-inch-diameter water

carrying pipeline, Alternative 2 is not recommended for further evaluation.

Figure 10: Distribution Alternative 2


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ALTERNATIVE EVALUATION Each alternative was evaluated based upon the following criteria:

Opportunity for Future Expansion: Sufficient area for additional facilities

Constructability

Operational Complexity

Environmental Impacts

Regulatory Requirements

Funding Potential

Table 6 presents an evaluation of the alternatives based upon the above criteria.

RECOMMENDED ALTERNATIVE The recommended RWP would be located at the SAM WWTP and make use of existing facilities. It is

assumed that re-purposing of existing facilities would not compromise existing regulatory permits. Siting

Alternative 1 and Distribution System Alternative 1 (UF/RO treatment located above the proposed

equalization basin, and distribution pipeline construction by HDD tunneling under Pilarcitos Creek) are

selected as the recommended Recycled Water Project due to the following considerations:

No reduction in existing parking or storage facilities,

Less pipeline construction requirements

Efficient use of existing space.

The recommended project would not impair existing parking, allowing current operations and

maintenance of vehicles to remain the same. Existing parking areas may be covered in the future to

protect vehicles from the elements. Construction of the recommended project requires less pipeline and

pumping of secondary effluent and product water. The recommended project also accounts for the least

capital cost of the alternatives. Operational costs of each alternative are generally the same and

therefore were not considered in the alternative selection.

The recommended project would include the construction of approximately 110 feet of secondary

effluent diversion pipeline, rehabilitation and re-use of primary clarifier No. 4 for use as a secondary

effluent equalization basin, covered UF/RO treatment, UV sterilization, approximately 320 feet of RO

concentrate discharge/bypass pipeline, rehabilitation and re-use of the existing aeration basin No. 2 for

use as recycled water storage, 1 duty and 1 standby recycled water pumps, and approximately 800 feet

of recycled water distribution pipeline. The project facilities would be designed to service existing OCP

irrigation demands. The use of recycled water would be landscape irrigation. Irrigation would primarily

occur between 10:00 p.m. and 6:00 a.m. to maximize water use efficiency and minimize public contact.

The potential to expand to future demands was considered, and is feasible with modular treatment

facilities; however, due to existing low wastewater influent flows, expansion potential is limited. Figure

11 presents a rendering of the proposed treatment system above the existing primary clarifier No. 4.


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Figure 11: Rendering of Proposed Treatment System


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Table 6: Alternatives Analysis Matrix

Alternative Expansion Potential Constructability Operational Complexity Environmental Impacts

Regulatory Requirements Funding

Siting Alt 1 There is limited potential for future expansion on top of the existing clarifier. However, additional treatment units could be placed on top of the adjacent clarifier. NOTE: Current and projected future WWTP flows limit RWP expansion potential beyond currently proposed 800,000 gpd.

Facilities could be constructed using conventional methods. Skid-mounted treatment facilities would be required to be anchored to meet building code requirements. In-plant pipeline construction may be congested.

The site is outside of existing operations and would not interfere with truck deliveries of maintenance. The equalization basin would be covered, requiring confined space entry for maintenance operations.

Reduced pumping from existing wells adjacent to Pilarcitos Creek would improve Creek conditions.

Revision to existing NPDES permit for ocean discharge may be required. Title 22 Engineering Report required for Recycled Water Use and Distribution.

Potential grant funding may be available from San Mateo Resource Conservation District and San Francisco Public Utilities Commission. Potential loan funding from SWRCB through SRF program.

Siting Alt 2 There is limited potential for future expansion. NOTE: Current and projected future WWTP flows limit RWP expansion potential beyond currently proposed 800,000 gpd.

Facilities could be constructed using conventional methods. In-plant pipeline construction may be congested. The alternative would remove existing parking facilities.

The site is adjacent to existing truck traffic routes. New parking facilities would be required.



Potential grant funding may be available from San Mateo Resource Conservation District and San Francisco Public Utilities Commission. Potential loan funding from SWRCB through SRF program.

Siting Alt 3 There is limited potential for future expansion. NOTE: Current and projected future WWTP flows limit RWP expansion potential beyond currently proposed 800,000 gpd.

Facilities could be constructed using conventional methods. In plant pipeline construction may be congested. The alternative would remove existing parking facilities.

The site is adjacent to existing truck traffic routes. New parking facilities would be required.



Potential grant funding may be available from San Mateo Resource Conservation District. and San Francisco Public Utilities Commission Potential loan funding from SWRCB through SRF program.

Distribution Alt 1 There is potential for future expansion.

Facilities could be constructed using HDD technology under Pilarcitos Creek.

Pipeline underneath the creek would be difficult to access.

Potential impacts to creek could occur during creek crossing construction, albeit unlikely.

A streambed alteration agreement is required.

Project costs included in above alternatives.

Distribution Alt 2 There is potential for future expansion.

Facilities could be constructed using conventional methods by hanging pipeline from the existing bridge. Approximately 1,500 LF additional pipeline length required. Additional time required for construction.

Existing bridge ability to carry the pipeline is unknown.

A streambed alteration agreement is required.

Project costs included in above alternatives.

2. PUBLIC COMMENT / ORAL COMMUNICATION B. Discuss SRT 25% Design Task …1307B359-C05A-436D-AC1… · The City requested that each task be completed, reviewed, ... delivery; develops

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