HomeMy WebLinkAbout03. Dublin San Ramon Services District – East Bay Municipal Utility District Recycled Water Authority (DERWA) Raw Wastewater Diversion Request 3■
Central Contra Costa Sanitary District
March 22, 2017
TO: REAL ESTATE, ENVIRONMENTAL & PLANNING POMMITTEE
/r
IIIA. ROGER S. BAILED GENERAL MANAGER
JEAN-MARC P TIT, DIRECTOR OF ENGINEERING &. TECHNICAL
SERVICES 3hP
PHILIP LEIBER, DIRECTOR OF FINANCE & ADMINISTRATION
DANEA GEMMELL, PLANNING & DEVELOPMENT SERVICES
DIVISION MANAGER
REVIEWED
BY: KENT ALM, DISTRICT COUNSEL
FROM: MELODY LABELLA, RESOURCE RECOVERY PROGRAM MANAGER
THOMAS BRIGHTBILL, SENIOR ENGINEER ffl�fvg,
DAN FROST, SENIOR ENGINEER 056 ;#.
SUBJECT: DERWA REQUEST TO DEVELOP A MEMORANDUM OF
UNDERSTANDING FOR A PILOT PROJECT TO DIVERT RAW
WASTEWATER FROM CENTRAL SAN'S SERVICE AREA FOR THE
PURPOSE OF PRODUCING RECYCLED WATER TO MEET DERWA'S
PEAK SUMMER IRRIGATION DEMAND
Introduction
Central San has received a written request (see Attachment 1) from the Dublin San
Raman services District (DSRSD) — East Bay Municipal Utility District (EBMUD)
Recycled Water Authority (DERWA) to develop a memorandum of understanding
(MOU) to explore a potential partnership and pilot project to divert a portion of the raw
wastewater from Central San's San Ramon Pump Station between May and September
every year. The wastewater would be diverted through DSRSD's existing collection
system to DSRSD's treatment plant, for the purpose of producing and distributing
recycled water to meet DERWA's peak summer irrigation demand. DERWA is now
making this request, because it has a need for a temporary supplemental supply to help
meet recycled water demands in the EBMUD and DSRSD service areas until
wastewater flows increase with development and other long-term options are identified.
Since exploring partnerships to augment the region's water supply is an important
strategic goal for Central San, this pilot project provides an excellent opportunity for
Central San to consider for expanding the beneficial reuse of its wastewater.
N:\ENG BOARD DOCS\Board Committee Meetings\REEP Committee\24171Marchl3-22-17 REEF Memo-DERWA Diversion
Rvsd.docx
Real Estate, Environmental and Planning Committee
March 22, 2017
Page 2of5
Background
DERWA created the San Ramon Valley Recycled Water Program (SRVRWP) in 1995,
and began delivering recycled water in early 2005. The SRVRWP consists of the
treatment, storage, and use of highly-treated recycled water for landscape irrigation
within parks of Dublin and San Ramon (see Attachment 2). The SRVRWP is being
implemented in several phases within the two Districts' existing service areas. Future
phases of the program will extend recycled water into other parts of the San Ramon
Valley, depending on supply and demand, capital funding needs and availability. The
SRVRWP is designed to provide up to 3,696 acre-feet (>1 billion gallons) perv ear of
recycled water to DSRSD, and up to 2,688 acre-feet (>875 million gallons) per year of
recycled water to EBMUD.
EBMUD and DSRSD take the recycled water from the DERWA backbone system and
provide it to recycled water customers in their respective service areas delivering it via
distribution pipelines. DSRSD currently supplies DERWA recycled water to parts of
Dublin and the Dougherty Valley, while EBMUD serves DERWA recycled water to
portions of San Ramon. In future phases, EBMUD will also supply areas within
Blackhawk and Danville. The SRVRWP's main transmission pipeline connects to
DSRSD and the EBMUD pipelines that serve large irrigation customers: golf courses,
parks, greenbelts, roadway medians, schools, office complexes, and common areas in
homeowner associations.
In 2014, the City of Pleasanton signed agreements with the SRVRWP partners that
allow its treated wastewater to be used to produce recycled water. The agreements
pave the way for a recycled water program in Pleasanton and expansion of the
SRVRWP water recycling plant. As the city of Pleasanton's recycled waterro ram is
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implemented, DERWA will face supply shortages, since the DERWA partners are
currently using the City of Pleasanton's wastewater to produce a portion of DERWA's
recycled water currently being used in DS RSD's and EBM U D's service areas. In an
effort to address the anticipated future shortage, DERWA first evaluated the concept of
diverting central San's raw wastewater flow in 2004.
Analysis
In considering the DERWA request to divert wastewater from Central San's service
area, staff identified potential benefits and issues of concern from such an arrangement.
The potential benefits are
• Expanded beneficial reuse of central San's wastewater
• Reduced treated wastewater discharges to Suisun Bay
• Preserving recycled water service to Central San's customers in San Ramon
Staff identified the potential consequences as:
■ Collection system and treatment plant impacts
• conflicts with Board recycled water goals
• customer and financial impacts
Real Estate, Environmental and Planning Committee
March 22, 2017
Page 3 of 5
Staff expands on the potential benefits and consequences below.
Potential Benefits
The DERWA diversion request seeks raw wastewater flow from the San Ramon Pump
Station, between the months of May and September. During that timeframe, the
average daily wastewater flow through that Pump Station is 2.5 million gallons per day
(MGD). By diverting that flow, an additional 2.5 MGD of Central San's wastewater will
be put to beneficial use, more than doubling the amount of recycled water produced
from Central San's wastewater. This would also mean a corresponding reduction in
treated wastewater effluent being discharged into Suisun Bay.
In addition, since EBMUD and DSRSD have been essentially "borrowing" wastewater
flow from the City of Pleasanton to meet the current.DERWA demand for recycled
water, now that the City of Pleasanton is developing their own recycled water program,
both EBMUD and DSRSD need to find additional supply to meet DERWA recycled
water demands in their respective service areas. Since EBMUD and DSRSD serve
recycled water to the southern portion of Central San's service area, the diverted
wastewater flow from the San Ramon Pump station could be viewed as preserving
recycled water service to current (and potentially future) Central San customers using
recycled water produced by DERWA.
Potential Consequences
Potential Physical Impacts — Collection System and Treatment Plant
Maintaining the functionality of Central San's collection system is an important
consideration in evaluating raw wastewater diversion requests. Due to dramatic
improvements in the water-use efficiency of indoor water fixtures, expanded graywater
use, and other water conservation efforts, Central San's base wastewater flows have
declined far more rapidly over the last 30 years than the collection system has been
replaced, resulting in many pipelines that are oversized for handling summer
wastewater flows. According to Central San's new calibrated dynamic collection system
hydraulic model, many of Central San's pipelines run below scouring velocity during dry
weather. The reduction in wastewater flow in an oversizedi e can lead to the settling
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of solids in the collection system resulting in increased potential for odors and corrosion,
stoppages, and other potential consequences on wastewater quality and downstream
treatment plant impacts that may not have been fully realized or fully correlated yet.
.The recent drought has provided insights into potential treatment plant impacts from
reduced wastewater flows. In 2014 and 2015, the average influent flow declined below
30 MGD for central San's treatment plant, which has a permitted capacity of 53.8 MGD.
Hourly flows throughout the day reduced to as low as 11.5 MGD during the summer.
This decline in flow presents operational challenges for facilities originally designed for
higher flows (inadequate turndown). So far, these challenges have not caused any
process shutdowns and staff has reliably maintained treatment performance and
compliance; however, it is important not to lose sight of potential unintended
consequences of further reducing flow to the treatment plant. When flows are already
Real Estate, Environmental and Planning Committee
March 22, 2017
Page 4of5
severely low and impacts of these low flows affecting treatment plant facilities are
already present, increased diversion of raw wastewater would exacerbate these issues.
Potential Conflict with Board Recycled Water Goals
During preparation of central San's Wholesale Recycled Water Opportunities Study
(Wholesale Study), the Real Estate, Environmental and Planning (BEEP) Committee
provided guidance to staff to favor the development of recycled water projects with large
yields and year-round demand. The DERWA diversion requests seeks a small volume
of Central San's raw wastewater to produce recycled water for seasonal irrigation
demand.
The Comprehensive Wastewater Master Plan carried forward the potential alternatives
from the Wholesale Study and included the facilities, locations, and costs, if Central San
were to pursue zero discharge of treated wastewater effluent during dry weather
conditions. Future potential recycled water projects include supply of up to 5.8 MGD of
recycled water to the Concord Reuse Project, up to 20 MGD of recycled water to nearby
refineries, and up to an additional 10 MGD of recycled water for an indirect or direct
potable reuse project.
To provide a reliable supply of recycled water to any of these Board-supported projects,
it is critical that adequate wastewater is available to those recycled water treatment
facilities. At the plant's already low hourly flows of 11.5 MGD, it will become challenging
to provide a reliable supply of treated wastewater to several treatment process trains
without triggering a significant increase in onsite storage facilities. Allowing additional
diversion of raw wastewater may unintentionally influence the unit cost, and therefore
the feasibility, of some of Central San's large, regional recycled water projects
envisioned at the treatment plant.
Potential Customer and Financial Impacts
Providing reliable wastewater service at equitable rates that comply with Proposition
218 creates a complex, interdependent system, where heavy capital investments are
required to rehabilitate and replace necessary infrastructure. Making a change to where
a customer's wastewater is ultimately treated has corresponding complex and
interdependent impacts. Staff has conducted a preliminary financial analysis of the
impacts to Central San from a potential diversion of 2.5 MGD of raw wastewater flow to
DSRSD for the purpose of producing recycled water for DERWA.
Geographic Information System (GIS)'data was analyzed to identify all of the parcels
which contribute flow to the San Ramon Pump Station. There are 12,864 billable
parcels, of which 11,161 are single-family residential, 16 are single family/multifamily
residential (30 residential unit equivalents (RUEs)}, 1,643 are multifamily residential
parcels (4,360 RUEs), and 44 are non-residential parcels (1,604 RUEs). Staff
estimates that there are roughly an additional 600-1,000 RUEs that could be added to
the sewershed flowing to the San Ramon Pump Station. The total 2015/2016 sewer
service charge (SSC) revenue to central San for the developed parcels is $8,559,973,
which represents 11.9% of Central San's total 2015/2016 SSC revenue. Property tax
Real Estate, Environmental and Planning Committee
March 22, 2017
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revenue associated with these parcels, which Central San directs to the capital
program, is another $1.4 million (the size of which would not vary from this loss of flow).
Dividing the $8,559,973 total SSC revenue by the 2015/2016 rate of $503 per single
family residence yields 17,018 RUEs, which is approximately 8% of the total flow at the
treatment plant. Central San staff identified the following treatment plant costs as
variable: grit removal, chemicals, utilities, and ash disposal. Based on 2015/2016 costs
and treated wastewater flows, these variable costs are.about $294 per million gallons.
Multiplying this figure by 2.5 MCD for 365 days results in an estimated variable cost of
$268,275 (3.13% of total SSC revenue from these parcels). Multiplying this by 5112 to
capture the May-- September timeframe requested, the variable costs would fall to
$111,781 (1.31% of total SSC revenue from these parcels).
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If revenues are to be shared with DSRSD for the treatment of the diverted wastewater
flow, $111,781 represents the upper limit of revenue that could be shared (assuming the
diversion doesn't cause additional operational expenses) without raising costs to other
Central San customers from having them bear the lost share of fixed cost recovery.
Alternatively, if the full SSC revenue associated with these flows were provided to
DSRSD, Central San's remaining customers would face a 13.1% increase (at 2.5 MCD)
in their SSC bills as a result. This would require Central San to increase its annual
charge from $503 to $569 (13.1%) per RUE to address revenue shortfalls.
Discussion
While Central San is highly supportive of expanding the beneficial reuse of its
wastewater, there are potentially significant consequences that could result from
diverting raw wastewater to DSRSD that need to be carefully considered. Alternatively,
the most optimal way for Central San to provide water supply to DERWA is through a
regional exchange. For example, Central San could provide recycled water to one or
both Martinez refineries and that freed water supply could be transferred to Zone 7, the
wholesale water retailer in the San Ramon Valley, and ultimately provided to DERWA.
The end user of the water would contribute financially to the Refinery Project, along with
other potential project partners, in order to keep Contra Costa Water District financially
whole. Such a large-scale project would result in greater efficiencies, align with Board
recycled water goals, lead the way on regional interagency collaboration among water
agencies, and create water supply that could be used to meet potable or irrigation
demands.
Staff will be available at the March 22, 2017, RESP Committee meeting to discuss this
request and receive direction.
Attached Suaoortina Documents:
1. DERWA Letter Dated 1127117.- Temporary Wastewater Flow Diversion Concept
2. DERWA Facilities Map
Attachment I
D A
ERW,
DSRSD*EBMUD REcycif-d Wwv? A vrhoRiry
PARnvms iv WArER 1 Ec d11vq
January 24, 2017 _1 Recelmd
Roger S. Bailey, General Manager
Central Contra Costa Sanitary District JAN 27 ZOV
5019 Imhoff place 01�A
Martinez CA 94553 �
Subject: Temporary Wastewater Flow Diversion Concept
Dear Mr. Bailey:
Earlier this month, Dan McIntyre of Dublin San Ramon Services District(DSRSD), discussed with
you the concept of diverting a portion of Central Contra Costa Sanitary District's(CCCSD)
wastewater from south San Ramon and Dougherty Valley to DSRSD to help meet peak demands of
the DSRSDEast Bay Municipal Utility District (EBMUD)Recycled Vater Authority (DERWA)
system. DER.VA is interested in exploring this opportunity with CCCSD.
DEKA.has a need for a temporary supplemental supply during the peak irrigation season to help
meet demands in the EBMUD and DSRSD service areas until wastewater flows increase with
development and other long-terra options are identified. The average daily wastewater flow from
Dougherty Valley and south San Ramon from May to 'September is approximately 2.5 million gallons
per day. DERVA would like to explore diverting,a portion of this flow from CCCSD's San Ramon
Pump Station during the irrigation season through a pilot project in partnership with CCCSD. This
wastewater diversion concept has mutual benefits to both DER. A and CCCSD including reducing
wastewater discharge, meeting peak recycled water demands, and optimizing water recycling in the
region.
To explore this potential partnership and pilot project,DER. A would like to develop a
memorandum of understanding (MOU) with CCCSD. I understand that a CCCSD/DSRSD liaison
meeting will be scheduled in late February, and will offer an opportunity to communicate at an
elected official level about a potential partnership.
I propose we schedule a meeting in early February to discuss our mutual interests and next steps.
If you have any questions or would like discuss developing the MCU, please contact me at 510-287-
01 25 or michael.tognolini@ebmud.com.
Sincerely,
Michael T. Tognolini
Authority Manager
cc: Dan McIntyre, DSRSD
V kDERWMAgreernent0upplemental Supply Agree ments'.CiCCSDOERWA Letter to CCCSD Wastewater Diversion Concept docX
701 DubliN Rou11EVARd, DubliN, CA 906&3018 0 (925) 828-056
Attachment 2
DERWA San Ramon Valley
Recycled Water Program
Current f=acilities
Location Map (April 201 6)
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