HomeMy WebLinkAboutAgenda Report - October 17, 2007 K-01K%w
AGENDA ITEM 1
4a CITY OF LODI
COUNCIL COMMUNICATION
M
AGENDA TITLE: Approve Recommendations for Preferred Site and Treatment Technology for
Lodi Surface Water Treatment Facility
MEETING DATE: October 17,2007
PREPARED BY: Public Works Director
RECOMMENDED ACTION: Approve the staff recommendation sfor the preferred site selection
and the selection of membrane treatment technology for the Lodi
Surface Water Treatment Facility.
BACKGROUND INFORMATION: At previous Council meetings, staff and the cbnsulting firm, HDR,
presented the results of a study that considered five alternative sites
for the new Surface Water Treatment Facility (SWTF) with the
objective to receive site selection direction from the City Council early
in the program. At these meetings, we also noted that among the "next steps", a presentation and request
for approval would be made in October 2007 on the preferred treatment technology.
The five alternative sites (as shown on Exhibit 1) are listed below, along with comrinents as to their
suitability:
A — The vacant 13 acres at the west side of Lodi Lake — recommended site (City{owned, lowest cost,
park/educational benefits)
B — The General Mills orchard propertywest of Site A — suitable site (similarto Site A but privately
owned, no park benefit)
C — The "scenic overlook" site at the end of Awani Drive at the Mokelumne River — not recommended
(although City -owned, significant additional cost for new River intake and fish screen and delay for
State/Federal permitting)
D — Along the Woodbridge Irrigation District (WID) Canal, 0.6 miles northwest of the corner of
Lower Sacramento Road and Sargent Road, immediately west of the proposed Westside residential
development project— not recommended (privately owned, additional pipe and land costs)
E — Along the W1 canal, just north of Turner Road — not recommended (privately owned, additional
pipe and land costs)
Council directed staff to contact General Mills regarding Site B. General Mills Site; Manager,
Carson Funderburk, has responded to the City Managerthat they have potential long-term plans for the
property and that it could be three to five years before they could determine if property was available.
Since we cannot wait that long and the Council has not indicated that it would be willing to use eminent
domain to acquire property, staff believes that Site A, the Lodi Lake property, is the best available site.
We are confident that the facility can be designed and constructed to be not only compatible with future
park uses but will actually enhance the area. Very preliminary conceptual plans and photographs will be
presented at the meeting, however, much work and future decisions will need to be made regarding the
site, including:
• Develop a master site plan for the entire parcel, including the SWTF and park uses
APPROVED:
Blair , City Manager
KIWP\PROJECTS\WATER\SuttaceWaterRFPICApproveSite, Technologydo 1011112007
Approve Recommendationsfor Preferred Site and Treatment Technology for Lodi Surface Water
Treatment Facility
October 17, 2007
Page 2
• Plan for shared facilities and improvements as much as possible to be efficient in terms of land
usage (such as roadway access, parking, restrooms)
• Attempt to minimize land needs; for example, consolidating plant elements in fewer buildings
• Design the facility with site and architectural enhancements to improve the park
' Have the SWTF facility itself provide public benefit through development of a viewing/educational
multi-purpose room, possibly as a replacementfor the aging Discovery Center currently located in
the old snack bar at Lodi Lake
Having the project literally pay the General Fund for the site is within the discretion of the Council.
Staff has assumed that the compensation and/or mitigation for park impacts would be in the form
of enhanced or additional improvements as part of the SWTF project. This does not need to be
determined at this time but should be considered in the design and financing stages.
During the discussions over the site, our consultants have completed the technology assessment for the
SWTF (attached). The recommendation is for a membrane filter system rather than "conventional"
filtration. Conventional filters use sand or other media to filter water that has chemicals added to
"flocculate" the water in order for the sand/media to remove fine material. Membranes are layers of
ceramic or other material with very small pores through which the water is pumped and very fine material
is removed from the water. The advantages of membrane systems over "conventional' include:
■ "Membranes provide a positive barrierfor the removal of all microbials and most pathogens,
which increases the flexibility of the system to meet future regulations."
• The facility footprint can be smaller and easier to expand.
■ The facility can be more automated, reducing personnel requirements.
The process requires less pretreatmentor chemical addition.
■ Costs are similar, perhaps slightly less.
"Next steps" in this project process will be to refine the site layout: complete the Watershed assessment;
and perform geotechnical work, evaluation of environmental considerations, distribution system
modification evaluation and phasinglcost estimates. The phasing and cost estimates will be used in the
financing model which is scheduled for Council presentation and direction in early 2008.
FISCAL IMPACT: Site A is the recommended site for the Surface Water Treatment Facility
and, if selected, could realize a reduced capital expenditure in excess of
$1,000,000 or provide additional public park improvements.
FUNDING AVAILABLE: Not applicable at this time
Richard C. Prima. Jr.
Public Works Director
RCPfpmf
Attachments
KIWP%PROJECTS%WATER1SurfaceWaterRFP%CAppmveSite, Technologydoc 10/1112007
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Draft Technical Memorandum
TM 5 - SWTF TREATMENT PROCESS
DESIGN DEVELOPMENT
City of Lodi Surface Water Treatment
Facility Conceptual Design and Feasibility
Evaluation October 10, 2007
Reviewed by: Richard Stratton, P.E.
Prepared by: Shugen Pan, PhD, P.E.
Introduction
The proposed Surface Water Treatment Facility (SWTF) project will treat surface water from
the Mokelumne River to supplement the City's existing groundwater supply. Treatment
technologies available for the SWTF include either a conventional process consisting of
coagulation, flocculation, sedimentation, dual media (anthracite/sand) filtration; or a membrane
treatment process utilizing microfiltration or ultrafiltration membranes. The purpose of this
technical memorandum (TM) is to establish design criteria for both conventional and
membrane treatment processes at the proposed SWTF, evaluate the advantages and
disadvantages of each process, and recommend the best treatment process. The process
schematic, preliminary site plan showing the layout and required footprint, improvements
needed to provide access to the site, hydraulic profile, and preliminary floor plans for key
buildings will be presented for the recommended process.
Additional elements of the project that are covered in other TMs include:
TM 2 - Alternative Site Selection — Initial Screening
TM 3 - Watershed Assessment
TM 4 - Regulatory Review
TM 6 - Surface Water and Groundwater Blending
These TMs will develop information that may modify the final design criteria of the
recommended treatment process. However, the comparison evaluation of the processes
will not be affected by these changes. For example, TM 6 may recommend addition of
polyphosphates to stabilize corrosion scales in the existing piping after introduction of
surface water. This would be required for either a conventional or a membrane process
and would not change the decision on which alternative is preferred.
City of Lodi
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Draft Technical Memorandum
Basic Design Criteria for Both Conventional and Membrane
Treatment Alternatives
The basic design criteria for a water treatment plant are established to address raw water quality
challenges, to comply with current and future regulations, and to reliably operate to meet the
anticipated range of water demands. The basic design criteria common to both conventional
and membrane treatment alternatives can be divided into three groups: raw water quality,
treatment capacity/reliability, and treated water quality/regulatory compliance.
Raw water quality
The proposed City of Lodi SWTF will treat water from the Mokelumne River through the
Woodbridge Irrigation District (WID) irrigation canal intake and fish screen. The water quality
is evaluated in detail in the future watershed assessment TM and is briefly summarized in Table
1.
It should be noted that data represent the general quality of the water at the sampling sites.
Additional sampling has been performed by City Storm Water trackers during the winter
season. This data has shown that the raw water turbidity could be greater than 50 NTU during a
storm event.
Overall, the Mokelumne River is an excellent water source that has low total dissolved solids
(TDS) and total organic carbon (TOC) concentrations. The levels of total coliform and Giardia
Cysts are slightly elevated, but these can be effectively removed by membranes or the
combination of conventional filtration followed by ultraviolet disinfection.
City of Lodi 2
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Draft Technical Memorandum
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Table 1
Water Quality Data from Mokelumne River and WID Canal Sampling Sites, May 2006 -July 2007
Site 1:
Mokelumne River'
Site 2: WID Canal Near River.Z.
Site 3: WID Canal Past Rale s3.
Site 4: Woodbrid a Dam .°.
Constituent Max.
Min.
Mean
Max.
Min.
Mean
Max.
Min.
Mean
Max.
Min.
Mean
H, SU 8.6
6.2
7.4
7.8
6.3
7.1
7.8
6.3
7.1
8.8
7.7
8.0
Total dissolved solids, mg/L 45
25
31
42
25
32
43
22
31
45
24
35
Specific conductance, µS/cm 52
32
40
48
31
39
52
32
39
44
35
39
Turbidity, NTU 5.7
1.3
2.6
4.3
1.0
2.5
3.5
1.1
1.9
3.4
1.4
2.4
Alkalinity, m 23
1 15
<20
21
<20
1 6
22 1
16
10
<20
<20
<20
Hardness, mg/L 16
13
14
15
13
14
16
13
14
14
13
14
Calcium, m 4
3.4
3.6
4.0
3.5
3.7
4.1
3.5
3.7
3.7
3.5
3.6
Iron, mg/L 0.20
<0.10
0.15
0.17
<0.10
0.13
0.12
<0.10
<0.10
0.23
0.12
0.16
Magnesium, mg/L 1.3
1.0
1.2
1.3
1.1
1.2
1.3
1.1
1.2
1.2
1.1
1.2
Copper, 5.8
<5.0
<5.0
<5.0
<5.0
<5.0
<5.0
<5.0
<5.0
<5.0
<5.0
<5.0
Zinc, /L 27.0
1 <5.0
9.6
31.0
<5.0
1 10.2
32.0
<5.0
13.2
8.1
<5.0
<5.0
Total organic carbon, mg/L 2.7
1.1
1.5
2.9
<1.0
1.7
2.8
1.1
1.6
1.6
1.2
1.4
Dissolved organic carbon, mg/L 2.4
<1.0
1.0
2.5
1.1
1.5
2.5
<1.0
1.3
1.5
1.1
1.3
Total coliform, MPN/100mL 1600
60
509
>1600
240
1019
>1600
300
1030
1600
170
766
Fecal coliform, MPN/100mL 140
13
69
170
13
59
900
30
330
140
23
75
Giardia, cysts/mL 9.5
<0.5
2.0
4.0
<0.5
1.0
4.5
<1.0
2.1
4.0
<0.5
<0.5
Cryptosporidium, ooc sts/L <0.10
1 <0.05
<0.05
0.05
<0.05
1 <0.05
<0.1
<0.05
<0.05
<0.1
<0.05
<0.05
VOCs, µg/L ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
SOCs,µ ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
Source: City of Lodi Public Works Department, 2007
.1. Mokelumne River shore on north side of Vaccarreza property (1300 block E. Turner Road); 15 samples from May 3, 2006 through July 18, 2007
2. WID Canal from bridge over canal on Orange Street; 10 samples from May 3 through October 11, 2006 and April 4 through July 18, 2007
3. WID Canal past Raleys from bridge on Lower Sacramento Road by well 13; 10 samples from May 3 through October 11, 2006 and April 4 through July 18, 2007
4. Just upstream from Woodbridge Dam; 5 samples from November 29, 2006 through March 7, 2007
Key: µg/L = micrograms per liter
mg/L = milligrams per liter
MPN/ 100mL = most probable number per 100 milliliters
ND = not detected
NR = not reported
NTU = nephelometric turbidity unit
µS/cm = microSiemens per centimeter
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Treatment capacity/reliability
Draft Technical Memorandum
The City currently uses groundwater as its sole source of supply. A total of 26 groundwater
wells located throughout the City's distribution system provide a combined capacity of 3 5,2 10
gallons per minute (gpm) or 50.7 million gallons per day (mgd) based on the City's 2005 Urban
Water Management Plan (UWMP). The City has historically used from 11,462 AFY of
groundwater in 1970 to 17,108 AFY in 2001. Historical data indicate that the City's
groundwater elevation decreased on average 0.39 feet per year from 1927 to 2004, although
groundwater elevation also fluctuates due to annual rainfall. Historical groundwater elevation
and annual rainfall are presented in Figure 1.
Figure 1. Historical groundwater elevation and annual rainfall
This figure indicates that the groundwater basin underlying Eastern San Joaquin County that
supplies the City's wells is in an overdraft condition. The 2005 UWMP estimates that the safe
yield of the underling groundwater basin is approximately 15,000 AFY on an acreage -based
relationship although more rigorous scientific analysis could be done to confirm the safe yield.
The declining groundwater basin is a result of groundwater extraction by all groundwater users
in the area, including other cities, agriculture, private well owners, and the City. The City plans
to reduce its groundwater pumping in the long term as part of a regional effort to stabilize the
groundwater basin.
City of Lodi 4
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Figure 1. Historical groundwater elevation and annual rainfall
This figure indicates that the groundwater basin underlying Eastern San Joaquin County that
supplies the City's wells is in an overdraft condition. The 2005 UWMP estimates that the safe
yield of the underling groundwater basin is approximately 15,000 AFY on an acreage -based
relationship although more rigorous scientific analysis could be done to confirm the safe yield.
The declining groundwater basin is a result of groundwater extraction by all groundwater users
in the area, including other cities, agriculture, private well owners, and the City. The City plans
to reduce its groundwater pumping in the long term as part of a regional effort to stabilize the
groundwater basin.
City of Lodi 4
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Water demand
Draft Technical Memorandum
The 2005 UWMP reports that City's average annual water demand for the period 1995 to 2004
was 14.94 mgd. The maximum day peaking factor (the maximum demand divided by the
average annual demand) for the City's water demand ranged from 1.80 to 2.30 with an average
of 1.91 The maximum month demand typically occurs in either August or July with a peaking
factor of 1.7. The monthly demand during the year based on 2005 and 2006 demand data is
presented in Table 2
Table 2. Monthly Demand Data
Month
Average Monthly
Demand, m d
Peaking Factor - (Monthly
Demand/Annual Average Demand
January
7.6
0.52
February
7.9
0.54
March
8.1
0.56
April
9.9
0.68
May
16.5
1.13
June
21.3
1.46
July
24.8
1.70
August
23.8
1.63
September
20.2
1.39
October
15.7
1.08
November
11.0
0.75
December
8.2
0.56
Annual Average
14.58
MGD
Based on the historical peaking factor and the projected water demand, the year is divided into
3 seasonal demand groups: summer, spring -fall, and winter. Projected potable water demands
for each are season presented in Table 2. These values assume water conservation practices will
be implemented as described in the UWMP.
Table 3. City of Lodi Current and Projected Total Water Demand (Ref. 2005 UWMP)
Demand Criteria
Units
2005
2010
2015
2020
2025
2030
Annual demand
AFY
17,300
17,900
18,400
19,100
19,800
21,300
Average Annual Daily Demand
MGD
15.4
16.0
16.4
17.1
17.7
19.0
Summer (June -September) Average
Daily Demand*
MGD
24.6
25.6
26.2
27.4
28.3
30.4
Spring -Fall (April, May, October,
November) Average Daily Demand *
MGD
15.4
16
16.4
17.1
17.7
19
Winter (December -March) Average
Daily Demand *
MGD
9.2
9.6
9.8
10.3
10.6
11.4
*Summer (1.6 x annual average); Spring -Fall (1.0 x annual average); Winter (0.6 x annual average)
Water supply
Based on the UWMP, the projected potential potable water supply for the City includes 15,000
AFY of groundwater and 6,000 AFY of WID surface water. The projected 15,000 AFY of
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groundwater is based on the estimated safe yield, however, this estimate is not guaranteed. The
actual safe yield could be less than projected, and it will depend on the cooperation of all other
groundwater users to be sustainable. Recycled water usage is covered in TM 11 - Phased
Capacity Analysis. Demands associated with current reclaimed water usage at the White
Slough Facility are not included in the demands listed in Table 3. Although the recycled water
could be a reliable source to offset some potable water usage, the water quality is not as good as
potable water and the public may be reluctant to accept is as a supplemental source for current
potable water uses.
To increase the flexibility and reliability of the City's water supply, the City is actively
exploring possibilities with the WID and East Bay Municipal Utility District (EBMUD) to use
more of the Mokelumne river water. It is expected that up to 6,000 AFY additional surface
water could be acquired. Considering both the contracted surface water and the additional
surface water available pending negotiation, the total available surface water could be as much
as 12,000 AFY. This is equivalent to 10.7 million gallons per day (mgd) assuming year-round
operation, or 17 mgd if water usage is limited to March 1 through October 15.
The current groundwater supply is provided by 26 wells with capacities ranging from 1.2 to 3.0
mgd. When determining the maximum surface water usage possible during the winter,
consideration must be given to the fact that the wells must be operated on a maximum 3 -day
rotation to ensure well good performance. This means that 8 wells must be operated every day
for at least 6 hours (2 wells running at all times). Assuming an average well capacity of 2 mgd,
the most surface water that can be used during the winter months on an average in 2030 would
be 6.5 mgd.
Treatment capacity
The capacity of the SWTF should be sufficient to treat the contracted surface water, banked
water, and future surface water supplies. The required capacity of the SWTF is dependent on
whether it is operated year round or only during the irrigation season (from March 1 st to
October 15th.). Higher capacity is needed if the facility is operated during the irrigation season
only. The SWTF should be designed to treat the maximum amount water available during the
year and allow operation at maximum capacity during the summer high demand months and at
lower capacity during the winter so that the groundwater wells can be exercised sufficiently.
The SWTF should also be designed with sufficient reliability. Key unit processes in the
treatment train will utilize the N+1 approach, i.e., capacity will be based on one unit off-line.
The required treatment capacities of the SWTF by season for utilizing the maximum water
supply from the Mokelumne River for the year 2030 demands are summarized in Table 4. The
required capacities are shown for both year round operation and for operation only during the
irrigation season.
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Table 4. Required Treatment Capacities of the SWTF based on Year 2030 Demands
Demand Criteria
Summer
Spring and
Fall
Winter
Year Round Operation
Maximum Day
16 mgd
14 mgd
7 mgd
Minimum Day
12 mgd
10 mgd
5 mgd
Average Day
14 mgd
12 mgd
6 mgd
March 1 through October 15 Operation
Maximum Day
26 mgd
14 mgd
7 mgd
Minimum Day
20 mgd
10 mgd
5 mgd
Average Day
23 mgd
12 mgd
6 mgd
The design capacity required to fully utilize the 12,000 AFY of water contracts for year round
operation is 16 mgd. If operation is limited to the irrigation system, a plant capacity of 26 mgd
would be required.
For the initial phase (year 20 10) of the project, it is assumed that that 3,000 AFY of banked
water would be used along with the 6,000 AFY contract amount. The required treatment plant
capacities by season for the initial phase are shown in Table 5.
Table 5. Required Treatment Capacities of the SWTF based on Initial Phase
Demands Using Banked Water
Demand Criteria
Summer
Spring and
Fall
Winter
Year Round Operation
Maximum Day
12 mgd
10 mgd
7 mgd
Minimum Day
8 mgd
6 mgd
5 mgd
Average Day
10 mgd
8 mgd
6 mgd
March 1 through October 15 Operation
Maximum Day
18 mgd
12 mgd
7 mgd
Minimum Day
13 mgd
8 mgd
5 mgd
Average Day
16 mgd
10 mgd
6 mgd
Based on the initial demands including use of banked water, it is recommended that the City
construct the SWTF in two phases. The first phase shall have a summer capacity of 12 mgd and
leave room for a second phase expansion of 4 to 6 mgd. The size of the first phase and second
phase expansion will depend on the actual amount of future water supply and whether or not
the plant operates year round. The following sections are based on an initial firm treatment
plant capacity of 12 mgd.
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Treated water quality / Regulatory compliance
Draft Technical Memorandum
The treated water quality goals for the SWTF are based on an assessment of regulatory
requirements (both existing and future), maximum contaminant level (MCLS), required
treatment techniques (TT), secondary standards, required pathogen log removals, and aesthetic
water quality goals. Pathogen log removal is based on taking the converting the logarithm of
(1- minus the percent removal (as a fraction) to a positive number. For example, 99.9 percent
removal is equal to a 3 -log removal [-log(1-0.999)]. The water quality goals for this project are
summarized in Table 6.
Table 6 —Treated Water Quality Goals
Contaminant/Parameter
Treated Water
Goal
MCL or TT
Secondary Standard
Arsenic (mg/L
<0.008
0.010
Fluoride (mg/L
< 2.0
4.0
2.0
Nitrate as N (mg/L
<8.0
10
Nitrite as N (mg/L
<0.8
1
Gross Alpha Ci/L
<10
15
Uranium (ug/L
<10
30
Total Trihalomethanes (TTHM) (ug/L
as LRAA
<64
80
Haloacetic Acids (HAA) (ug/L as
LRAA
<48
60
Turbidity NTU
<0.3
TT. .
Aluminum (mg/L
<0.05
0.05 to 0.2
Chloride (mg/L
<100
250
Color color units
<5
15
Copper (mg/L
<0.8
1.0
Iron (mg/L
<0.3
0.3
Manganese (mg/L
<0.05
0.05
Odor TON
<3
3
H
7.5-8.3
6.5-8.5
Sulfate (mg/L
<100
250
Total Dissolved Solids (mg/L
<300
500
Zinc (mg/L
<5
5
Cryptosporidium
4 log
removal/inactivation
TT. .
Giardia lamblia
4 log
removal/inactivation
TT12)
Viruses
4 log
removal/inactivation
TT12)
TT: Treatment Technique
(1) Combined filter effluent turbidity <0.3 NTU in 95% of measurements taken each month. The maximum
turbidity is 1 NTU.
(2) Minimum 3 -log removal/inactivation of Giardia (99.9%); minimum 4 -log removal/ inactivation of viruses
(99.99%); and minimum 3 -log to 5.5 -log removal/inactivation of Cryptosporidium depending on the source
water quality.
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Draft Technical Memorandum
Review of Appropriate Treatment Technologies
The typical water treatment process train includes three basic unit operations: pretreatment,
filtration, and disinfection. In addition to the basic unit operations, other treatment units or
chemicals are often included to optimize water treatment and achieve better treated water
quality. These treatment units include grit removal, oxidation chemicals, powdered activated
carbon (PAC) and corrosion inhibitors. For some waters advanced treatment such as granular
activated carbon (GAC) and nanofiltration or reverse osmosis (NF/RO) are included in the
process. The treatment processes that would be appropriate for treating raw water from the
Mokelumne River via the new WID intake are summarized in Table 7.
Table 7. Appropriate Treatment Processes for Mokelumne River Water Supply
Treatment Category
Appropriate
Unit Processes
Pretreatment
•
Conventional Coagulation/Sedimentation
•
Coagulation for Direct Filtration
•
Dissolved Air Flotation
•
Sludge Blanket Clarifiers
•
Ballasted Clarification
•
Plate or Tube Settlers
Filtration
•
Conventional Dual Medial Filters
•
Microfiltration or Ultrafiltration Membrane Filtration
Disinfection
•
UV
•
Chlorine
•
Chloramines
•
Ozone
Oxidation
•
Ozone
•
Chlorine Dioxide
•
Chlorine
•
Chloramines
•
Potassium Permanganate
•
Hydro en Peroxide
Other Chemicals
•
Powdered Activated Carbon (PAC)
•
NaOH
•
Corrosion Inhibitors
Alternative Advanced Processes*
•
GAC
•
Nanofiltration or Reverse Osmosis
*These processes are for enhanced Total Organic Carbon (TOC) and /or Total Dissolved Solids (TDS)
removal and are not necessary for this project.
Theoretically, there are forty-eight possible treatment trains based on the pretreatment,
filtration, and disinfection alternatives listed in the above table. If oxidation and advanced
treatment are included in the consideration, the possible trains are much more. To simplify the
evaluation process, only the most feasible treatment processes, based on a review of industry
experience with these unit processes, are selected for evaluation. First, two filtration
technologies (i.e. conventional dual media filtration and membrane filtration) are selected as
the base unit of each treatment trains. The full treatment trains are developed by expanding the
base unit with the addition of pretreatment and disinfection technologies that are most feasible
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when combined with the base unit, considering raw water quality, treated water quality goals,
existing and future regulations, and engineering judgment. The following sections will review
appropriate treatment processes for treating Mokelumne River water (including pretreatment,
filtration, and disinfection) technologies and determine their suitability to the proposed SWTF.
Pretreatment Alternatives
Conventional sedimentation involves chemical addition, rapid mixing, coagulation,
flocculation, and sedimentation. This process has been demonstrated to be capable of removing
turbidity, color, TOC, Dissolved Organic Carbon (DOC), viruses, bacteria, and protozoans such
as Giardia and Cryptosporidium. This pretreatment alternative can cope with source water
turbidity up to 1,000 NTU or higher and is a reliable pretreatment alternative for both
membrane and conventional filters.
Conventional flocculation and sedimentation basin (Yuba City)
Coagulation and Flocculation for Low Turbidity Wa m
If the raw water source has low turbidity such as found in lakes, reservoirs or rivers flowing out
of lakes/reservoirs, pretreatment consisting of coagulation followed by flocculation may
provide sufficient pretreatment prior to filtration. This approach is often called direct filtration.
Since sedimentation basins are not required, costs are lower for direct filtration plants than for
conventional plants. Coagulation followed by direct filtration with media filters generally
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requires that the average raw water turbidity is less than 10 NTU and thus will not be feasible
for dual media filtration at the proposed SWTF if year round operation is desired. In addition,
DHS regulations provide a lower Giardia log removal credit of 2.0 for direct filtration which
would necessitate a more robust disinfection system to achieve the 3.0 log total log removal
requirement. In many cases, if there is a concern with elevated levels of bacteria or cysts in the
water supply, the Department of Public Health will require full conventional treatment and not
allow direct filtration.
On the other hand, coagulation followed by membrane filtration has been frequently used to
treat surface water with inlet turbidity as high as 100 NTU for short durations. An example is
the Yucaipa Valley Water District membrane WTP that treats water from California Aqueduct
via Lake Silverwood and the Crafton Hills Reservoir without pretreatment. Given the
comparable quality of the Mokelumne River to the water leaving Lake Silverwood, it is
expected that coagulation with direct membrane filtration will do well at the proposed SWTF.
Dissolved Air Floatation
Dissolved air floatation (DAF) is based on the principle that the naturally occurring and
coagulated particles can be made to float with the help of dissolved air bubbles. The
flocculation time used in DAF plants are typically less than those used by conventional
coagulation sedimentation plant. Advantages of DAF include:
➢ Small tanks compared with those for sedimentation
➢ Possibly lower coagulant and flocculent aid dosages, can operate without
polymer addition
➢ Provide better removal of low density particles and algae
➢ Greater sludge solids concentration.
DAF is a suitable pretreatment for both media filter and membrane filters for the proposed
SWTF.
Schematic of DAF
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Sludge Blanket Clarifiers
Draft Technical Memorandum
Sludge blanket clarification, or solids contact clarification, involves coagulation within a mass
of previously formed solids. Coagulation chemicals are added in a rapid mixing chamber and
the water and resulting particles then percolate upward through a sludge blanket. The contact
between the newly flocculated particles and the existing mass in the sludge blanket aids in the
removal of particles from the water because newly formed particles readily adsorb onto existing
particles. During stable operation, the sludge blanket clarifier can generally produce lower
turbidity water compared with the conventional sedimentation basin. One disadvantage of the
sludge blanket clarifiers is the blanket stability can be disrupted during flow changes, abrupt
water quality changes, or temperature changes, resulting floc carryover to the filters. Sludge
blanket clarification is a viable pretreatment for both media and membrane filtration.
Ballasted Clarification
Ballasted clarification is a high -rate clarification system (e.g., Actiflo by Kruger), which
includes separate chemical addition, followed by rapid mixing, flocculation, and sedimentation
compartments within a single unit. The process utilizes microsand to enhance flocculation and
settling. Settleable particles adhere to the microsand and are removed in the sedimentation
compartment. The settled solids/microsand is pumped to a hydrocyclone where the microsand
is separated and returned to or reused in the flocculation compartment. The solids/sludge is
discharged to the solids handling process.
The advantages of ballasted processes are the reduced coagulation and flocculation times and
the higher rise rate compared to conventional settling. The ballasted flocculation process has
been successful even under extreme conditions such as low temperature, high color, and very
high or very low turbidities. Ballasted flocculation is expected to perform well as the
pretreatment alternative for media filters. Ballasted clarification has also been used ahead of
membrane filters, however, testing at many facilities indicates that polymer carryover can occur
causing rapid fouling of the membranes. Ballasted clarification would not be the best fit for the
proposed SWTF if membranes are selected.
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Schematic of ACTIFLO and ACTIFLO Facility (City of Fresno)
Plate and Tobe Settlers
Draft Technical Memorandum
Plate and tube settlers are very similar in nature and only plate settler will be discussed here.
Plate settlers perform the same function as conventional sedimentation basins and can be
installed in the same location in the process train. Flocculated water enters the plate settler at
the bottom of the plates and flows through the inlet channel to each plate. Water enters the
settling area between the inclined plates through openings on both sides of the plates, and flows
upward between the plates to the outlet area. Settled solids slide down the inclined surface and
drop into the basin below.
Plate settlers allow for overall basin loadings from 2 to 4 gpm/ft2., several times that for
conventional basins, thus offering considerable savings in space and cost for sedimentation.
Plate setters are expected to perform well as the pretreatment for both media filter and
membrane filter for the proposed SWTF.
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Draft Technical Memorandum
Stainless Plate Settler installed in Sedimentation Basin (Kennewick, WA)
Filtration Alternatives
Filtration is the heart of surface water treatment plants and is needed for most surface waters in
order to provide a barrier against the transmission of waterborne diseases. Filtration and
disinfection together provide an effective barrier against pathogens. Filtration can assist
significantly by reducing the load on the disinfection process and increasing disinfection
efficiency. Filtration can be divided into two basic types: media filtration and membrane
filtration. Each type of filtration will be briefly discussed in the following sections.
Media Filtration
Media filtration can include slow sand filtration (0.05 to 0.1 gpm/ft2.), rapid sand filtration (1 to
2 gpm/ft2), high -rate granular media filtration (up to 10 gpm/ft2, or even higher), Diatomaceous
Earth (DE) filtration, and those used in pressure filters such as green sand filtration. High -rate
granular media filtration is the most commonly used media filtration in modern surface water
treatment plants and will be the basis of this evaluation. Media configuration in the high -rate
granular media filter can be 1) conventional sand; 2) dual -media (coal over sand); 3) mixed
media (coal over sand over garnet); and 4) deep bed (coarse sand or coal, unstratified, 48 to 72
inches). Granular activated carbon (GAC) caps, a layer of GAC on top of the filter media, has
also been frequently used to improve filtration and organic removal.
Effective operation of a media filtration system requires effective pretreatment of the source
water. The nature, as well as the quantity, of suspended material in the pretreated water can
greatly influence filter performance. The most commonly used filtration pretreatment process is
coagulation/flocculation and sedimentation. Unflocculated water can be difficult to filter
regardless of the type of medium used.
With proper pretreatment, media filters typically can operate from 12 to 96 hours before either
reaching the head loss limit or experiencing a turbidity breakthrough leading to poor effluent
water quality. A filter backwash is required when either of the above condition occurs. Media
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filters are typically backwashed with finished water at 15 to 20 gpm/sf with the bed expansion
being between 15 and 30 percent. Backwash cycles are generally 10 to 20 minutes in duration.
Air scour is generally used during backwash to enhance the cleaning of the filter media.
Dual media filters (GAC over sand) rated for operation up to 9 gpm/sf (West Sacramento)
At the end of a backwash cycle, some particles remain trapped within the filter bed. When a
filter is returned to service after backwashing, these particles are carried into the filter effluent,
causing elevated turbidities and particle counts during the initial filtration period. A "filter -to -
waste" step is generally required before a filter is put back in to normal filtration after a
backwash. The filtered water collected during this period is recycled to an upstream location in
the process stream or delivered to a separate treatment process.
11-i-N"F7: ra =
There are four types of pressure membrane systems that are typically used in water treatment.
These are Microfiltration (MF), Ultrafiltration (UF), Nanofiltration (NF), and Reverse Osmosis
(RO). Microfiltration is a low-pressure membrane process with the largest pore size
membranes. Microfiltration can easily remove Giardia lamblia cysts and Cryptosporidium
oocysts as well as other microorganisms, colloids, and high -molecular weight compounds.
Ultrafiltration is another low-pressure membrane system that operates at a slightly higher
pressure and has smaller pore size than MF. Since the membrane pore size is smaller, it can
remove what MF can remove plus viruses. Nanofiltration operates at a much higher pressure
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than either MF or UF, but less than RO. NF is capable of removing hardness, pathogens,
viruses, some dissolved organics, and organic color. RO is the membrane system with the
smallest membrane pores and operates at the highest pressures. It is capable of removing most
organic compounds and ions, all bacteria, viruses, microorganisms, and radionuclides. For this
project, MF and OF are the membrane systems that can replace conventional surface water
treatment systems at a comparable cost.
Microfiltration and ultrafiltration are hollow -fiber membrane systems that remove contaminants
by physical straining (sieving). The membranes remove particulates by physically straining
from the water the particles greater than the nominal pore size of the membrane. The OF
membranes pore size (0.01 micron) is about one order of magnitude less than the MF pore size
(0.1 micron). These membrane systems can be pressure -driven or vacuum -driven membrane
processes that operate at low (5 to 50 psi) pressures and flux rates of 15 to 75 gallons/ft2./day
(gfd). Chemical conditioning of the raw -water feed is usually not required except where
enhanced organics or pathogen removal is desired. Due to the projected organic levels in the
raw water, a chemical coagulant will be needed to reduce dissolved organic carbon (DOC) and
Disinfection Byproduct (DBP) in the finished water.
While the MF and OF systems are pressure driven, there are two basic configurations —
modules mounted in pressure vessels operating under positive pressure and modules submerged
in an open basin that operate under vacuum. For the positive pressure system, the water is
pumped through the membranes. For the vacuum system, the membrane is submerged in a
metal or concrete tank and the water is pulled through the membrane by a pump. The
submerged systems operate at a lower transmembrane pressure than do pressure systems.
Most membranes used in municipal water treatment are prepared from synthetic organic
polymers. These membranes include those supplied by USFilter/Memcor, Zenon, Pall, Koch,
and Norit. Inorganic membranes are available, such as the NGK ceramic membranes supplied
by Kruger. Although the ceramic membrane is more expensive than the other MF and OF
membranes, it does offer the following advantages: High flux rates (greater than 100 gfd);
direct filtration of high turbidity water; long membrane life; high water recovery; minimized
Clean -in -Place (CIP) requirements. CIP involves soaking the membranes in caustic and acid
solutions to remove accumulated contaminants not removed by the normal backwash process.
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Draft Technical Memorandum
NGK Ceramic Membrane Installation (Japan)
The general operation of the membrane types discussed above is basically the same.
Particulates, microorganisms, and colloidals are filtered from the water by the membrane. As
more and more material is removed from the water, the operating pressure increases, so
periodically the system is backwashed to remove the filtrate and return it back to original
operating conditions. In addition to the normal backwashing, membranes need to be
periodically cleaned chemically to remove any scale or particulate matter that is not removed
with normal backwash. Some systems use a daily maintenance wash in which sodium
hypochlorite is used. In addition to the maintenance wash, a "clean -in-place" (CIP) is used
about every month to remove the accumulated organic and inorganic scales. Normally citric
acid, caustic and a surfactant are used to soak the membranes during the CIP operation.
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Picture of two Memcor submerged membrane systems (Yuba city, CA- upper left, and Bendigo,
Australia- lower left), a Zenon 1000 membrane cassette module (South San Joaquin Irrigation
District -upper right), and a Pall pressure membrane system (Yucaipa Valley Water District- lower
right)
Disinfection Alternatives
Disinfection usually is the last step of a treatment process and provides the final barrier against
pathogens prior to pumping to the distribution system. Types of disinfection presented in this
section include ultraviolet light, chlorine, chloramines, and ozone. EPA and California
Department of Public Health regulations require a certain combined log removal/disinfection
pathogens based on the raw water quality. Conventional treatment with
flocculation/sedimentation/filtration is given a maximum of 2.5 log removal credit of Giardia
and 3 -log removal credit of Cryptosporidium. Based on the raw water quality, a conventional
surface water treatment plant may be required to provide an additional 2.5 log
removal/disinfection for Cryptosporidium.
Membrane filters provide an absolute barrier against pathogens such as Giardia,
Cryptosporidium and are approved by the California Department of Health Services (CDHS)
for minimum four logs removal of Giardia and Cryptosporidium. With the use of membrane
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filtration, only limited disinfection is needed primarily to provide a multi -barrier approach
against pathogens and to provide a chlorine residual in the distribution system. The water is
disinfected using UV disinfection, Chlorine, Chloramines or Ozone which are presented in the
following paragraphs
Disinfection with W
Ultraviolet (UV) light disinfection can be used as an effective barrier for the inactivation of
many waterborne pathogens. UV light wavelengths range from 200 nm to 400 nm, the
germicidal range is between 230 and 260 nm. Major components of UV systems include a
chamber, UV lamps, quartz sleeves, cleaning system, ballasts, and a control system. The UV
lamps are housed in quartz sleeves for protection from encrustation and breakage. There are
three types of UV lamps used for disinfection: low pressure, low pressure/high intensity, and
medium pressure. Low pressure lamps (both low pressure and low pressure high intensity)
produce a monochromatic wave that is primarily in the germicidal range. Medium pressure
systems are polychromatic, producing wavelengths over the entire UV range.
The cleaning systems are necessary to keep the quartz sleeves clean so that the UV can be
transmitted into the water. Cleaning frequency, as well as the type of chemicals used, depends
on the water quality. Both chemical/mechanical and mechanical self-cleaning systems are
available on low pressure/high intensity or medium pressure systems. Low pressure systems
generally require manual cleaning.
Transmittance is the ability of UV light to travel through water. For example, high turbidity
water will have a low transmittance. Waters with low transmittance will require a greater
dosage of UV to achieve adequate disinfection; therefore, UV is not typically applied to high
turbidity, low transmittance waters. UV irradiation would need to be applied to filtered water.
UV disinfection does not leave any residual in the finished water. Therefore, if UV is used as
the primary disinfection, a chemical disinfectant (such as chlorine or chloramines) will still be
needed to protect water in the distribution system as required by regulation. Chloramines are
not required for low TOC waters such as found in the proposed Mokelumne River water supply
and will therefore be eliminated from further consideration.
The advantage of UV disinfection compared with using chlorine is that UV disinfection does
not produce known disinfection by products (DBPs) and UV is proven to inactivate
Cryptosporidium oocysts. Because a chlorine residual is required for water leaving a surface
water treatment plant, the lack of DBP formation by UV is of little value since DBPs could be
formed in the distribution system. However, since chlorine is not effective in Cryptosporidium
oocysts inactivation, UV disinfection may be necessary to comply with the regulatory
requirements for pathogen removal at the proposed SWTF, if media filtration is selected. For
source waters with low TOC such as the Mokelumne River, UV disinfection is normally not
used after membrane filtration because membranes are able to remove both Cryptosporidium
oocysts and Giardia cysts.
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Chlorine
Draft Technical Memorandum
Chlorine in the form of chlorine gas or sodium hypochlorite has been the most widely used
chemical for drinking water disinfection. Chlorine is a relatively inexpensive disinfectant, and
it has been very effective for the inactivation of many kinds of microorganisms. This has
contributed to its widespread usage.
Free chlorine has some limitations that can be handled in the design:
First, its effectiveness is pH dependent. At pH values above 7, hypochlorous acid
(HOCI), the more powerful form of free chlorine, disassociates to form hypochlorite ion,
OCl-, a weaker disinfectant. Thus, as the pH increases above pH 7, free chlorine
disinfection is less effective. To address this issue, the clearwell will be baffled and sized
to provide the needed contact time.
Second, using free chlorine as a disinfectant forms DBPs such as trihalomethane (THM)
and haloacetic acid (HAA) if TOC levels are high. The average TOC level in the raw
water is less than 2.0 mg/L which minimizes the concern for DBPs. Coagulant can be fed
to reduce TOC levels, if needed.
Third, chlorine is not an effective disinfectant for Cryptosporidium. UV disinfection or
membranes can be utilized to inactivate or remove Cryptosporidium.
Chlorine has been used effectively as a disinfectant for many years by many utilities. The use
of free chlorine at the proposed SWTF as the primary disinfectant and to provide a chlorine
residual in the distribution system will be a viable following membrane filtration. For
conventional treatment, UV disinfection may be requited as the primary disinfectant with
chlorine used for the distribution system residual.
Chloramines
Chloramines have become more widely used due to their ability to provide disinfection without
substantial THM formation. Taste and odor control and maintenance of a more stable residual
in distribution systems are other benefits of chloramine usage. If improperly managed,
however, the application of chloramines can support bacterial growth in the distribution system
as well as cause nitrification problems. Another drawback of chloramines is that if used, kidney
dialysis patients and people with fish tanks must be informed to remove the chloramines or risk
of damage to dialysis equipment or killing of fish.
Chloramination is accomplished by combining free chlorine with ammonia or an ammonium
salt, to form chloramine. Chloramine is not as strong as chlorine for disinfection, and it is not
recommended as a primary disinfectant by the USEPA. Chloramine does, however, form a
persistent disinfectant residual, and is used by numerous water utilities for maintenance of a
residual in the distribution system. Chloramine is slower to react with substances on the walls
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of water mains, thus it has a better opportunity to penetrate tubercles and biofilms and kill
resident bacteria.
Chloramination would not be suitable as the only disinfectant, but chloramines are effective
secondary disinfectants for maintenance of a residual in the distribution system.
Chloramination is not considered a viable secondary disinfectant for the proposed SWTF. It
should only be considered if TOC levels become higher and DBP formation becomes a
concern.
Ozone is more effective than other chemical disinfectants against Cryptosporidium. Ozone
must be generated on site and it dissipates rapidly in water so that a residual can not be
maintained with ozone. Ozone also breaks down organics in water into smaller molecules that
are more easily used by microorganisms. These organic molecules must be removed with a
biological active filter to minimize biological growth in the distribution system. In water
treatment applications ozone is used more frequently as an oxidant for taste and odor control
than as a disinfectant. Given its high expense, ozone is not justified for treating water from the
Mokelumne River.
Alternatives for Ancillary Treatment
In addition to the three basic treatment categories discussed above: pretreatment, filtration, and
disinfection; many other ancillary treatment units and/or chemicals are needed to achieve the
treatment goals such as providing taste and odor removal and corrosion control. The ancillary
treatment units and chemicals appropriate to membrane filtration and conventional filtration are
incorporated into the two treatment alternatives discussed in the following sections.
Conventional Treatment Alternative
Schematic
A schematic of the conventional treatment process train for the City of Lodi SWTF is presented
in Figure 2. The schematic shows onsite solids handling with disposal to a landfill. If
determined to be cost-effective, the solids from the plate settler could be discharged directly to
the sewer for processing at the City's White Slough Water Pollution Control Facility.
Design Criteria
The design criteria of the conventional treatment system are summarized in Table 8.
City of Lodi 2
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MOKELUMNE
RIVER
FISH
SCREEN
TO BWW
HOLDING BASIN
48"
1 NTAKE
REC
LOW LI FT
PS
GRIT
REMOVAL
ALUM, POLM,
NaOH PAC C12
SEDIMENTATION FILTER
BASIN DUAL
C12 MEDIA H202 NaHS03
HIGH
FLASH FLOCULATION UV CLEARWELL SERVICE
PUMPING
MIX BASIN
HOLDING BWW
BASIN
C0 NAL TREATMENT
SCALE: NONE
NON—POTABLE
HOLDING TANK
:AD
TO
LANDFILL
CONVENTIONAL WTP SOLIDS HANDLING r2
SCALE: NONE
IFLOW SCHEMATIC
CONVENTIONAL TREATMENT
CITY OF LODI — SURFACE WATER TREATMENT FACILITY
DATE
6/19/07
6/19/07
FIGURE
FIGURE
fl
Table 8. Conventional Treatment Alternative Design Criteria
Draft Technical Memorandum
Item
Value
Low Lift Pump Station:
Pump Station Dimension
50 feet x 60 feet
Number of Pumps
4 (3 working, 1 standby)
Pump Capacity
3,000 gpm @ 30 feet TDH
Pump Motor Information
1,800 rpm max; 40 HP each
Flash Mix:
Inline Mixer
2 HP
Mixing intensity (G Value)
1,000 Second:'.
Flocculation Basin (3), Each Basin:
Flow
3,000 gpm
Detention Time
20 minutes
Volume
8,021 cubic feet
Length
40 feet
Width
16 feet
Water Depth
12.5 feet
Sedimentation With Plate Settlers (2), Each Plate Settler:
Flow
4,500 gpm
Detention Time
30 minutes
Volume
135,000 gal
Length
50 feet
Width
24 feet
Water Depth
15 feet
Surface Loading For Each Plate
0.3 gpm/ftZ.
Dual Media Filters (4 total, 3 working 1 standby), Each Filter:
Flow
3,000 gpm
Max Filtration Rate
6.0 gpm/ftZ.
Filter Area
500 square feet
Filter Media
24 inch anthracite and 12 inch sand
Backwash Water
20 gpm/ftZ. maximum
Backwash Air
5 scfm/ftZ. maximum
UV Reactors (3 total, 2 working 1 standby), Each Reactor:
Maximum Flow
4,500 gpm
Average Flow
3,000 gpm
Minimum Flow
1,500 gpm
Design Dose
40 mJ/cm?. (for 4 log Cryptosporidium disinfection)
Filtered Water UV Transmittance
55 percent
Clearwell:
City of Lodi 23
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Draft Technical Memorandum
Item
Value
Capacity
2.0 MG
Dimension
120 feet diameter by 24 feet deep
Baffling system
Hypalon baffles to achieve T.101T ratio of 0.75
High Service Pumping:
Pump Station Dimension
50 feet x 60 feet
Number of Pumps
4 total (3 working, 1 standby)
Pump Capacity
3,000 gpm @ 200 feet TDH
Pump Motor Information
1,800 rpm max; 200 HP each (2 motors operated with VFDs)
Backwash Holding Basin:
Dimension
70 feet x 70 feet x 12 feet (deep)
Volume
432,000 gallon (two filter backwash volumes)
Backwash Recovery Plate Settler:
System Components
Flash mix tank, flocculation tank, inclined plate clarifier,
thickener
Capacity
1.5 MGD
Residuals Handling System [1]:
Design solids generation rate
900 Ib/day (dry solids basis)
Plate Settler/Gravity Thickener Footprint
20 feet W x 30 feet L x 25 feet H
Dewatering Equipment Type
Slow speed screw press
Dewatering Equipment Feed Rate
50 gpm
Equipment Area Dimension
40 feet x 60 feet
Chemical Area (include Alum, NaOH, Polymer, Chlorine, PAC, NaHSO.3., H.2.O.2.):
Dimension
60 feet x 60 feet
Alum Dose
20 mg/L maximum, 10 mg/L average
NaOH Dose
20 mg/L maximum, 10 mg/L average
Polymer Dose
0.5 mg/L maximum, 0.2 mg/L average
Chlorine Dose
2.5 mg/L maximum, 1.0 mg/L average
PAC Dose
15 mg/L maximum, periodic for T&O control
NaHSO.3.
3 mg/L maximum (optional)
H.2.O.2.
3 mg/L maximum (optional)
1. If residuals are discharged to the sewer, the screw press will not be needed and 600 sf
less building space will be required.
Building Considerations
The chemical storage and feed systems, and dewatering equipment should be housed in a single
building or two separate buildings. In addition to the above, building space should be provided
for a lobby, offices for operations staff, a meeting room, a small laboratory for routine water
quality analysis, storage room, and a maintenance/workshop room. The building architecture
will be selected to enhance and compliment the surrounding area.
City of Lodi 24
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Site Layout
Draft Technical Memorandum
A conceptual site layout of the conventional treatment process is presented in Figure 3.
Capital and O&M Costs
Capital and O&M costs for conventional treatment are presented in Table 9. These are planning
level costs for purposes of comparing conventional and membrane treatment alternatives. The
cost estimates do not include additional elements of the project such as well site improvements
and distribution piping additions, nor do they reflect a specific site and associated development
costs. This preliminary estimate assumes that sludge is dewatered on-site and then hauled to a
landfill for disposal.
City of Lodi 25
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��TOTAL AREA
=390'x540'
RAW WATER RESIDUALS TREATED =4.83 ACRES
HANDLING AND BACKWASH WATER
STATION SLUDGE HOLDING POND PUMP
DEWATERING STATION
BUILDING 1.3 MG CLEARWELL 40'
50'x60' 70'x70' 50'x60'
60'x70' 100'0 TYP
o a
to J
U
r� FILTERS
45'x90'
RIT C
'NTC
20 x20
FLASH MIX, FLOCCULATION,
SEDIMENTATION BASINS,
PLATE SETTLERS OR ACTIFLO
48'x90' ,(E, SLEARWELL
EXPANSION AREA \ /
CHEMICAL OPERATIONS
BUILDING BUILDING PARKING LOT
60'x70' 60'x100'
PLANT ENTRANCE
PLANT LAYOUT
SCALE: 1"=50'
PLANT LAYOUT
L CONVENTIONALTREATMENT 6/19/07
FIGURE
CITY OF LODI - SURFACE WATER TREATMENT FACILITY 3
fl
Draft Technical Memorandum
Table 9. Conventional Treatment Alternative Capital and O&M Costs Preliminary Estimates
Item
Unit Cost
Quantity
Total
Mobilization, Demobilization, General Conditions
$
1,500,000
1
$
1,500,000
Site work(general)
$
850,000
1
$
850,000
Landscaping
$
250,000
1
$
250,000
Site Piping
$
1,500,000
1
$
1,500,000
Raw Water Pump Station - 9,200 gpm
$
700,000
1
$
700,000
Flash mix, flocculation and sedimentation basin
$
0.28
12,000,000
$
3,360,000
Dual media filters, sf
$
1,800
2,000
$
3,600,000
Chemical Systems
$
800,000
1
$
800,000
Finished Water Storage Tank 1.3 MG steel
$
0.65
1,300,000
$
845,000
Finished Water Booster Pump Station - 8,340
pm
$
800,000
1
$
800,000
Backwash holding tank
$
0.80
300,000
$
240,000
Backwash Residuals Handling System
$
1,200,000
1
$
1,200,000
Operations Building - 15,000 SF
$
200
10,000
$ 2,000,000
SUBTOTAL
$
17,645,000
Electrical Power Distribution Systems
$
2,647,000
Instrumentation and Controls
$ 529,000
SUBTOTAL WTP
$
20,821,000
Unaccounted for Items 5%
$
1,041,000
Contingency 20%
$ 4,164,000
TOTAL CONSTRUCTION COST
$
26,026,000
Engineering: design, services during
construction, and construction management
$
5,205,000
Bond financing expenses (does not include
interest)
$ 312,000
TOTAL CAPITAL COST
$
31,543,000
ANNUAL O&M COSTS
CHEMICALS:
CHLORINE (CT, 3 mg/L)
POLYMER (0.2 PPM, FILTER AID)
ALUM (12 PPM)
LABOR, HR
POWER @ $.07/kW hr
SLUDGE DISPOSAL, LS
SED BASIN & FILTER EQUIP REPLACEMENT
$0.30
$5
$0.15
$40
$0.07
$24,000
$35,000
54,750
3,650
440,000
9,000
3,910,000
1
1
$16,425
$18,250
$66,000
$360,000
$273,700
$24,000
$35,000
TOTAL ANNUAL O&M COSTS
PRESENT WORTH O&M COSTS
5%, 20 years
$793,375
$9,887,000
TOTAL PRESENT WORTH
$41,430,000
City of Lodi 27
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Membrane Treatment Alternative
Schematic
Draft Technical Memorandum
A schematic of the membrane treatment process train for the City of Lodi SWTF is shown in
Figure 4.
Design Criteria
The design criteria of the membrane treatment system based on a pressure vessel membrane
configuration are summarized in Table 10.
City of Lodi 28
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AP GI,
Cl2, NaOH
JOKELUMNE
RIVER
48"
INS
MEMBRANE BWW
HIGH
OW LIFT
GRIT
FLASH
FLOCULATION FEED PUMP AUTO NIENIBRANE CLEARWEL'L
SERVICE
PUMPING
F
PS
REMOVAL
MIX
BASIN STRAINER MODULES
SC EN
MEMBRANE
TREATMENT
SCALE: NONE
ALUM.
POLM
NON—POTABLE
PLATE
WATER SYSTEM
__c7_
SETTLER
c__ ==>
=>
RECYCLE
BACKWASH WASTE
FLOCULATION
HOLDING BASIN
CHAMBER
L-Er�
SLUDGE
MECHANICAL
TO
TO Dm
HOLDING BASIN
DEWATERING
i
OO OO O LANDFILL
HOLDING TANK
MEMBRANE
SOLIDS HANDLING
SCALE: NONE
FLOW SCHEMATIC
Lm MEMBRANETREATMENT
17��
6/19/07
FIGURE
CITY OF LODI — SURFACE WATER TREATMENT FACILITY
4
fl
Table 10. Membrane Treatment Alternative Design Criteria
Draft Technical Memorandum
Item
I Value
Low Lift Pump Station:
Pump Station Dimension
50 feet x 60 feet
Number of Pumps
4 (3 working, 1 standby)
Pump Capacity
3,000 gpm @ 30 feet TDH
Pump Motor Information
1,800 rpm max; 40 HP each
Flash Mix:
Inline Mixer
2 HP
Mixing intensity (G Value)
1,000 Second:'.
Flocculation Basin (3), Each Basin:
Flow
3,000 gpm
Detention Time
10 minutes
Volume
4,011 cubic feet
Length
40 feet
Width
8 feet
Water Depth
12.5 feet
Feed pumps/Autostrainers:
Feed pump:
Number
Capacity
Horsepower
1 per train
1,500 gpm @80 ft TDH
40 hp
Autostrainers Type/Number
Automatic Self-cleaning with 0.5 mm screen/3
Flow
3,000 gpm
Membrane Trains (7 total, 6 working 1 standby), Each Train:
Net Capacity
2.0 MGD
Number of Modules per train
84
Water Temperature
15°.0 Summer, 5°.0 Winter
Instantaneous Flow per Module
17.5 gpm
Design Flux
55 gal/SF/day (gfd)
Backwash Interval
30 minutes
CIP Interval
60 days
Chlorine Maintenance Wash Interval
36 hours
Acid Maintenance Wash Interval (if
needed
120 hours
Estimated Recovery
95%
C I P Waste
1,400 gpd
Maintenance Wash Waste
22,400 gpd
Clearwell:
Capacity
2 MG
Dimension
120 feet diameter by 24 feet deep
Baffling system
Hypalon baffles to achieve T.101T ratio of 0.75
City of Lodi 30
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Draft Technical Memorandum
Item
Value
High Service Pumping:
Pump Station Dimension
50 feet x 60 feet
Number of Pumps
4 (3 working, 1 standby)
Pump Capacity
3,000 gpm @ 200 feet TDH
Pump Motor Information
1,800 rpm max; 200 HP each (2 motors on VFDs)
Backwash Holding Tank:
Dimension
40 ft diameter x 16 ft high
Working Volume
130,000 gallon
Backwash Recovery Plate Settler:
System Components
Flash mix tank, flocculation tank, inclined plate clarifier,
thickener
Capacity
1.0 MGD
Residuals Handling System[l]:
Design solids generation rate
500 Ib/day (dry solids basis)
Plate Settler/gravity thickener footprint
15 feet x 25 feet
Dewatering Equipment Type
Slow speed screw press
Dewatering Equipment Feed Rate
25 gpm
Equipment Area Dimension
30 feet x40 feet
Chemical Area (include Alum, NaOH, Polymer, Chlorine, PAC, NaHSO.3., H.2.O.2.):
Dimension
60 feet x 60 feet
Alum Dose
20 mg/L maximum, 10 mg/L average
NaOH Dose
20 mg/L maximum, 10 mg/L average
Polymer Dose
0.5 mg/L maximum, 0.2 mg/L average
Chlorine Dose
2.5 mg/L maximum, 1.0 mg/L average
PAC Dose
15 mg/L maximum, periodic for T&O control
NaHS0.3.
3 mg/L maximum (optional)
1-1.2.O.2.
3 mg/L maximum (optional)
1. If residuals are discharged to the sewer, the screw press will not be needed and 600 sf
less building space will be required.
Building Considerations
The membrane equipment, chemical storage and feed systems, and dewatering equipment
should all be housed in a single building or separate buildings. In addition to the above,
building space should be provided for a lobby, offices for operations staff, a meeting room, a
small laboratory for routine water quality analysis, storage room, and a maintenance/workshop
room. For prudent planning, the building should be oversized to accommodate addition of
future membrane trains should they be needed. The building architecture will be selected to
enhance and compliment the surrounding area. Examples of membrane plant operations
buildings are shown in the photos below.
City of Lodi 31
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Draft Technical Memorandum
Membrane Operations Building (Yucaipa Valley Water District)
Membrane Operations Building (Roanoke, VA)
Site Layout
A conceptual site layout of the membrane treatment process is presented in Figure 5.
City of Lodi 32
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V- TOTAL AREA
390'x540'
RAW WATER
PUMP
STATION
RESIDUALS
HANDLING AND
SLUDGE
DEWATERING
BACKWASH
HOLDING TANK
TREATED
WATER
PUMP
STATION
=4.83 ACRES
BUILDING
1.3 MG CLEARWELL '
50'x60'
40'D
50'x60'
40
60'x70'
100'0 TYP
❑
CHEMICAL
BUILDING
GRIT
20'x20'
FLASH MIX.
FLOCCULATION
20'x40'
60'x70'
((F,
SLEARIIR/ELL
EXPANSION AREA
\ /
IOPERATIONS/MEMBRANE
I
BUILDING
PARKING LOT
I
60'x220'
I
PLANT ENTRANCE
I
PLANT LAYOUT
SCALE: 1"=50'
PLANT LAYOUT
L MEMBRANE TREATMENT 6/19/07
FIGURE
CITY
OF LODI - SURFACE WATER TREATMENT FACILITY 5
fl
Capital and O&M Costs
Draft Technical Memorandum
Capital and O&M costs for membrane treatment are presented in Table 11. These are planning
level costs for purposes of comparing conventional and membrane treatment alternatives. The
cost estimates do not include additional elements of the project such as well site improvements
and distribution piping additions, nor do they reflect a specific site and associated development
costs. This preliminary estimate assumes that sludge is dewatered on-site and then hauled to a
landfill for disposal.
Table11. Membrane Treatment Alternative Capital and O&M Costs Preliminary Estimates
Item
Unit Cost
Quantity
Total
Mobilization, Demobilization, General Conditions
$1,500,000
1
$ 1,500,000
Site work(general)
$850,000
1
$ 850,000
Landscaping
$ 250,000
1
$ 250,000
Site Piping
$1,500,000
1
$ 1,500,000
Raw Water Pump Station - 9,200 gpm
$700,000
1
$ 700,000
Autostrainers
$250,000
1
$ 250,000
MF Membrane Filtration System 12 m d
$ 0.60
12,000,000
$ 7,200,000
Chemical Systems
$ 500,000
1
$ 500,000
Finished Water Storage Tank 1.3 MG steel
$0.65
1,300,000
$ 845,000
Finished Water Booster Pump Station - 8,340
pm
$800,000
1
$ 800,000
Backwash holding tank
$0.80
100,000
$ 80,000
Backwash Residuals Handling System
$800,000
1
$ 800,000
Operations Building - 15,000 SF
$200.00
15,000
$ 3,000,000
SUBTOTAL
$18,275,000
Electrical Power Distribution Systems
$ 2,741,000
Instrumentation and Controls
$ 548,000..
SUBTOTAL WTP
21,564,000
Unaccounted for Items 5%
$ 1,078,000
Contingency 20%
$ 4,313,000 .
TOTAL CONSTRUCTION COST
$ 26,955,000
Engineering: design, services during
construction, construction management
$ 5,391,000
Bond financing expenses
$ 323,000
City of Lodi 34
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Draft Technical Memorandum
Item
Unit Cost
Quantity
Total
TOTAL CAPITAL COST
$32,669,000
ANNUAL O&M COSTS
CHEMICALS:
Unit Cost
Quantity
Total
CHLORINE (CT), LB
$0.30
54,750
$16,425
CHLORINE (CIP), LB
$0.30
12,000
$3,600
CITRIC ACID (50% W/W), LB
$0.50
4,000
$2,000
SODIUM BISULFITE (38% W/W), LB
$0.50
3,400
$1,700
SODIUM HYDROXIDE (50% W/W), LB
$0.08
3,400
$272
ALUM (3 PPM), LB
$0.15
92,000
$13,800
LABOR, HR
$40
7,000
$280,000
POWER @ $.07/kW hr
$0.07
4,038,000
$282,660
SLUDGE DISPOSAL, LS
$4,000
1
$4,000
MEMBRANE REPLACEMENT (10 YEAR LIFE),
$25,000
LS
1 $25,000
1 1
TOTAL ANNUAL O&M COSTS $613,032
PRESENT WORTH O&M COSTS (5%, 20
$7,640,000
YEARS)
TOTAL PRESENT WORTH (CAPITAL + PW
O&M) $40,309,000
Advantages and Disadvantages of Alternatives
Both conventional filtration and membrane filtration can be used at the proposed City of Lodi's
SWTF. The advantages and disadvantages of membrane filtration compared with conventional
medial filtration are summarized in this suction.
Advantages
The advantages of the membrane process are:
➢ Membranes provide a positive barrier for the removal of all microbials and
most pathogens, which increases the flexibility of the system to meet future
regulations.
➢ The overall footprint for the facility is smaller than conventional surface water
treatment processes.
➢ The overall treatment process is easy to expand by adding trains.
City of Lodi 35
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falDraft Technical Memorandum
➢ With the automation of the process and the entire plant, the operational
personnel requirement is lower.
➢ Less pretreatment is required only flocculation is needed. Sedimentation is not
necessary.
➢ Less disinfection is required and thus lower DBP concentration is expected.
➢ Less chemical for flocculation and pH adjustment is needed.
➢ The operation of the facility is flexible to accommodate changing raw water
quality.
➢ The total present worth of the membrane alternative is slightly less than for the
conventional treatment alternative.
The advantages of Conventional treatment are:
➢ It is a proven process with many years of experience.
➢ The capital cost is slightly less than for membranes.
Disadvantages
The disadvantages of the Membrane process are:
➢ During high turbidity events of winter runoff, the plant capacity may be
reduced and the City's groundwater wells may have to be used as the primary
source of water supply. This is not a significant problem because the wells
have ample capacity to meet winter demands.
➢ The membrane treatment system will require approximately 2.5 percent more
power consumption compared to conventional filtration.
The disadvantages of Conventional treatment are:
➢ Conventional filtration relies on chemical destabilization of particles for
pathogen removal and is not as reliable as membrane treatment.
➢ Greater chemical usage and annual operating costs.
➢ Higher present worth cost.
City of Lodi 36
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falDraft Technical Memorandum
Recommendations
Based on the evaluation presented above, it is our recommendation that the City select low
pressure membrane filtration for the proposed SWTF. The decision on which low pressure
membrane system to use will be made based on further evaluation during the predesign stage.
The City could decide whether to pre -purchase the membrane system after further evaluation of
individual membranes or provide a general design and select the membrane system during the
project bid period.
City of Lodi 37
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. . . . . . . . . . . . . . .
PUM
CY In INC it
OP). f r
ol
0.
VL -'Of Pr�.',.Objectia4; gy� O
Establish expected raw water quality and treated
water goals for design
�X :.
t:
Estimate exsected water suaaly. future demands. and
Determine best technology considering water quality
and costs
w
TOC concentrations
Giardia and al
lity
����
slightly elevated requ rrn �„ r
o
,,,,,,,,,,,,,,,,,
removal
Turbidity
is normally
\\Q\\ \\\\\Q\Q\Q\Q\Q\Q\Q\\\Q\Q\Q Q\Q\\\Q\Q\Q\Q\Q\
less than 10
Levels above 50 NTU
dhigpossible
run-otr events
':.
14
n o
Water S,"aPE Y
.
-5 1 d ra"
1C;
VE ,
• In 2010 the available su pI
63000 AFY plu's''3,000 AFY or bed wate
Existing we hot;
day rotation limitingRive us
during fall, winter, and spring
*Up to 12 000 AFY of WID may becom" �
available for future demands
�upp�y
aat'j,'''ent
Available
2010 1 9,000 (3/1 to 10/15)
2010 1 9,000 (year round)
2030 1 129000 (3/1 to 10/15)
2030 1 12,000 (year round)
Ing
MVE
ip
12
26
16
Wf
I
1
fi.ti f
0�
,
convent''i0n,aT,
„
V`
nc u es
war ii' ,
Coagulant addition aln
MIA. r
Flocculati' ','.and P edJ
�. �,.,.,
IS \11
Dual ifiltraticmed a
• 1 \6111101
UV disinfectionMIMI
Chlorination for residual
%�///111
Top— —
ent
MO�ELUMN--
f211iER
REG
48"
INITAICE
LOW LIFT nRIT
FISH PS REMOVAI
SCREEN
BACKWASH WASTE
HOLDING BASIN
ALUV, RCLM,
NaUH PAC
FLASH FLOCULATION
M1x BASIN
C12
5,EDIMEN7ATIGN, FILTER.
BA
BASIN MEDIA
Cis H202 NdHSn3
HO -GING BVAW
BASIN
CONVENTIONAL TREATMENT
5.CALE: NONE
NON—POTABLE
WATER SYSTEM
LATE
SETTER
RECYCLE TO HEAD
DF WTP (REC)
FLOCULATION
CHAMBER
;q .SLUDGE
MECHANICAL TO
TO BWV' pE'NATERING LANDFILL
HOLDING BASIN O0 OG Q
HOLDING TANK
CONVENTIONAL WTP SOLIDS HANDLING
SCALE: PtONE
IIICH
W CLEARWELL SERVICE
PUMPING
iinventiona i vreazr
Ir rp-slirIP.."K"'"au1........rec
Residuals
Handling and
► Sludge
Dewatering
Otan Building
(50'x 60') (60'x 70')
Flash Mix, Flocculation Filters (45'
Sedimentation (48'x 90') x 901)
Treated
Water
Pump
Station
(50'x 60')
Parking Lot
Plant Entrance
M m r n �.I re
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Occasionat a of, fcoa
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*Membrane moduIes in res
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*Chlorination for residual
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INTAKE
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FISH PS REMOVAL MIX
SCREEN
MEMBRANE
FLOCULATION FEED AUTO
BASIN PUMP STRAINER
MEMBRANE TREATMENT
SCALE: NONE
ALUM,
POLM NON—POTABLE
BWW
Cl2, NaOH
MEMBRANE
MODULES
WATER SYSTEM
PLATE
SETTLER
RECYCLE
BACKWASH WASTE FLOCULATION
HOLDING BASIN CHAMBER
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MECHANICAL LA
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HOLDING BASIN OO OO 0
HOLDING TANK
MEMBRANE SOLIDS HANDLING
SCALE: NONE
HIGH
CLEARWELL SERVICE
PUMPING
FLOW SCHEMATIC °"'I
hDR MEMBRANE TREATMENT 6/1 q/07
F19WE
CITY OF LODI — SURFACE WATER TREATMENT FACILITY 4
amorant
Residuals
Handling and
► Sludge
Dewatering
Ptan Building
(50'x 60') (60'x 70')
Flash Mix
Flocculation
(20' x 40')
Chemical
Building
(60' x 70')
P"dF
is
BW
Tank
PW
Treated Water
Pump
Station
(50'x 60')
et
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cAlternative"'"'L"''Ost, GO�ti
R
R
($ millions prelim"inary estima�esfo
Treatment Capital Present
Alternative Cost Worth
O&M
Costs
Total
Present
Worth
A
IL
zecemmencfat�a
• Water quality relies on chemicals
• Older technology
• Higher PW cost
• Membranes provide positive barrier
for reliable high quality water
• New and improving technology
• Easier operation and lower PW cost
• Much less chemical use required
Smaller footprint
Pa rks'&,
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Site,A Lod
• Site has beenyuodevelo ed sInc \ t \ n
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• Various development concepts''\
p
considered but t sere is ,no ado \suer \ \
t
•Uses to consid
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DISCOVer�/ c
N
❖ Fireworks ❖ , vvvyv
•
Opportunity to create master _plan and beg i n
development of site
• Commission supports location and Parks
Recreation Dept. participation underway
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Site B
W. Lodi Avenue