Transcript Slide 1

City of Allegan
Conversion of Lime Softening to
Reverse Osmosis Softening
Background
The existing lime softening
plant was constructed in the
early 1970’s to service the
City and local industries
with high quality softened
groundwater from a well
water source along the
Kalamazoo River in the City
of Allegan (100 – 150 mg/l
hardness)
Existing Plant Facts


Two upflow clarifiers, two
rapid sand filters,
originally rated at 3 mgd.
1977 and 1999
modifications were made
to the clarifiers to improve
performance
Existing Plant Schematic
Existing Problems


No standby power at
treatment plant
Remote well can directly
pump to system but with
no treatment
Existing Problems


Site along Kalamazoo
River in the floodplain,
frequently floods which
restricts access and
requires sandbags around
the wells
Lime delivery can be
problematic
Existing Problems


All of the equipment is
original to the plant and
has outlived its useful life.
Building and HV systems
are old and in need of
replacement
Study Phase



Examined upgrading lime plant versus retrofitting to RO
treatment
Study concluded that retrofit to RO was most cost
effective
Proceeded with Pilot study of RO technology on existing
well water in 2006
Study Phase

Pilot Study



Conducted in 2006 for
treatment performance
2nd study conducted in 2009
to determine characteristics
of concentrate for NPDES
permit
Spiral wound Film Tec
BW30LE-440 Membranes
used in both studies
Study Phase

Pilot Study Conclusions






No significant scaling
Flux Rate 14 gfd
70%+ Recovery for membranes
Minimal fouling
Iron remained in soluble form – no pretreatment required prior to
membranes
Concentrate stream did have detectable phosphorus, even with
low P antiscalant
Project Plan Phase




Stimulus funding available in 2009
Reexamined issues – new plant on existing site or new
plant elsewhere due to flooding concerns
Completed DWRF Project Plan while simultaneously
designed plant in Spring/Summer 2009
New plant on existing site was the most cost-effective
alternative
Permitting Phase

Wetlands/Floodplain
permit application



HEC analysis of
Kalamazoo River
Cut back existing lime
sludge lagoons for
compensating cut for new
fill on site
Raised new plant above 500
year flood level
Permitting Phase

NPDES permit
application for RO
concentrate discharge



Potable water, high in TDS
and measurable Phosphorus
TMDL on Kalamazoo
River for Phosphorus
Reallocated portion of
City’s WWTP Phosphorus
allocation to WTP
Plant Design Features

Cartridge Filters


5 micron
Reverse Osmosis
Treatment Skids




Permeate Quality = 0 mg/l
Hardness
Total capacity = 3.45 mgd
when blended at 100 mg/l
Hardness (3 skids)
2 Stage RO
Interstage boost system
Plant Design Features

Raw Water Feed Test
Panel


pH, SDI, Temp, Pressure,
Conductivity
Membrane Clean-in-Place
system

Immersion heater
Plant Design Features

Three Iron Removal Filters




Air/Water simultaneous backwash
Automatic control backwash system
Automatic RO Permeate/Iron Filter Water blend control
system
Air stripper for pH adjustment for RO permeate
Plant Design Features

High Service Pumping



Five, horizontal split case
high service pumps (2
pressure districts)
Total firm pumping
capacity = 4.8 mgd
500,000 gallon on site
storage tank
Plant Design Features

Three on-site wells



One new well (abandon
existing well)
Retrofit two existing wells
with submersible pumps
(VFD control)
Total firm pumping
capacity = 3.0 mgd
Plant Design Features

Chemical feed





On site mixed oxidant
generation (iron oxidation,
disinfectant)
Fluoride (dental)
Antiscalant (membrane feed)
Phosphate (corrosion
control)
Caustic soda (pH adjustment)
Plant Design Features



Membrane Solar panels
incorporated into metal
roof
Camera/intrusion security
system
Automatic sampling
system for concentrate
discharge to Kalamazoo
River
Plant Design Features



SCADA system for
automatic control of entire
plant, 24/7
Complete Laboratory
Water meter testing area
Funding

Final Project Funding





$3,744,000 EDA Grant
$3,744,000 DWRF Low
Interest Loan
$2,501,000 Stimulus Loan
Forgiveness
Total project cost
$9,989,000
Grant = 63% of total
project cost
Construction Phase



Began construction in
February, 2010
Scheduled to begin
operation of new plant in
early 2011
Construction to be
completed by Fall, 2011