Multi-State Salinity Coalition
February 18, 2011
Navigating the Regulatory and Permitting
Hurdles for Concentrate Discharge
Kipp Scott, East Cherry Creek Valley Water and Sanitation District
Doug Brown, P.E. CDM
Presentation Outline
 Background on ECCV Project
 Overview of Brackish Water Reverse Osmosis (RO)
Treatment
 Factors Affecting Residuals Disposal for Inland
Facilities
 Disposal Alternatives and Regulatory Issues
Southeastern Denver Has Limited Surface Water
Supplies and Relies on Imported Water or Deep
Non-tributary Groundwater
Existing ECCV Water Supply Is Being
Depleted and Is Not Renewable
 ECCV initially relied on
dozens of non-tributary
groundwater for its
water supply
 The Arapahoe and
Laramie/Fox Hills
aquifers have less than
300 mg/L TDS and 100
mg/L hardness
1 mile
ECCV Is Diversifying and Conserving Its
Water Supply
 Non-potable Irrigation
with Reclaimed Water
 Denver Treated Water
 Block Water Rates
 Conservation Incentives
Reduced Demand 30%
from 1995
ECCV Water Well Production will Decrease
50% in 10 Years Requiring 377 New Wells
The Northern Project
 Beebe Draw alluvial wells
 Phase I water rights – 70
Ranch
 Phase II water rights – Barr
& Milton shares
 Phase I facilities
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Well field
Pump Stations
Waterline
Renewable Groundwater from Northern Project
Being Blended with Other District Supplies
Water Treatment Planning Objectives
 Consistent quality product
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Free of objectionable taste and odors
Water quality meets end user requirements
Consistently meets drinking water standards
 Specific water quality targets
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Total Dissolved Solids < 300 mg/L
Total Hardness < 100 mg/L
 Firm treatment and pumping capacity to meet peak
demands
 Reliable service
 Reasonable operating costs
Selection of Water Treatment Process
 High hardness and TDS required blending or
reduction of these compounds
 Blending is not a long-term solution

Lack of long-term blending sources
 Reverse Osmosis selected
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Most cost-effective for TDS
Only effective process to consistently meet water
quality goals
Also eliminates almost all other potential
contaminants from effluent dominated sources
 The challenge is the disposal of the concentrate
stream (brine) from the treatment process
ECCV Northern
Water System
47 MGD Ultimate
Capacity
Overview of RO Process and Concentrate
Disposal
 Typical low pressure RO operating at 85%
recovery treating GW with 700 mg/L TDS &
300 mg/L hardness
 6.7 MGD of permeate
blended with 3.3 MGD
of UV treated well
water
 1.2 MGD of
concentrate with 5000
mg/L TDS
RO Concentrate Disposal Options
1. Discharge to Sanitary Sewer System or POTW
Discharge
2. Surface Water Discharge through NPDES permit
a.
b.
navigable waters
irrigation ditches
3. Deep Well Injection
4. Beneficial Uses
5. Zero Liquid Discharge Using:
a.
b.
c.
thermal/mechanical evaporation systems
enhanced evaporation system
passive evaporation basins
50
45
40
35
30
25
20
15
10
5
0
50
45
40
35
30
25
20
15
10
5
0
Mass of Salt Discharged is Constant
50
60
70
80
Recovery Percent
90
100
Concentrate Volume %
RO Concentrate TDS ppt
(assume 1000 mg/L raw water)
Brine Concentration & Volume Vs. Recovery
Potential Impacts of RO Concentrate on
Wastewater Treatment Plant
1. Decreased hydraulic residence time and
2.
3.
4.
5.
6.
potential impacts on effluent BOD and TSS
Increase in effluent TDS
Potential Increase in Elements such as
Radionuclides, heavy metals, nitrates
Potential Inhibitory Effect on Treatment Biology
at High % of Concentrate
Potential Impact on WET Tests
Potential Impact on Equipment Corrosion
Brackish RO Concentrate Typically Does
Not Exhibit Acute or Chronic Toxicity
Wastewater System Concentrate
Management Options
1. Blend Concentrate with the Treatment Plant
Effluent
2. Send Concentrate Through System During OffPeak Times
3. Pre-treat Concentrate for Specific Contaminants
of Concern: Heavy Metals, Nitrates, Radionuclides
4. Develop a Salt Balance for the Basin to
Demonstrate No Impact on Total Salt Discharge
Adding a RO System to an Existing Water
Supply Results in a Neutral Salt Balance
River
M
Blend
40
tons/day
2.5 mgd
Irrigation
Return
Flow
POTW
Salt
10-mgd
Existing
Brackish
Wells
@ 1,000
mg/L TDS
9.3 mgd
250 mg/L
10 tons/day
Distribution
System
6.8 mgd
7.5
mgd
Sanitary
Sewer
Flow
RO
System
0.8 mgd @ 10,000 mg/L = 30 tons/day of salt
A Wide Range of Commercial and Residential
Activities Add TDS to the POTW Discharge
 Water softeners
 Demineralization for labs, electronics

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manufacturing
Cooling tower blowdown
Boiler feedwater treatment
Beverage production
Laundry operations
pH adjustment
Summary of Potential RO Impacts on
Wastewater Treatment Plants
 Minimal Performance and Water Quality Impacts on
Wastewater Treatment Plants Receiving a Small
Percentage of RO Concentrate
 Potential Hydraulic Impacts if RO Concentrate is a
Significant Percentage of the Wastewater Treatment
Flow
 The Increase in Effluent TDS from a Brackish RO
Concentrate Discharge Can Have an Impact on
Effluent Reuse Options
Surface Water Discharge Options
1. Discharge to surface water
2. Secondary Recovery (Brine Minimization) to
reduce concentrate volume to ~ 3% of RO flow
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Enhanced evaporation and landfill of dry solids
• Use of blowers
• Pond sizing based on annual volume
Deep well disposal
• Initial stage w/o secondary recovery
Discharge to Surface Water Typically
Avoided Since Daily Salt Discharge from a
Brackish RO Project is Significant
Daily Salt Discharge Tons / Day
100
90
Daily Salt Discharge Tons / Day
80
70
60
50
40
Approx. 2400 tons of Road Salt
30
20
Courtesy of NYLCV
10
0
10 mgd BWRO
@2000 mg/L
Colorado Road
Deicing
10 mgd
Municipal
WWTP
10 mgd Water
Softener @ 400 mg/L
As CaCO3
NPDES Permit Can Be Based on Discharge
Standards or Non-Degradation Criteria
 TDS typically is not a discharge standard because
wastewater treatment plant can’t remove it
 Nitrate, metals, radionuclides are concentrated
by RO and can exceed discharge standards
 ECCV discharge permit to irrigation ditch was
based on non-degradation of groundwater and
controlled by Fluoride, uranium and gross alpha
 Acute and chronic toxicity discharge standards
can be impacted by common ion concentration
and ratios
Zero Liquid Discharge (ZLD) Options

Thermal/mechanical evaporation
systems: vapor recompression, spray
dryers, crystallizers

Low tech
evaporation
processes: passive
solar evaporation
basins, enhanced
evaporation basins,
misters, undulating
film evaporators
Photo courtesy GE Infrastructure
Passive Evaporation Basins Require
Extensive Land Even in Southwest Desert
High Recovery RO Using both WAC
and SAC
Conc.
Brine
Ground
Water
Strong Acid
Cation IX
Hardness
Removal

Removes Ions That
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Form Scale
Calcium
Magnesium
Barium
Strontium
Iron
Manganese
Aluminum
Conc.
Brine
Conc.
Brine
Weak Acid
Cation IX
Reverse
Osmosis
Polyvalent
Cations

High Purity
Water
High pH
Separation
Ambient pH RO Operation
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Controls Silica Scaling
Eliminates NaOH Feed
A Low-Cost Solar Basin with an Air Sparger
Can Increase Evaporation Rates
RO Concentrate
Gravel Diffuser Layer
Basin Liners
Air Distribution Grid
Deep Wells Can Be Used for Final Disposal
of Concentrated Brine
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23 operating injection wells in Adams and Weld
Counties (47 permitted by the State O&G Div.)
ECCV well - EPA permit for a Class 1 well
Underground formations 9,000+ feet below
drinking water aquifers and 1,400 ft. above
Rocky Mountain Arsenal wells
Estimated injection rate of 200 to 400 gpm
Estimated cost of $2,280,000 per completed well
+ pipeline from plant to well
Brine Injected Below Potable
Water Aquifers

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
Injection wells include outer casing
and inner casing to create and
annular space that can be
monitored for leaks
Corrosion resistent materials
compatible with salty brines
Chemical stability of brines during
and after injection
31
Deep Well Disposal Option
Secondary concentration of RO concentrate using brine minimization to 3%
of flow treated to minimize water rights loss and # of deep disposal32wells
ECCV Phase 1 Low Pressure RO and
Brine Minimization System
UV Disinfection
3.3 MGD By-Pass Blend
7.8 MGD Ground Water LPRO @ 85%
6.6 MGD Permeate
140 psi
50 mg/L TDS
700 mg/L TDS
1.2 MGD Concentrate
4600 mg/L TDS
10.8 MGD Blend
300 mg/L TDS
Brine Minimization
Pre-treatment
Residuals
High Recovery
RO @ 75%
0.9 MGD Permeate
500 mg/L TDS
0.3 MGD Brine @
18,000 mg/L TDS
Acid
Deep Well Injection
10,000 ft. Deep
Class I Injection Well
High pressure Injection Pump
Total Estimated ECCV ZLD O&M costs
per 1,000 gallons of net water production
Secondary Recovery
and Landfill of Dry
Solids w/
Enahanced Evap.
Deep Well
Injection, No
Secondary
Recovery
Deep Well Injection,
With Secondary
Recovery
Secondary
Concentration
$0.58
N/A
$0.58
Enhanced Evaporation
and Landfill of Dry
Solids
$1.74
N/A
N/A
Deep Well Injection
N/A
$0.08
$0.02
Total ZLD O&M Cost
$2.32
$0.08
$0.60
Thank you, and Time for Questions
 Doug Brown
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303-383-2316 direct
303-915-3042 cell
BROWNDR@CDM.COM