An Overview of Design to Operation of Residual

Management Facilityat

OGDEN DUNES WATER TREATMENT PLANT

Vinod Barot, Ph.D.

November 16, 2010.

2

OGDEN DUNES WATER TREATMENT PLANT

Source of water Lake Michigan Rated capacity 24 MGD Average Daily Demand 10.5 MGD

Two residuals streams

1. Spent filter backwash 2. Sedimentation basin solids

3

Purpose of Improvements

Meet Regulations Indiana Department of Environmental Management (IDEM) Discharge of wastes to rivers, etc was common prior to 1980

RCRA limited solid waste discharges(40 CFR 261.10)Most plants required to recycle or treat wastes prior to

discharge IDEM Notice of Violation: Case No. 2008-18172-W (Dec. 24, 2008) Offer of settlement: Rule 408 of the Indiana Rules of Evidence Cease Discharging Effective Date – June 23, 2009 Rate case

4

Planning and options available

• Black and Veatch – Design consultant• A total of 14 alternatives suggested, Option 11 selected• 2 circular clarifier(65’ diameter) on west end of lagoon in phase 1

• Cost analysis

2.2 M $ structural fill

1 M $ buildingChanged to : Rectangular

open clarifiers connecting each other.

5

Modified Design and construction schedule

Future Gravity Thickener(30’ dia)

Fill in Lagoon(330’x130’)

Future Residuals Dewatering Building (2 story 80’x40’)

Backwash Water Clarifying Basins (120’ x 60’) w/ Pumping Station

Future Sedimentation EQ Basin (60’ x 60’)

LEGEND:

Existing 42” Discharge Line

42” Gravity Pipe from Discharge Line

12” Force Main to Head of WTP

42” Overflow

4” Water Line

Road

MODIFIED SITE PLAN 12/18/2008• Bowen Engineering

contractor as a design builder

• Design modified: 12/18, IDEM general permit submittal: 12/20

• Local permit: 01/14, IDEM Const. permit: 1/20, Approved:1/21

• Materials procurement: 65 day (Bid tab evaluation, submittal, etc)

• Actual construction: 01/29/2009 to 06/23/2009 (start to finish)

6

Are Discharges to Lagoon Allowed After June 23, 2009? NO Is There an Overflow?

Yes, a 20’ wide notch is constructed on the West Tank north wall at Elevation 609.5 (18.5 ft depth)

Will IDEM have to be notified if the tank overflows? Yes Notification is required within “2” hours (verbal) once you

become known. Results of Discharge to Lagoon

A Notice of Violation (NOV) will be issued Public Notification Possible fines to InAW, etc.

Can the 42” Valve to the Lagoon be Opened Opening the valve to the Lagoon is the same as an overflow

7

Description of the Wastewater Facilities

Settling Tanks – Two (2) 36’ x 99’ x 16.5’ deep 16.5 feet to internal overflow (one tank to another) 440,000 gallons total each (below internal overflow)

Supernatant Wet well Receives supernatant from either settling tank Three valves at various elevations allow supernatant from

settling tank into the supernatant wet well Three (3) submersible recycle pumps

Residuals Pump Wet well Receives sludge from either settling tank Two (2) submersible pumps

Recycle Supernatant to “head” of Plant (prior to coagulant)-12” DIP

8

Piping Plan

East Tank

12” Recycle

West Tank

42” Wastewater

Recycle Pumps

Lagoon Overflow Notch

Internal Overflow

Notch

9

Section – Key Elevations

591.0 ft

593.0 ft

597.0 ft

602.0 ft

607.5 ft

609.5 ft OF LAGOON

INTERNAL OF

5.6 FT

5.6 FT

150,000 GAL=5.6 FT

10

How Will the Settling Tanks Operate?

What are the Steps in the Process? Filter backwash water from one filter wash– say 150,000 gallons,

sent to one tank The wastewater is allowed to settle – say 6 hrs Settling - Settled water (supernatant) is decanted from the top – Recycle pumps return the supernatant to head of the plant at a

controlled rate

What is the usable volume in each tank? Allowing for say 3 ft of non-usable volume at the bottom of each

tank Allowing for 6 inches of non-usable volume before internal

overflow (at 16.5’) Storage Volume = 350,000 gallons (each tank) Allows for two washes per tank 150,000 GAL = 5.6 FT----------------26,660 GAL/FT

11

New Terms for Ogden Dunes

Supernatant

“Decant” Supernatant

“Recycle Supernatant to the Head of the Plant”

Wastewater Settling Tank

12

Will the Recycle Affect Treatment Performance

Studies of recycle at other plants have shown: Some increase to settled turbidities No impact to filtered turbidities

How much settling time is required? No regulations on settling time 6 hours is reasonable Settling time will be adjustable

Will coagulant dose have to be increased during recycle? A recycle flow of 440 gpm = 0.63 MGD Coagulant dose must consider additional flow (if low service

pump flow unchanged) Dose may have to be changed when recycling

13

How Much Will Filter Backwash Water Settle?

Try It in a Jar: Grab a sample during backwash

Composite sample is best Allow Settling Time - hours Measure supernatant turbidity

Add 50 ml of supernatant to 950 ml of raw water Equivalent to 5% recycle Check turbidity before and after adding supernatant Jar Test before and after adding supernatant

14

How are Recycle Pumps Controlled?

Two Modes – Fixed Flow – Operator sets GPM Setpoint Percent Flow – Operator sets % of Raw Flow

What is the minimum flow from one pump? 250 gpm when tanks are low 440 gpm when tanks are high

What is a typical recycle rate? Studies of many plants have shown that rates of 10% or less have

minimal impact on operation – so operating guideline is 10% or less is allowed

A 5% recycle rate is good for normal operation How do you calculate 5% rate?

12 MGD x 694 x .05 = 416 gpm 18 MGD x 694 x .05 = 625 gpm

15

How Long to Recycle from a Backwash?

Calculation: Assume backwash = 150,000 gallons Assume recycle rate = 440 gpm 150,000 / 440 = 341 minutes = 5 hours, 41 minutes of recycling

(following settling)

If Plant Flow = 24 MGD Assume recycle rate = 5% Recycle flow = 830 gpm 150,000 / 830 = 3 hours (following settling)

16

Simulation of 1 Backwash and Recycle

Wastewater Clarifier and Recycle OperationOne Backwash per Day

0.01.02.03.04.05.06.07.08.09.0

10.011.012.013.014.015.016.0

12:15 AM

2:00 AM

3:45 AM

5:30 AM

7:15 AM

9:00 AM

10:45 AM

12:30 PM

2:15 PM

4:00 PM

5:45 PM

7:30 PM

9:15 PM

11:00 PM

Time of Day

Ta

nk

1 L

ev

el

0

200

400

600

800

1,000

1,200

1,400

1,600

Re

cy

cle

Flo

w, g

pm

Tank Level 1 Recycle Flow

SETTLE

RECYCLE

17

Two Backwashes-Example

Wastewater Clarifier and Recycle OperationTwo Backwashes per Day in 1 Tank

0.01.02.03.04.05.06.07.08.09.0

10.011.012.013.014.015.016.0

12:15 AM

2:00 AM

3:45 AM

5:30 AM

7:15 AM

9:00 AM

10:45 AM

12:30 PM

2:15 PM

4:00 PM

5:45 PM

7:30 PM

9:15 PM

11:00 PM

Time of Day

Ta

nk

1 L

ev

el

02004006008001,0001,2001,4001,600

Re

cy

cle

Flo

w, g

pm

Tank Level 1 Recycle Flow

SETTLE

RECYCLE

18

How is Sludge Removed from Tanks?

Sludge Removal Required once or twice per year Fire hose to submersible pumps Clean one tank at a time

Can Plant operate with one tank out of service? Yes

Dewatering Portable dewatering

19

Controls

Automated Process with Input from Operator Graphic Displays Trending of Levels, Flows Wastewater Tank Inlets – 42” valve with electric operator Decant Valves – (3) 16” Valves with electric operator Recycle Pumps – Flow Control Mode or % Recycle Mode

3 pumps, each with VFD Recycle Flow Meter - Magmeter

Level Monitors Each Tank Each Wetwell High Level Switches and Alarms

Recycle measurements by Turbidimeter

20

Special Thanks goes to……….

Ken Buczek Steve Creel James Reilly

21

Thank YouQuestions/Comments