Energy Assessment Report for County of Kauai Waimea Wastewater Treatment Plant


April 7, 2010

Energy Assessment Report for

County of Kauai

Waimea Wastewater
Treatment Plant

U.S. Environmental Protection Agency Region 9
Waimea WWTP is located at 9275 G
Kaumualii Highway, Waimea, Hawaii

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Energy Assessment Report - County of Kauai, Waimea WWTP

SECTION 1
Executive Summary

Under contract to USEPA, Tetra Tech Inc., (Tetra Tech) performed a site energy assessment
of the Waimea Wastewater Treatment Plant (WWTP) facility. The facility is located on the
island of Kauai at 9275 G. Kaumualii Highway, Waimea, Hawaii . Representatives from the
Waimea WWTP provided access to the facility and they also provided valuable information
and data on the Wastewater Plant operations including site energy use, equipment, systems,
and operations.

Based on observations during the assessment, energy conservation opportunities (ECO)
were identified and are summarized in Table 1-1.

Table 1-1: Summary of Energy Conservation Opportunities at the Waimea WWTP

ECO
No.

Recommendation

Potential
Energy
Reduction
( kWh/yr)

Potential
Demand'
Reduction
( kW)

Potential

Water
Reduction
( Gal/yr)

Potential

Cost
Savings
($/yr)

Estimated
Implem.

Cost
($)

Simple
Payback
(Years)

Investment Grade Measures

1

Lighting System
Improvements

9,140

3

0

$2,650

$7,000

2.6

2

Effluent Pumping

System
improvements

8,000

10

0

$2,320

$17,500

7.5

3

Replace Lower
Efficiency Motors
With Higher
Efficiency Motors

9,600

5

0

$2,800

$23,000

8.2

4

Install New Direct
Drive, Higher
Efficiency Blowers
With Automated
Process Controls

34,000-
84,000

>6

0

$9,900-
$24,400

$99,000-
$244,000

10.0

Total Potential
Electrical Energy
Savings

60,740-
110,740
kWh/yr











Total Potential
Electrical Demand
Savings



24 kW









Total Potential Water
Savings





0 Gal/yr







Total Potential Cost
Savings







$17,670-
$32,170
$/yr





Total Estimated
Implementation Cost









$146,000-
$291,500



Total Simple Payback











8.3-9.1

Section 1. Executive Summary

I

[SI

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Energy Assessment Report - County of Kauai, Waimea WWTP

Table 1-1 Notes:

1. Potential Demand Reduction (kW) = Estimated billing demand reduction.

ECO	Energy Conservation Opportunity

kWh/yr	Kilowatt-hours per year

kW	Kilowatts

Gal/yr	Gallons per year

$/yr	Dollars per year

ECO No. 1. Replace current lighting technologies with higher efficiency lighting
technologies.

ECO No. 2. Replace lower efficiency motors with higher efficiency motors in addition to
completing a more detailed assessment of all motors at the plant prior to final equipment
selection and implementation.

ECO No. 3. Convert the constant speed effluent pumping system to a variable flow
pumping system (Variable Frequency Drive "VFD" equipped pump) and modify the
control strategy to allow the smaller horsepower effluent pumps to operate over a wider
range of level.

ECO No. 4. Replace existing constant speed, belt driven, lower efficiency blowers and
motors, and manual controls with new direct drive, higher efficiency blowers and motors,
and automated controls.

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Energy Assessment Report - County of Kauai, Waimea WWTP

TABLE OF CONTENTS

SECTION 1 - Executive Summary	i

Table of Contents	iii

SECTION 2 - Introduction	1

SECTION 3 - Wastewater Treatment Plant Description	2

SECTION 4 - Utility Analysis	7

SECTION 5 - Energy Conservation Opportunities (ECO)	17

ECO-1: Lighting System Improvements	17

ECO-2: Effluent Pumping System Improvements	20

ECO-3: Replace Lower Efficiency Motors With Higher Efficiency Motors	22

ECO-4: Install New Direct Drive, Higher Efficiency Blowers With Automated Process
Controls	26

SECTION 6 - Sustainable Energy Opportunities	29

SECTION 7 - Additional ECO Considerations	31

Table of Contents

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Energy Assessment Report - County of Kauai, Waimea WWTP

SECTION 2
Introduction

In 2009, Congress passed the American Recovery and Reinvestment Act (ARRA) which
contains funding for Environmental Protection Agency (EPA) Region 9 States (AZ, CA, HI,
NV), federally recognized Tribes, and Island Territories (America Samoa, Commonwealth
of the Northern Marianas Islands, Guam) (States) to construct water infrastructure. ARRA
promotes sustainable water infrastructure practices by requiring 20% of the funding to be
directed to energy efficiency, water efficiency, green infrastructure, and/or other innovative
environmental projects through the Green Project Reserve (GPR). GPR projects are
identified on each State's Intended Use Plan, workplan, or Interagency Agreement
developed specifically for the funding received under ARRA.

This report was prepared by Tetra Tech in support of EPA Region 9 Water Division in
implementing the GPR requirements of ARRA. Mr. Donald King and Ms. Kim Williams
conducted the field audits, analyzed site data and drafted the following report under project
manager, Victor D'Amato. The EPA Region 9 provided for the Energy Assessments at four
Wastewater Treatment Plants (WWTP) on the islands of Hawaii. Those sites selected for
evaluation included:

•	Hilo WWTP - located on the island of Hawaii.

•	Kailua WWTP - located on the island of Oahu.

•	Kihei WWTP - located on the island of Maui.

•	Waimea WWTP - located on the island of Kauai.

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Energy Assessment Report - County of Kauai, Waimea WWTP

SECTION 3

Wastewater Treatment Plant Description
Location

The Waimea Wastewater Treatment Plant is located at, 9275 G. Kaumualii Highway,
Waimea, Hawaii. As shown in Figure 3-1, the facility is located on the southwest shore of
the Island of Kauai.

Figure 3-1: WWTP Island Vicinity Map

KAUAI

OAHU

The facility is located just northwest of downtown Waimea on the north side of State
Highway 50. Figure 3-2 provides a vicinity map of the area and the treatment plant
location.

Section 3. Wastewater Treatment Plant Description

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Energy Assessment Report - County of Kauai, Waimea WWTP

Figure 3-2: WWTP Island Vicinity Map

WWTP

Reservoir

The WWTP is comprised of three process areas, including the primary, secondary
treatment, and the solids handling areas. The effluent is disinfected and reused at the
nearby agricultural operations. Back-up effluent disposal is provided at several injection
wells located at the treatment plant. The facility has a waste discharge permit.

The service area sewage is collected and conveyed to the Waimea WWTP via a series of
gravity systems and pump stations. The facility was constructed in 1972-1973.

WWTP Operating Schedule

The plant maintains a staff of approximately 3 full-time operators during the week. Daily
operations typically run between the hours of 7:00 a.m. and 3:30 p.m., Monday through
Friday. The site is also staffed with approximately half the employees loading on one
shift for Saturday and Sunday. Operators are on standby during the evening hours.

WWTP Process

The existing treatment plant has a design capacity of 0.30 million gallons per day (MGD)
with a peak hourly maximum of 0.50 MGD. Currently, the facility is operating at 0.25
MGD. Figure 3-3 provides a schematic of the major treatment processes and plant flow.
Waimea is designed for Conventional Activated Sludge secondary treatment.

Section 3. Wastewater Treatment Plant Description

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Energy Assessment Report - County of Kauai, Waimea WWTP

Figure 3-3: Plant Flow Diagram

Influent Pumping
(Onsite Pump
Station)

Chlorine
Contact Tank

Secondary
Clarifiers

Aerobic
Digester

Sludge Drying Beds
(Solar Drying)

Landfill

The wastewater is pumped to the headworks of the facility from Pump Station A. Pump
Station A is powered from the plant main control panel and is included in the overall
plant electrical load. Currently, the headworks screening and grit removal processes are
out of operations pending construction of the new water reclamation plant.

The flow continues to the course aeration basins. The aeration air is provided by an air
blower room with three constant speed blowers. The aeration air is set manually. Biomass
laden wastewater is conveyed via channel to the final settling clarifiers. The secondary
clarifiers allow a quiescent period of approximately 2-hours for biomass settlement.
Approximately 90% of the biomass is pumped back to the aeration basins as return
activated sludge (RAS) and a small portion, approximately 10% is pumped to the aerobic
digesters as waste activated sludge (WAS).

Secondary effluent flows to the chlorine contact basins for chlorine addition. Disinfected
effluent is pumped to an off-site reservoir and storage.

In the event the effluent pump station fails, or the reclaim water reservoir and distribution
system is at maximum storage capacity, the fail-safe disposal method is via an on-site
injection well.

Solids (WAS) from the secondary clarifiers are pumped to an aerobic digester where
process air is continuously added via aeration blowers (part of the aeration blower
manifold). The agitation/mixing air is provided and the volatile solids reduced prior to
dewatering.

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Energy Assessment Report - County of Kauai, Waimea WWTP

After the sludge has been digested, a stabilized sludge is pumped via engine driven pump
to the solar drying beds. The sludge is dried and sent to the local landfill for disposal.

The facility is equipped with various support systems including: plant air, plant water, an
administration and maintenance building, emergency power, and chemical handling.

The main energy users within the facility are the aeration blower, influent and effluent
pumping.

Footnote:

A new water reclamation facility is in the construction phase and will include a
comprehensive reconstruction and expansion of the treatment plant. In addition, a
photovoltaic (PV) solar energy field is planned for the parcel of land immediately north
of the new treatment plant. The PV system is described farther in Section 7. Also, a
second injection well is planned as part of the expansion project. The anticipated new
treatment plant energy loads are anticipated to increase due to idtraviolet disinfection,
mechanical dewatering, and enhanced treatment processes throughout the new
configuration. All of the existing process tanks will be reused in some capacity.

Table 3-1 provides a summary of major equipment, estimated annual operational hours,
and annual energy usage based on the twelve month period July 2008- June 2009.

As indicated in Table 3-1, the aeration blower, influent and effluent pumps account for
approximately 83% of the energy use by the high energy use equipment.

Table 3-1: Major Equipment Inventory List

(Based on an average 26,050 kilowatts per month(4), 0.25 MGD wastewater,
(Major Equipment is defined as 1 hp or greater)

No.

Equipment Description

Equipment
Size1
(hp)

Equipment
Load2
(kW)

Est. Operational
Hours3
( hrs/yr)

Est. Energy
Usage4
(kWh/yr)

Influent Pump Station Pumps
(PS #A, 2 units))

1 @17.3

630 each

21,800

Sludge Pump #1
(Using Fuel Oil Geni)

7.5

Sludge Drying Bed Underdrain
Pumps (2 units)

1@2.2

100 each

430

Aeration Primary Blower
(1 unit, 100% Operation)

1 @16.5

8,760

144,400

Aeration Primary Blowers (2 units)
(1 unit, 40% Operation)

1 @16.5

1,752 each

57,700

Froth Spray Pump

Effluent Pump

1 @17.2

2,640

45,300

Effluent Pumps (2 units)

1 @3.5

150 each

1,040

Administration / Maintenance
Buildings - Estimated Load

...

3 kW
average

4,380

13,100

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Energy Assessment Report - County of Kauai, Waimea WWTP

No.

Equipment Description

Equipment

Size1
(hp)

Equipment
Load2
(kW)

Est. Operational
Hours3
( hrs/yr)

Est. Energy

Usage4
(kWh/yr)

10

Lighting Load

—

3.9 kW
average

2,900

11,300

11

Balance of Plant Load

—

2 kW
average

8,760

17,520



TOTALS:







312,6005

Notes:

1.	The equipment size includes nameplate horsepower (hp) rating of the equipment.

2.	The equipment load includes measured average amperage readings taken at time of site
on site survey to calculate power in kilo-watts (kW) considering the efficiency rating if
available and operating characteristics.

3.	Hrs/yr is hours per year.

4.	Estimated energy usage (kWh/yr is Kilowatt-hours per year) is based on equipment and
operating conditions. Energy use may not equal the product of the equipment size (kW)
and the operating hours per year (hrs/yr) values shown due to truncating.

5.	The total site estimated energy use captures upwards of 95% or more of annual site
energy use.

Section 3. Wastewater Treatment Plant Description

m

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Energy Assessment Report - County of Kauai, Waimea WWTP

SECTION 4
Utility Analysis

Current Utility Use

The Waimea WWTP currently consumes and is billed for four types of utilities, including
Electricity, Propane, #2 Fuel Oil, and Water. Utility usage data and bills were reviewed
between 2007-2009, or as available. According to this data, the site currently spends a
total of over $103,000 annually for the site's energy and water usages. Over 87 percent of
this cost is from electrical energy use. The use and cost summaries for each of these
utilities are detailed in the sections below.

Table 4-1: WWTP Typical Annual Utilities

Utility

Site Utility Use
(common units)

Site Utility Use
(equivalent units)

Site Utility Costs

% of Costs

Electricity

312,720 kWh

1,067 MMBTU

$90,800

87.6%

Water

3,732,000 gal

$12,500

12%

Propane

12 gal

0.03 MMBTU

$100

0.1%

#2 Fuel Oil

118 gal

17 MMBTU

$200

0.3%

| Total

1,084 MMBTU

$103,600

100%

Propane

Liquefied petroleum gas or propane is used at the WWTP. The propane is delivered to the
site in vertical vessels. The main user of this fuel is the site's water heater which is very
seldom used. Typical annual use is approximately 12 gallons at a cost of approximately
$100 per year.

#2 Fuel Oil /Diesel Fuel

Number 2 fuel oil or diesel fuel is used at the WWTP. The diesel energy is delivered to
the site by truck and offloaded at the site's 1,000 gallon receiving tank. The users of this
fuel at the site include the larger hauling trucks, a diesel generator that provide backup
electrical energy to the site in the event of an electrical power outage and a local diesel
powered pump currently used in replacement of the sites the sludge pump. The actual
plant use is small, as the generator is typically run unloaded for about 0.5 hour weekly
and the sludge volumes are low. Typical annual use is approximately 100 gallons, at a
cost of approximately $200 per year.

Water

Purchased treated water is supplied to the WWTP. The city water is delivered to the site
through a two inch water main supply line. Typical annual use is approximately
3,732,000 gallons, at a cost of approximately $12,500 per year.

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Energy Assessment Report - County of Kauai, Waimea WWTP

Electricity

Kauai Island Utility Cooperative, (KIUC) provides electrical energy to the WWTP. The
electrical energy is delivered through one transformer on site and one meter. Typical
annual use is approximately 313,000 kilo-watt hours, at a cost of approximately $91,000
per year. Table 4-2 provides a summary of the electrical energy use purchased from
KIUC for the Waimea WWTP for the period of October 2008 through September 2009.

Table 4-2: WWTP Monthly Electrical Energy Use

Billing Period

Electrical Energy
Use (kWh)

Electrical Energy
Cost ($)

Oct-08

27,280

$11,728

Nov-08

26,080

$10,299

Dec-08

24,000

$8,110

Jan-09

28,480

$7,650

Feb-09

24,000

$5,751

Mar-09

26,560

$5,951

Apr-09

25,200

$5,780

May-09

28,640

$6,663

Jun-09

25,200

$6,412

J u 1-09

26,480

$7,027

Aug-09

23,760

$6,983

Sep-09

27,040

$8,437

Average (12 months)

26,060

$7,566

Total (12 months)

312,720

$90,790

As shown in Table 4-3 below, approximately 95% of the site's total electrical energy
charges were for electrical energy use charges: 4.5% for electrical energy demand
charges, and the remaining 0.5% for customer charges and other surcharges not impacted
by electrical energy use or demands.

Table 4-3: WWTP Monthly Electrical Energy Cost Influence

Billing
Period

Billing

Days

Electrical Energy
Use Costs ($)

Electrical Energy
Demand Costs ($)

Other

Costs ($)

Total Electric
Costs ($)

Oct-08

32

$11,424

$268

$36

$11,728

Nov-08

30

$9,961

$302

$36

$10,299

Dec-08

27

$7,733

$340

$36

$8,110

Jari-09

33

$7,176

$438

$36

$7,650

Feb-09

28

$5,379

$336

$36

$5,751

Mar-09

30

$5,584

$331

$36

$5,951

Apr-09

29

$5,415

$328

$36

$5,780

May-09

33

$6,298

$328

$36

$6,663

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Energy Assessment Report - County of Kauai, Waimea WWTP

Billing
Period

Billing

Days

Electrical Energy

Use Costs ($)

Electrical Energy
Demand Costs ($)

Other

Costs ($)

Total Electric

Costs ($)

Jun-09

31

$6,047

$328

$36

$6,412

Jul-09

32

$6,662

$328

$36

$7,026

Aug-09

29

$6,618

$328

$36

$6,983

Sep-09

33

$8,072

$328

$36

$8,437

Average (12 months)

$7,197

$332

$36

$7,566

Total (12 months)

$86,369

$3,984

$438

$90,790

Percent of Total

95%

4.5%

0.5%

100%

Table 4-4 provides a breakdown of the monthly measured peak power demands, monthly
billed peak demands, and KIUC demand charges to the Waimea WWTP for the same 12-
month period. As shown in Table 4-4, monthly billed peak demands were generally between
44 and 56 kW. The billed demand is charged at a fixed base rate of $6.08 per month per kW
up to 100 kW. Billing demand for each month shall be the greater of one of the following
two conditions (a) the highest kilowatt demand during the month or (b) 75% of the highest
kilowatt demand during the preceding eleven months, as registered during an interval of
fifteen consecutive minutes by an indicating demand meter. As Table 4-4 indicates, demand
for the months of October 2008 through March 2009 were billed for the prior case (a) and
demand for the months of April through September 2009 were billed for the latter case (b)
due to the abnormal peak established in January 2009 of 72 kW. This means that a prior
monthly demand resulted in an inflated current demand charge for all of the months in 2009
as they were all within an 11-month period after the January peak that caused this increase.
As stated above, the highest maximum peak demand recorded in the last 12 months was in
January 2009 at 72 kW. The lowest maximum peak demand was in October 2008 at 44 kW.

Table 4-4: WWTP Electrical Power Demand Summary

Bill Period

Measured Peak
Demand (kW)

Billed Peak
Demand (kW)

Total Demand
Charge ($)

Oct-08

44.00

44.00

$268

Nov-08

49.60

49.60

$302

Dec-08

56.00

56.00

$340

Jan-09

72.00

72.00

$438

Feb-09

55.20

55.20

$336

Mar-09

54.40

54.40

$331

Apr-09

49.60

54.00

$328

May-09

48.80

54.00

$328

Jun-09

51.20

54.00

$328

Ju!-09

47.12

54.00

$328

Aug-09

47.12

54.00

$328

Sep-09

46.64

54.00

$328

Average

52

55

$332

Total

n/a

n/a

$3,984

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Energy Assessment Report - County of Kauai, Waimea WWTP

Note: Total demand charges above represents the base effective demand rate only as defined
in the utility schedule.

Below Figure 4-1 provides a trend of the plant's electrical demand energy during a recent
week in January 2010. This interval demand information was recorded by a temporary
electric meter brought to the site by KIUC. The sites peak demands are stored within the
local KIUC electric meter, however the interval data histoiy is not, since the meter pulse
data is not connected to KIUC's central database. Typically, if the meter is connected,
this recorded information can be gathered from the utility provider, or remote access to
an online interface may be available to view the information on a regular basis.

Figure 4-1: WWTP Electrical Energy - 15 Minute Interval Demand Trend
rs6

o I

16 Sat 17 Son 18Mon 19 Tu« 20 Wed 21 TTiu 22Frt

Jan 2010

• < il Aiiiim S 1 I*

¦ flagga i i¦ Hi

A plant's electrical demand typically follows the influent flow volumes; as influent flow
increases, so does the amount of equipment online and hence, an increase in electrical
energy use. Since the plant is typically staffed during the day only, the demand energy for
the site is elevated slightly during the day versus at night. This can be seen on the demand
trend above in which daily operations rise to a level of approximately 35-40 kW during the
day and drop to approximately 28 kW during the evening periods. Also notice that the plant
measured peak demands, which are typically over 50 kW, did not occur during this week of
metering. In evaluating one minute demand trends that were taken in April 2009, demand
levels at or above 45 kW typically only occur about once per month or very infrequently.
Table 3-1 in Section 3 shows that it would only take one influent pump, one blower and one
large effluent pump to be in operation at the same time to pull over 50 kW of demand at the
site. This would occur in the case of higher than normal flows or when a more constant
influent flow to the plant is observed. Unfortunately no instantaneous meter data is readily
available to confirm this correlation of peak demand with peak and/or constant influent
flow. If either of these situations can be controlled, then the site could better manage this

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Energy Assessment Report - County of Kauai, Waimea WWTP

portion of the bill. Fortunately, the new plant design has incorporated an equalization basin
at the entrance to the plant, and this may assist in curbing such influxes in flow and
equipment demand in the future.

As shown in Figure 4-1 above, this information can provide instantaneous awareness and
feedback to the site about how much energy the plant equipment is using. The site can then
determine how changes at the operations level impact the sites demand and make decisions
accordingly. This can be valuable information if trying to control measured demands. Since
approximately 4.5% of the site's electrical costs are determined from the monthly peak 15-
minute interval demand, the site has direct influence over this portion of the bill, but at this
time it would not influence the overall electric costs by much. However, as the new plant is
built and the sites peak electric demands increase above lOOkW, they are likely to move to a
different rate schedule with KIUC. A new rate schedule will likely increase demand costs
and move this 4.5% to a higher percentage of the bill. The new PV system will provide
some additional support to assist in curbing the new anticipated electric demands and use at
the plant. However it may not prevent a change in the rate schedule. Careful coordination
between plant demands and time of day use for such demands will be key to keeping off the
higher cost rate schedule and to keep such additional costs in line as much as possible. More
details of the current billing rates are discussed in the following section of the report.

Electricity Rate Schedule

The Waimea WWTP purchases electricity from KIUC and is under the KIUC Electric
Tariff Schedule "J" for General Light and Power Service. Schedule "J" is applicable for
general light and/or power supplied through a single meter in which the customer's
energy consumption exceeds 10,000 kWh or exceeds 30 kW and whose maximum
demand is not greater than 100 kW during any consecutive 15-minute period.

The sites actual electric bills were not provided; therefore a full breakdown of the sites
electrical energy charges was not calculated. As shown in Table 4-2, the sites electrical
consumption for the more recent 12 month period captured from the site is 312,720 kilo-
watt hours at a cost of $90,790 yielding an average "all inclusive" electric rate of
$0.290/kWh. This average electric rate was utilized for estimating cost impacts of the
Energy Conservation Opportunities in Section 5.

Table 4-5 describes the rates calculated from the WWTP's electric energy billed costs for
the 12-month period starting October 2008 through September 2009.

Table 4-5: WWTP Monthly Electrical Energy Use and Demand Rates Utilized for

ECO Cost Impact for the Site

Billing Billing
Period Days

Electrical Energy
Use & Costs

Electrical Energy
Demand Use & Costs

Other
Costs ($)

Total Electric
Use & Costs

Total (12 months)

$90,790 /yr

n/a

$90,790 /yr

Total (12 months)

312,720 kWh/yr

55 kW/mo average

n/a

Rate Used for ECO
Calculations

$0,290 /kWh

n/a

Section 4. Utility Analysis

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Energy Assessment Report - County of Kauai, Waimea WWTP

The site's electric service rate schedule is broken down into the following charges as of the
date of this report:

•	Customer Charge - this is a fixed fee of $36.48 per month and does not vary with
use.

•	Energy Charge - this is a fixed fee with a base rate of $0.16031 per kilowatt-hour.

•	Demand Charge - the monthly billing demand shall be the greater of (a) the
highest kilowatt demand during the month or (b) 75% of the highest kilowatt
demand during the preceding eleven months, as registered during an interval of
fifteen consecutive minutes by an indicating demand meter. Like the customer and
energy charge, this is also a fixed fee at $6.08 per month per kW of billing demand.

•	Resource Cost Adjustment (DSM & IRP) Surcharge - a surcharge that is to be
added to the Customer and Energy, and energy cost adjustment. For October-
December 2008 this rate was $0.003534. For 2009 this rate was $0.000888.

•	Energy Rate Adjustment - this factor is evaluated each month and is charged to the
energy used in kWhs. If the PUC approves KIUC's submitted rate change, then the
new rate takes effect from that day forward until a new rate is approved. Since 2001,
this rate has typically changed monthly. The days in the billing period are charged at
the respective rates for such charges. In 2008, this rate increased to over $0,316 per
kWh. In 2009, this rate averaged approximately $0,264 per kWh.

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Energy Assessment Report - County of Kauai, Waimea WWTP

Energy Baseline

The following Figure 4-2 describes the site's energy use over the 12-month period from
October 2008 through September 2009.

Figure 4-2: WWTP Total Energy Use Breakdown

110

Months

E2 Electricity ¦ Propane ~ #2 Fuel Oil

Section 4. Utility Analysis

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Energy Assessment Report - County of Kauai, Waimea WWTP

The following Figure 4-3 describes the site's energy costs over the same 12-month
period, from October 2008 through September 2009. This illustration provides a view of
the changes over time of the utility rates (specifically electrical rates) from 2008 to 2009,
as oil prices in the world and region decreased significantly over the time period.

Figure 4-3: WWTP Total Energy (and Water) Cost Breakdown

$13,000
$12,000
$11,000
ZZ $10,000

to


O

u

$9,000 j j I	1 I	I

$8,000
$7,000
$6,000
$5,000



i





















m

wm.

c<

& ^

<§> &

& &
<$> ^

&

&

Months





JSr SP
c<£

0 Electric ~ Water ~ Propane ~ Fuel Oil

Section 4. Utility Analysis

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Energy Assessment Report - County of Kauai, Waimea WWTP

The following Figure 4-4 describes the site's electrical energy costs over the same 12-
month period from October 2008 through September 2009. This illustration provides a
breakdown of electric use costs versus electric demand costs. The site demand costs are
on average approximately 4.5% of the electric bill each month.

Figure 4-4: WWTP Electric Energy Cost Breakdown

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Section 4. Utility Analysis

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Energy Assessment Report - County of Kauai, Waimea WWTP

Since the site major utility use is electric energy, the following Figure 4-5 illustrates an
overall energy baseline for electric energy use per million gallons of wastewater treated
for the 12-month period from October 2008 through September 2009. This provides one
productivity measurement of an energy utilization index to demonstrate deviations in
electrical energy use over time. This offers both advantages and disadvantages in
comparing year-to-year energy efficiency improvements and should not be used as a sole
source of comparison.

Figure 4-5: WWTP Electric Energy Use Per Million Gallons of Wastewater Treated

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Energy Assessment Report - County of Kauai, Waimea WWTP

SECTION 5

Energy Conservation Opportunities

ECO 1 - Lighting System Improvements

Recommendation

It is recommended that the Waimea WWTP considers further investment in new higher
efficiency lighting technologies to reduce the site's electric demand and use. Replacing
lower efficiency lighting systems with higher efficiency lighting systems will standardize
lamp and ballast types and reduce the number of lamps, ballasts and other lighting
equipment to be stocked and managed. Fixture upgrades would include replacing all T12
fluorescent lamps with T8 fluorescent lamps. Also, it is recommended to replace
magnetic ballasts with electronic ballasts for further energy load improvement of the
fixtures. Other fixture upgrades include considering replacement of HID fixtures with
LEDs for improved control and to significantly reduce maintenance costs. Lighting
controls are also recommended to optimize on lamp energy use and extend lamp life.
Estimated energy, power demand, and cost savings and simple payback from such
installations are summarized below.

Background

It was observed that a total of approximately 45 interior and exterior fixtures at the site
use older generation lighting technologies. Most of theses fixtures were installed when
the building or area was erected. This older lighting technology includes T12 fluorescent,
incandescent, and High Pressure Sodium lamps and fixtures which also use magnetic
ballasts.

The interior building lighting systems are typically on during daily operations. During the
evening hours when the site is unoccupied the interior building lighting systems are shut
down. The current controls for these fixtures are manual switches. The exterior lighting
systems are also controlled manually and only turned on when necessary. It was
estimated site exterior lighting is used approximately 200 hours per year.

Not including the cost of maintenance and replacement lamps and ballasts, it was
estimated that the Waimea WWTP is spending over $3,000 per year for the energy to
light areas of the plant. This estimate is based on light counts and information collected
during the site walk.

Estimated Electrical Energy Savings
Estimated Electrical Demand Savings

9,140 kWh/yr
3 kW

Estimated Total Energy Cost Savings
Estimated Implementation Cost
Simple Payback

= $2,650/yr
= $7,000
= 2.6 years

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Energy Assessment Report - County of Kauai, Waimea WWTP

Many of these lighting systems can be replaced with more efficient i.e. lower wattage
lamps and ballasts. While replacing the lamps is a short term solution, Light Emitting
Diodes (LED) is an example of a longer term solution. For instance LED lamps are rated
for approximately 100,000 hours while high pressure sodium (HPS) lamps currently used
by the site are rated for just a fraction of this lamp life at 24,000 hours approximately.
The initial cost of LED maybe higher than HPS lamps, yet they consume minimal energy
and require less equipment and maintenance which assists in justifying the use of LED. It
is recommended that the site consider such alternative technologies when ultimately
deciding on new fixture replacement.

Control improvements recommended include motion sensors or timer based switches for
the building interior lighting systems. Implementing such controls to interior areas of the
plant would need further assessment and may positively impact the energy reduction of
this ECO.

Estimated Energy and Cost Savings

The estimated electrical demand energy savings, if all fixtures and lamps were replaced
with higher efficiency ballasts and lamps, and operating at the same current conditions, is
3 kW. Based on the current operating hours for lighting, the energy savings would be
9,140 kWh per year.

The total estimated annual Cost Savings (CS) is the sum of the Electrical Energy Cost
Savings (ECS) and Demand Cost Savings (DCS). The electrical energy and demand
charges are based on the KIUC 2008-09 data as presented in Section 4.

CS = (ECS)(Usage Charge) + (DCS)(Demand Charge)

CS = (9,140kWh/yr) X 0.29 ($/kWh)] + [3 (kW) X 0 ($/kW-month) X 12

(months/yr)]

CS = $2,650/yr + $0/yr
CS = $2,650/yr

Estimated Implementation Cost and Payback

The total preliminary estimated cost to implement this ECO is $7,000. This estimate
includes the cost for new lighting fixtures, ballasts, lamps and installation.

Based on this preliminary assessment, the simple payback period would be 2.6 years.

The following assumptions were made about this ECO:

1)	Lamps and fixture prices remain the same.

2)	Light counts are estimates.

3)	Interior lighting operates on average 8 hours per day, 7 days per week.

4)	Exterior lighting operates on average 200 hours per year.

5)	Reduced lamp replacement costs (equipment and labor) due to extended lamp life
expectancies for new lighting technologies were not included in the savings
estimates.

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Energy Assessment Report - County of Kauai, Waimea WWTP

6) Cost savings estimated were based on current electric demand rates and cost
adjustment factors. Future rates for the site may go up or down and would impact
the cost savings estimates in this ECO accordingly.

The following steps are required to implement this ECO:

1)	Further evaluation with regard to the new plant design is necessary for full
implementation of this ECO for future facility needs.

2)	Confirm lighting fixture, efficiency, and operating hours.

3)	Confirm lighting levels and acceptability of new fixture types and controls.

4)	If the ECO has acceptable operational criteria and an acceptable payback period,
implement the ECO.

Plant Staffing Impact

Implementation of this ECO is not anticipated to impact plant staffing or operating
requirements.

Photo Gallery









Existing Outdoor Lighting



Section 5. Energy Conservation Opportunities (ECO)

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Energy Assessment Report - County of Kauai, Waimea WWTP

ECO 2 - Effluent Pumping System Improvements

Recommendation

It is recommended that the Waimea WWTP considers equipping the effluent pumps with
variable frequency drives (VFD's) and adjusting the level control range at which the
pumps operate. This retrofit will reduce the site's electric demand, improve operating
efficiencies and be consistent with the new treatment plant's flow equalization basin
strategy. The variable speed pumps and wider control range would allow the smaller
pumps to operate and minimize the use of the larger horsepower effluent pump.
Estimated energy, power demand, and cost savings and simple payback from installations
identified during the initial audit only are summarized below.

Background

Currently the WWTP utilizes one 25 horsepower (hp) and two 5hp constant speed pumps
for effluent pumping needs at the site. The pumps are controlled by a liquid level sensor
in the effluent channel. Since the influent into the plant is provided by constant speed
pumps, the effluent liquid level modulates (rises and falls) based upon the short term
(pulse) type operations. The effluent pump(s) operate in concert with the influent
pumping and results in a double demand spike (one spike for the influent pumps and a
second spike for the 25 hp effluent pump.)

A new plant is currently under design and plans to reuse the effluent pump station. The
VFD control modifications recommended here will be consistent with the new plant
design requirements.

Estimated Energy and Cost Savings

The current electrical energy used by the effluent pump station is approximately 46,300
kwh per year with a demand load of approximately 20 kW. The effluent VFD and control
strategies will reduce the peak demand and have a slight reduction in operating kilowatt-
hours.

The total estimated annual Cost Savings (CS) is the sum of the Electrical Energy Cost
Savings (ECS) and Demand Cost Savings (DCS). The electrical energy and demand
charges are based on the KIUC 2008-09 data as presented in Section 4.

CS = (ECS)(Usage Charge) + (DCS)(Demand Charge)

CS = [8,000 (kWh/yr) X 0.29 ($/kWh)] + [0 (kW) X 0 ($/kW-month) X 12

(months/yr)]

CS = $2,320/yr + $0/yr

0

Estimated Electrical Energy Savings
Estimated Electrical Demand Savings

8,000 kWh/yr
10 kW

Estimated Total Energy Cost Savings
Estimated Implementation Cost
Simple Payback

= $2,320/yr
= $17,500
= 7.5 years

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Energy Assessment Report - County of Kauai, Waimea WWTP

Estimated Implementation Cost and Payback

Prior to implementation of the effluent pump VDF and level control retrofit, the site will
need to further evaluate the future plant designs that are currently under development.
This ECO was developed for providing only a perspective here for the plant on what
improvements such as these could potentially have on the plant operations based on what
information is known today.

Based on this preliminary assessment, a retrofit cost of $17,500 was estimated for the
addition of a new VFD drive to the 25 hp motor and liquid level control adjustments.

The following assumptions were made about this ECO:

1)	Future variable speed load factor was estimated at 50%.

2)	Cost savings estimated were based on current electric demand rates and cost
adjustment factors. Future rates for the site may go up or down and would
impact the cost savings estimates in this ECO accordingly.

The following steps are required to implement this ECO:

1) Further evaluation with regard to the new plant design is necessary for full
implementation of this ECO for future process needs.

Plant Staffing Impact

Implementation of this ECO is not anticipated to impact plant staffing or operating
requirements.

Photo Gallery

Existing 25 hp and 5 hp Effluent Pumps

Section 5. Energy Conservation Opportunities (ECO)

S

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Energy Assessment Report - County of Kauai, Waimea WWTP

ECO 3 - Replace Lower Efficiency Motors With Higher Efficiency Motors

Recommendation

It is recommended that the Waimea WWTP considers investment in new higher
efficiency motors, to reduce the site's electric demand and improve operating efficiencies
of motorized systems throughout the facility. Estimated energy, power demand, and cost
savings and simple payback from installations identified during the initial audit only are
summarized below.

Estimated Electrical Energy Savings	= 9,600 kWh/yr

Estimated Electrical Demand Savings = 5 kW

Estimated Total Energy Cost Savings = $2,800/yr
Estimated Implementation Cost	= $23,000

Simple Payback	= 8.2 years

Background

Many systems throughout the WWTP utilize electrical motors for operation of blowers,
pumps, fans, compressors, and other operations such as skimmer mechanisms, etc.
Motorized equipment uses the majority of the site's electrical use. There are over 15
motors at the site with the majority of these motors over 1 horsepower in size or greater.
Higher-efficiency or premium efficiency motors are typically available in motors of 1
horsepower and larger.

Many of the motors on site were installed in 1974 when the plant was built and are low
efficiency rated units. Many units are still operation at the site even though the plant is
over 36 years old. Efficiency ratings of motors found at the site were typically in the low
80% level. With the site's current electrical energy costs, it has been determined that
motors operating continuously or 8,760 hours per year with an existing efficiency of
below 93% and operating load factor of at least 80% would most likely meet a 10-year
simple payback if replaced with a higher efficiency motor. Motors in use at least half the
year or approximately 4,380 hours per year with an existing efficiency below 92% and
operating load factor of at least 80% would also likely meet a 10-year simple payback.
The following list of motors in Table 5-1 below were identified for replacement to higher
efficiency type units.

Table 5-1 Motor Upgrade List

Motor/System Description

Number of
Motors

Motor
Horsepower

Current
Efficiency

Influent Pump Station Pumps

2

25

82.5%

Effluent Pump (Large Unit)

1

25

82.5%

Effluent Pumps (Small Units)

2

5

82.5%

Sludge Scrapper

1

0.5

82.5%

Scum Collectors

2

0.5

82.5%

Total

8

87

—

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Energy Assessment Report - County of Kauai, Waimea WWTP

Note that current new plant design specifications are calling for all of the above motors to
be replaced with the new plant installation except for the 3 effluent pumps. If this
specification should change prior to or during construction of the new facilities, the plant
should revisit what motors are not replaced at that point for replacement.

Estimated Energy and Cost Savings

The estimated electrical demand energy savings, if all motors in Table 5-1 were replaced
with the higher efficiency motors and operating at the same current conditions, is 5 kW.
Based on the current operating hours for each motor, the energy savings are estimated at
9,600 kWh per year.

The total estimated annual Cost Savings (CS) is the sum of the Electrical Energy Cost
Savings (ECS) and Demand Cost Savings (DCS). The electrical energy and demand
charges are based on the HELCO 2008-09 data as presented in Section 4.

CS = (ECS)(Usage Charge) + (DCS)(Demand Charge)

CS = [9,600 (kWh/yr) X 0.29 ($/kWh)] + [5 (kW) X 0 ($/kW-month) X 12
(months/yr)]

CS =$2,800/yr + $0/yr

CS = $2,800/yr

Estimated Implementation Cost and Payback

The total preliminary estimated cost to implement this ECO is $23,000. This estimate
includes the cost for the new motor equipment and installation.

Based on this preliminary assessment, the simple payback period would be 8.2 years.

The following assumptions were made about this ECO:

1) The motors identified in Table 5-1 were electrically metered for load factor
values and therefore unit load is based on site operating conditions measured.

2) Some motors identified in Table 5-1 had nameplate data that was not captured
due to nameplate missing, unrecognizable text on nameplate and/or
information not available from site equipment manuals or other means. In
these instances unit information was estimated based on year equipment was
purchased.

3) Influent pump station pumps were built in 1974 and are due to be replaced in
the plans for a new plant. These units individually do not meet a 10 year
simple payback threshold, but when paired with the other motor replacements
the collective ECO does still meet such a threshold. We recommend the site
further evaluates replacement of these units with greater than 94% efficiency
motors that are available in the market today.

3) Improvements for blower motor replacement were captured in ECO #4.

4) Cost savings estimated were based on current electric demand rates and cost
adjustment factors. Future rates for the site may go up or down and would
impact the cost savings estimates in this ECO accordingly.

Section 5. Energy Conservation Opportunities (ECO)

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Energy Assessment Report - County of Kauai, Waimea WWTP

The following steps are required to implement this ECO:

1)	Further evaluation with regard to the new plant design is necessary for full
implementation of this ECO for future process needs.

2)	Confirm equipment size, efficiency, and operating hours.

3)	Confirm equipment rpms, loading, and horsepower requirements.

4)	Add motor performance evaluation to site PM process for future selection of
motors that meet criteria for replacement, as site conditions change.

Plant Staffing Impact

Implementation of this ECO is not anticipated to impact plant staffing or operating
requirements.

Photo Gallery

Existing Effluent Pumps and Motors

Existing 25hp Effluent Pump Motor Nameplate

Section 5. Energy Conservation Opportunities (ECO)

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Energy Assessment Report - County of Kauai, Waimea WWTP

Section 5. Energy Conservation Opportunities (ECO)

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Energy Assessment Report - County of Kauai, Waimea WWTP

ECO 4 - Install New Direct Drive. Higher Efficiency Blowers With
Automated Process Controls

Recommendation

It is recommended that the Waimea WWTP considers replacement of the three constant
speed blowers with new higher efficiency variable speed blowers. This retrofit will
reduce the site's electric demand and improve operating efficiencies. The variable speed
blowers would also provide improved aeration or air flow capability and allow for the site
to more efficiently and effectively match dissolved oxygen (DO) supply with DO
requirements of the aeration tanks. Estimated energy, power demand, and cost savings
and simple payback from installations identified during the initial audit only are
summarized below.

Background

Currently the WWTP utilizes three 25 horsepower (hp) constant speed, belt driven
blower units. All three units are rated for 550 cubic feet per minute (cfm) at 6 pounds-
force per square inch gauge (psig) for a total site capacity of 1,650 psig. One unit is fairly
new and was installed approximately 3 years ago while the other two are older units.
Currently the plant is providing air to the secondary aeration basins with coarse bubble
diffusers only. Air piping is installed to provide flow to the headworks and primary
channel; however this air supply flow is not currently in use. For current air needs to the
aeration basins only, the site typically requires one blower online continuously with
partial use for a second blower. The aeration air is currently controlled manually.

A new plant to replace the existing units is currently under design. According to current
design specifications, the site plans to replace all three blower units.

The blower units at 25hp each are three of six largest motors at the site. Also, these units
are operated more than any other motor at the site and are estimated at using over 65% of
the sites electrical energy needs. Due to the large impact these units have on the sites
energy requirements; a thorough evaluation and investigation of the type of units that will
replace the older blowers with the new plant is recommended to verify the most efficient
blowers and aeration system is being specified. It is also recommended the site further
assesses utilization of belt driven units which have lower drive efficiency than direct
drive units in the market today. Direct drive units typically can have drive efficiencies of
97% or more while belt driven drives tend to have only 92-94% drive efficiencies at best
which can deteriorate by 2-5% over time.

Estimated Electrical Energy Savings
Estimated Electrical Demand Savings

34,000-84,000 kWh/yr
>6 kW

Estimated Total Energy Cost Savings
Estimated Implementation Cost
Simple Payback

= $9,900-$24,400/yr
= $99,000-$244,000/yr
= 10.0 years

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Energy Assessment Report - County of Kauai, Waimea WWTP

Estimated Energy and Cost Savings

The current electrical energy used by the blowers in place today is estimated at
approximately 200,000 kWh annually. If all blowers are replaced with higher efficiency
motors and drives and operating at the same current load and flow conditions, we would
anticipate a demand reduction of at least 3 kW when one unit is in operation and an
energy use reduction of up to 34,000 kWh per year. This is a net reduction of at least 17%
without reducing air flow over time. From the site flow conditions it is anticipated to
potentially further reduce the sites energy use for aeration air flow by an additional 15-
25% annually with installation of variable speed units and automated control. Based on
the current operating hours for each unit, the total energy savings the site potentially
would benefit from with improvements to the aeration system is upwards of a 42% total
reduction in aeration energy which equates to upwards of 84,000 kWh per year.

CS = (ECS)(Usage Charge) + (DCS)(Demand Charge)

CS = [34,000-84,000 (kWh/yr) X 0.29 ($/kWh)] + [0 (kW) X 0 ($/kW-month)

X 12 (months/yr)]

CS = $9,900-$24,400/yr + $0/yr
CS = $9,900-$24,400/yr

Estimated Implementation Cost and Payback

Prior to implementation of new blower units, motors and controls, the site will need to
further evaluate the future plant designs that are being developed. This ECO was
developed for providing only a perspective for the plant on what improvements such as
these could potentially have on plant operations based on what information is known
today.

Based on this preliminary assessment, the amount of potential capital funding that would
be supported by such improvements and that meet a 10 year simple payback period is
between $99,000-$244,000.

The following assumptions were made about this ECO:

1) Motor efficiency improvements captured here were not duplicated in ECO #3.

2) Current motor efficiency was assumed to be 82.5%.

3) Current belt driven unit drive efficiency was estimated to be 92% and future
direct drive efficiency was estimated to be 97%.

4) Current/future operating hours were estimated at 100% or 8,760 hrs/year for
one unit and at 40% or 3,504 hrs/year for a second unit.

5) Current/future load factors were estimated at 67% per electrical motor
amperage measurements taken at time of site visit.

6) Future variable speed load factor was estimated at 50%.

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Energy Assessment Report - County of Kauai, Waimea WWTP

7) Cost savings estimated were based on current electric demand rates and cost
adjustment factors. Future rates for the site may go up or down and would
impact the cost savings estimates in this ECO accordingly.

The following steps are required to implement this ECO:

1) Further evaluation with regard to the new plant design is necessary for full
implementation of this ECO for future process needs.

Plant Staffing Impact

Implementation of this ECO is not anticipated to impact plant staffing or operating

requirements.

Photo Gallery

Section 5. Energy Conservation Opportunities (ECO)

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Energy Assessment Report - County of Kauai, Waimea WWTP

SECTION 6

Sustainable Energy Opportunities

An evaluation, of sustainable design concepts, was performed to identify opportunities for
incorporating innovative initiatives such as renewable energy alternatives at the Waimea
Wastewater Treatment Plant. The following table lists the sustainable design options
evaluated at this facility for energy use impact and/or the opportunity to improve the site's
environmental impact. Recommendations are provided for those options the site should
consider for further feasibility.

Section 6. Sustainable Energy Opportunities

-------
Table 6-1 Sustainable Energy Opportunities

SUSTAINABLE

RECOMMENDED NEXT

OPPORTUNITY

DESCRIPTION

STEPS

PAYBACK

Behavioral
Modifications

Facility personnel practices have the potential to impact energy use significantly. Manual
procedures or use of automated controls to lower conditioned air settings when an area is
vacant and turning off lights and equipment when not needed or in use will result in increased
energy savings at all levels of the facility.

Requires Further Study

Short Term

Green Procurement

Environmentally responsible or 'green' procurement is the selection of products and services
that minimize environmental impacts. It requires an organization to carry out an assessment of
the environmental consequences of a product at all the various stages of its lifecycle. This
means considering the costs of securing raw materials, and manufacturing, transporting,
storing, handling, using and disposing of the product. Opportunities at the WWTP may include
the purchase of energy efficient IT systems such as energy star rated computers and
appliances. The purchase of green products for cleaning and IT equipment typically do not cost
more than alternative products.

Requires further study

Short Term

Plant Vehicle Fuel
Options

The plant currently utilizes multiple vehicles for transportation and maintenance purposes. As
vehicles are due to be replaced the site should consider use of hybrid or alternative fuel

Requires further study

Short to Mid
Term

models. An alternative fuel vehicle could also be considered when deciding on new vehicle
purchases.

Solar Renewable
Energy

Waimea is located on the sunny and dry side of the island. A solar to energy facility is
expected to be constructed adjacent to the new plant and an electrical interface is planned.

Currently being constructed

Long Term

Wind Renewable
Energy

Resource is unknown.

Unlikely a good fit for area
adjacent to treatment plant

Long Term

Effluent Water
Reuse

The facility currently reuses effluent for agriculture nearby. The new treatment plant will
enhance the effluent treatment and continue to provide a reliable source of water.

Currently implemented

n/a

Cogeneration

The site operates an aerobic digester for sludge stabilization.

No available resource

n/a

Payback Range Estimate: Short Term = <5 years; Mid Term = 5 years to 10 years; Long Term = > 10 years

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Energy Assessment Report - County of Kauai, Waimea WWTP

SECTION 7

Additional Energy Conservation Considerations

During the course of the site visit and in review of the planned wastewater treatment
plant expansion, a review of the proposed upgrades was conducted which identified
additional avoided energy and cost savings related to resource conservation. While Tetra
Tech was unable to detail these opportunities within the limits of this initial study, these
items warrant further attention, whether requiring additional study or simply operations
and maintenance actions. Table 7-1 lists the opportunities noted and explains the nature
of actions required to capitalize on the items listed.

Section 7. Additional ECO Considerations

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Table 7-1 Additional Energy Conservation Considerations

ECO
OPPORTUNITY

ECO DESCRIPTION

RECOMMENDED
NEXT STEPS

PAYBACK

Energy Tracking

Tracking and trending the site's energy and water use and demands enhances the site's capabilities;
not only to verify energy reduction strategies implemented, but, also to support sustaining these
reductions year after year. This can be accomplished through manual spreadsheets and calculations
or automatically through the site's SCADA system. This information is critical for supporting decisions
from daily operations to future capital investments.

Incorporate energy
management system
within new treatment
plant design.

Short Term

New Treatment
Plant Process
Review and
Recommendations

In review of the proposed design/build treatment plant documents, the following observations are
provided:

• The influent pumps will be replaced with new larger constant speed pumps and maintain the
draw/fill control strategy.

• New process air blowers will be installed to provide aeration air for the aerobic digesters, flow
equalization basins and conveyance channels. [Add process controls and turndown
capabilities.]

• A vortex grit system is being provided in lieu of aerated grit system. [Less air required]

• MBBR process has the lowest energy footprint when compared to convention activated sludge
or MBR.

• UV disinfection was selected over chlorine addition. The specification for the UV indicates
high efficiency, self cleaning and automatic turn-down controller. [Fine tune controller to
maintain proper UV electrical dose.]

• A flow equalization basin (FEB) strategy will be used to dampen the wide swings in flow. The
FEB will be equipped with agitation air to maintain solids suspension and aerobic conditions.
[Recommend careful review of process control for recovery cycle to minimize double
pumping of wastewater.]

• With the use of the FEB strategy, the two 5 hp effluent pumps will be the major effluent
pumping units instead of the 25 hp pump. [Replace motors to premium efficiency.]

• Mechanical dewatering using a centrifuge is planned for operation 6 hours per day, 3 to 4
days per week. The anticipated connected horsepower of 55hp is estimated. The full load
electrical impact will be in the 40 kW demand range. Concurrent operations with high
electrical loads will push the facility into the >100 kW demand schedule and the resulting
additional costs associated with a large electrical user. [Evaluate best time of day strategy
for dewatering operations.]

See highlights to left in
BOLD for individual
recommended next
steps.

Short Term

-------
RECOMMENDED

ECO DESCRIPTION NEXT STEPS PAYBACK

• The new administration/ laboratory building is being equipped with energy efficient lighting and
associated occupancy controls.

• A 137.7kW DC photovoltaic facility is planned to be installed adjacent to the treatment plant to
offset power purchases at the new plant. According to the manufacturer's brochure
(www.recgroup.com/usa) and conceptual design documents the array is anticipated to consist
of 612 REC AE-US 225 Watt DC polycrystalline modules on a REC solar racing rack system
at a fixed tilt. Electrical power generation of the PV system at a 10° tilt angle, 200° azimuth
and 82% DC to AC derate factor is estimated at 112.9kW AC and 203,077 kilowatt hours per
year (65% of current plant electric use). The system is designed for up to a maximum of
112lbs/ft2 load and 122 mph wind speeds. The arrays are 17.76 square feet per module and
with 612 modules will be approximately 11,000 square feet in area. Total cost for the system is
estimated at $799,194 or about $7.08/kW. At the current average electric rate $0.29/kWh and
if 100% of the PV electrical generation is utilized, then the system would reduce site electric
costs by an estimated $58,892/year providing an overall project simple payback of 13.5 years.
This does not include rate schedule impacts or escalation of such rates over time. [The plant
power trend and PV generation trend may be different and seasonal. KIUC will provide
grid stability and any additional power to support the plant operations. Careful
coordination should be made for grid interconnection such as utility bill schedule
impact, standby charge implications and possible sequencing of plant operations to
maximize the generated power during the peak daytime generation. For instance,
dewater sludge during peak solar generation periods. It is anticipated that periods of
excess PV production will occur and the mechanism for handling the excess is
currently under review. If a net metering contract and/or battery capacity can not be
installed, then the size of the system should be further evaluated so that either excess
power generated would be utilized or all power generated would be fully utilized by the
new facility. The new plant and PV design is still preliminary. Once the final designs are
more complete then the power production and utilization of the 203,077 kilowatt hour
electric production can be validated.]

Payback Range Estimate: Short Term = <5 years; Mid Term = 5 years to 10 years; Long Term = > 10 year

ECO
OPPORTUNITY

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10306 Eaton Place Suite 340 | Fairfax, VA 22030

www.tetratech.com

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