Status of ASR in Florida....& Beyond...

Presented at the Presented at the

Presented byPresented by

Mark B. McNeal, P.G.Mark B. McNeal, P.G.

January 24th, 2003January 24th, 2003

Emerging Issues Facing Emerging Issues Facing Water ReuseWater ReuseSponsored bySponsored by

Florida Water Environment AssociationFlorida Water Environment Association

In association withIn association withFlorida Department of Environmental ProtectionFlorida Department of Environmental ProtectionWateReuse AssociationWateReuse Association

Coronado Springs ResortCoronado Springs ResortLake Buena Vista, FloridaLake Buena Vista, Florida

Today’s Presentation

• Introduction• ASR Feasibility• Technical Issues• Summary

PotentialSupply Deficit

PotentialExcess Supply

Mature reuse systems face supply and demand imbalances

Jan Feb March April May June July Aug Sept Oct Nov Dec

Incr

easi

ng D

eman

d

Reclaimed WaterDemand

ReclaimedWater Supply

Many storage options are available

ASR Wells

Surface Reservoirs

?????Above Ground Storage Tanks

Problem: 600 MG storage needed Problem: 600 MG storage needed Problem: 600 MG storage needed

6 ASR Wells6 ASR Wells•$5 to 6 million cost•3 acres of land•$5 to 6 million cost•3 acres of land

120 - 5MGStorage Tanks120 - 5MGStorage Tanks•>$100 million cost•100s of acres of land•>$100 million cost•100s of acres of land

ASR is most feasible in many cases

ASR Technology• Aquifer Storage Recovery, or ASR, is

the seasonal storage of large volumes of potable or non-potable water in a suitable aquifer during periods of low demand, for subsequent recovery during periods of high demand for beneficial use

• Reclaimed Water ASR is the seasonal storage of high quality reclaimed water

DC

ASR is a proven seasonal storage option

• At least 40 systems in operation• Over 60 more in development• The majority store potable water

Conceptual Reclaimed Water ASR Well

Class V, Group 3Class V, Group 3Injection WellInjection Well

Typical Recovery OperationTypical Recovery Operation(Excess Demand)(Excess Demand)

WRF orWRF orAWTPAWTP

Public AccessReuse System

Typical Recharge OperationTypical Recharge Operation(Excess Supply)(Excess Supply)

Public AccessReuse System

WRF orWRF orAWTPAWTP

Class V, Group 3Class V, Group 3Injection WellInjection Well

Zone of poor quality water

Low Permeability

Zone

Moderate Permeability

Zone

Low Permeability

Zone

3,000 mg/L TDS

Reclaimed water ASR programs are developing quickly along Florida’s west coast

Bradenton

Peace River

Bonita Springs

Marco Island RO WTP

Potable Water ASR ProjectPartially Treated Surface Water ASR Project

Tampa

Reclaimed Water ASR Project

South HillsboroughSt. Petersburg

SouthwestManatee County

Sarasota County

Lehigh Acres

Marco Island WWTP

Manatee County

Central Hillsborough

Manatee County North

City of Sarasota

Fort Myers

Englewood

Northwest Hillsborough

Pinellas CountyLargo

Clearwater

Florida is out in front nationally in development of reclaimed water ASR

• Other states are less comfortable with reclaimed water use

• Artificial recharge and indirect potable reuse are more active elsewhere

• Other areas appear to be lagging in matching the quality of water to intended use

IDID--11

Reclaimed water ASR will become more widespread in the near future• Similar projects are underway in

– Arizona– California

• Other states recognize the need but must develop regulatory framework– South Carolina -- North Carolina– Georgia --Texas

• Yet other states must still become more comfortable with reuse

ASR will be the key to successful optimization of many reuse programs

• Reuse is limited to 50 to 60 percent of annual ADF without seasonal storage for many Florida reuse systems

• Proper ASR development in many cases–is the lowest cost option to expand system–has the lowest land requirements–is environmentally sensitive–has no negative aesthetics

Reclaimed water ASR programs take several years to implement

• Feasibility Study (3 to 6 months)• Permitting (10 to 15 months)• Well Construction (6 to 12 months)• Operational testing (2 to 4 years)

July 2001August 1996 January 1997

A feasibility study is important to address ASR permitting, siting & development issues• Well siting • Reclaimed water

characterization• Existing wastewater

infrastructure and reuse system

• Supply and demand issues• Existing groundwater users• Native water quality and

hydrogeology• Drilling and testing program

Native water quality and hydrogeology drive selection of optimum storage zone and permitting strategy

Permitting Not Feasible

Limited Recovery

Proper Storage Zone SelectionMaximizes Recovery And Aids in

Permit Approval

The reclaimed water must meet all primary Drinking Water Standards• Phthalate concerns may have to be addressed• Disinfection by-products can be successfully

addressed through chloramination– TTHMs reduced from 175 ppb to 30 ppb at NW

Hillsborough Co.• Nitrogen series may also

require process changes– Nitrate of <10 mg/L– Nitrite of <1 mg/L– Ammonia is not regulated

Coliform standards must be met at the well• Total coliform of 4 cfu/100 mL; not a reuse - but

a groundwater discharge - standard– Reuse systems are not sterile conveyance systems, not

constructed/operated as a drinking water system – Chloramines are more persistent than free chlorine,

but generally not as strong a disinfectant; maintaining elevated TRC at wellhead should control TC

• Fecal coliform must be (and have been) absent• Alternative disinfection

such as UV may be needed at the wellhead– Capital $80-$100k/well– O&M $3-$5k/year/well

UV

Secondary Drinking Water Standards must also be met

• Secondary DWSs are aesthetic rather than health-based standards– Color -- Manganese -- TDS --pH– Odor -- Iron --Chloride

• Ambient groundwater is alternative standard• Exemptions are available and relatively easy to

obtain– WQCEs, ZODs, Chapter 120 Variance

• Regulated as average concentrations, rather than single sample exceedence

0

50

100

150

200

250

300

350

400

450

500

HillsboroughCounty ASR Well

Limestone

Limestone/Clay

ClaySand

Semi-ConfiningZone

Limestone/Clay

Semi-ConfiningZone

ExistingStorage ZoneLimestone

Proximity of the saltwater interface has limited recovery from some ASR wells

• Upconing may occur during recovery

• Saltwater interface is typically close to the base of the well

• Important not to over-stress the well early– Lower recovery

rates– Vol in > Vol out

Initial test results from EWD are encouraging

• Storage zone is saline -20,000 mg/L TDS

• 90 MG was recharged during first cycle

• Only 12 MG was recovered– Due to lack of reuse demand not

water quality • Recovered water quality

approached 1,100 mg/L TDS• Acceptable endpoint estimated at 2,000 mg/L

– Recovery estimated at over 30 percent if reuse customers were available

– Recovery should improve w/ increased storage

Blending of ASR water with reclaimed water will help meet irrigation quality

Water ReclamationFacility

1 mgd @ 2000 mg/L TDS

Chlorine Contact Basin

3 mgd @1000 mg/L TDS

(400 mg/L chlorides)

ASR Well

2000 mg/L TDS

2 mgd @500 mg/L TDS

Cycle testing is an important phase of the ASR program• Operational testing

necessary to justify FDEP operating permit issuance

• Defines recovery potential of the stored water

• Allows demonstration that drinking water standards can be maintained during recharge events

Sufficient reject pond capacity provides flexibility during cycle testing

TPW-1Existing

Blowdown Pond

• High turbidity observed for 1 to 2 hours following recovery startup

• Existing pond sited for 15 to 20 minutes of recovery

• Larger pond will allow longer blowdown period during multiple ASR well startups

Reclaimed water ASR projects should be easier to develop than potable ASR• Source water costs “pennies” per 1000

gallons (pumping costs), therefore investment is minimal to develop “bubbles”

• Recovery to approximately twice the salinity of drinking water for many irrigation applications

• No re-treatment should be required prior to placing into the reuse system, following water quality demonstration

Major hurdles have been cleared over the past several years in Florida

PermittingFeasibility

Native water quality

characteri-zation

Authorization to Use

OperatingPermit

Recharge Water

Quality Issues

One hurdle remains . . .

Summary• Sustainable dry season supplies are becoming

increasingly critical for reuse reliability• ASR allows the reuse utility to maximize use

and minimize disposal of this resource• Substantial progress

has been made in Florida to recognize the benefits of reclaimed water ASR

• Further progress is needed to streamline implementation of these programs

Summary (cont.)• Reclaimed water ASR is a new use of a proven

technology to maximize reuse• Favorably received by FL regulatory agencies• May allow utility to transition into a zero-

discharge facility• Economical approach to large volumes of

seasonal storage• Future saltwater intrusion barriers or indirect

potable reuse applications may develop, but additional treatment is likely required

Status of ASR in Florida....& Beyond...

Presented at the Presented at the

Presented byPresented by

Mark B. McNeal, P.G.Mark B. McNeal, P.G.

January 24th, 2003January 24th, 2003

Emerging Issues Facing Emerging Issues Facing Water ReuseWater ReuseSponsored bySponsored by

Florida Water Environment AssociationFlorida Water Environment Association

In association withIn association withFlorida Department of Environmental ProtectionFlorida Department of Environmental ProtectionWateReuse AssociationWateReuse Association

Coronado Springs ResortCoronado Springs ResortLake Buena Vista, FloridaLake Buena Vista, Florida