— NOAA / USGS Cooperative Program —

Simulation of Coastal Wastewater Injection in Hawaii using SUTRA

… and the Value of Compelling Visualizations in Conveying Results

to the Non-Specialist Public

Chip Hunt

U.S. Geological Survey, Honolulu, HI

cdhunt@usgs.gov

Lahaina

Kahului

Maui Municipal Wastewater Injection Sites

1500 m

3000 m

Photo: Jennifer Smith

Nuisance algal blooms …… are land-derived nutrients a contributing factor ?

Hypnea musciformisFunding by NOAA ECOHAB (Ecology and Oceanography of Harmful Algae Blooms)

ObjectivesEstimate ground-water nutrient loads

Identify useful wastewater tracers

Answer injection-plume questions:- Where does it go?- “We inject this stuff, and if it gets to the

coast …”

- Plume width at coast?

Dryland forest, low-intensity ranching

Resort / urban coastal strip

Sugar cane(fertilizers)

1500 m

3000 m

Some

smal

l

farm

s on

upp

er

road

Photo: Univ. of Photo: Univ. of Hawaii Coastal Hawaii Coastal Geology GroupGeology Group

Sugar caneSugar cane

CondominiumsCondominiums

Photo: Univ. of Hawaii Coastal Geology Group

Dryland scrub-forest Dryland scrub-forest in uplandsin uplands

Resorts / Resorts / condoscondos

Suburban residentialSuburban residential

Photo: NOAA Coastal

Habitat Atlas

Shallow fringing reef

+/-1m

No fringing reef

No fringing reef

Basalt promontory

Basalt promontory

Kalama Kalama ParkPark

Approximate plume extent

Photo: NOAA Coastal Habitat Atlas

Sand beach; Sand beach; no fringing reef no fringing reef

Basalt promontory Basalt promontory

Basalt promontory Basalt promontory

11,400 m3/d injected effluent

Ambient GW flow 6,600 m3/d per km coast

Plume 1.5 km wide

N=7.3 mg/L= 6x Background conc

P=1.7 mg/L= 26x Background conc

13 km

coast

3-D Ground-Water ModelCode: SUTRA (Voss & Provost, 2002, USGS)

Variable-density flow & solute transport

Solute = Salt (freshwater-saltwater flow)

DID NOT simulate nutrient transport

Post-processing to visualize plume, GW age

Kh= 3000 m/d Kh:Kv anisotropy=200:1

aL = 76 m aT = .022 m

Model Mesh

74,592 elements 63

x 37 vertical

32

Saltwater

Saltwater

circulation

Recharge nodes vFreshwater Lens (Natural flow)

Freshwater

Mixing zone

Mixing zoneBrackish waterBrackish water

Visualizations via

Model Viewer (Hsieh and Winston, 2002, USGS)

< Constant pressure nodes

Salinity Visualization3% l

edge

3% l

edge

Injection Plume is BuoyantInjection Plume is Buoyant

20%20%

40%40%

60%60%

80%80%

3%3%

Percent Percent seawaterseawater

100%100%

Effluent = 1% salinity (buoyant)Effluent = 1% salinity (buoyant) ShorelineShoreline

- looking northwest- looking northwest

Injection interval Injection interval -14 to -58 m within mixing -14 to -58 m within mixing

zone and saltwater)zone and saltwater)

3% l

edge

Upstream shoulder

(fluid fresher than 3% removed)

Velocity vectors show Velocity vectors show regional flow diverging regional flow diverging around plumearound plume

Salinity Visualization

Salinity100%

0%3%

ledge

Upstream shoulder

Effluent-Tracer Visualization

100%

20%

Percent effluent

fluid more than 90% effluent

removed

Plume internal structure, 20% shells

100%

0%

Percent effluent

20%20%40%40%

60%60%80%80%

100%

5%

Percent effluent

Plume width1.5 km at shore

60% effluent at shore (yellow)

Cove Park Cove Park

Kalama Kalama Park Park

Welekahao RdWelekahao Rd

Halama St Halama St

algae sitealgae site

Lipoa St Lipoa St

algae sitealgae site

Lipoa StLipoa St

Superimpose over tax map

and landmarks

Ground-Water Ageat Water Table Years

fluid younger than 1 year removed

100%

0%

Percent effluent

Downgradient well in plume was anoxic, with wastewater tracers, denitrification, and heavy d15N

Algal tissue 15N

highest near plume

HypneaHypnea

UlvaUlva

C. Smith, J. Smith, C. Smith, J. Smith, Univ. of HawaiiUniv. of Hawaii

Nutrient load per kilometer coast(kg / day – km coast)

Upland background N=7.8P=.44

Injected N= 55 ( 7xB)P= 13 (30xB)

1.5km13 km

Attenuated* wastewater nutrient load(kg / day – km coast)

Attenuated N= 27=3.5xB was 7x….

P=1.5=3.4xB was 30x….

1.5km13 km

* very speculative, based on just

1 well in plume

Houses on cess- pools

Injection

Urban Nutrient Load? Don’t know.

??

Background

Fertilizers

… rough work but somebody’s gotta do it

Enough modeling, let’s go lookEnough modeling, let’s go lookWading survey for wastewater tracers

Photo: Joshua Marvit, Hawaii Dept. of Health

Funding: Hawaii Dept. of Health, USEPA

Water-quality meter and GPS

Smaller platform: coolers

strapped together

Multiparameter water-quality

meter

GPS unit

Even better:

Approximate plume extent

Wading Salinity (red=freshest)

Injection wells

Approximate plume extent

Fabric-Brightener Fluorescence (water-column samples)

Injection wells

Also:

- Caffeine- Carbamazepine- NO3= 2-4 mg/L- Algal 15N= 18 * (* Meghan Dailer)

Funding by NOAA ECOHAB (Ecology and Oceanography of Harmful Algae Blooms)

Online report: