Land-Applied Wastewater Effluent Impactson the Edwards Aquifer

by: D. Lauren Ross, Ph. D., P. E. Glenrose Engineering, Inc. 512.326.8880glenrose.com

Acknowledgements:City of

AustinU.S.

Geological Survey

BS/EACDLCRA

Fragile Streams

Naturally low flow

Naturally low nutrients

Fragile Aquifer

Rapid FlowNo FiltrationRecharged

through both Upland and Stream Features

Texas Land Application Permits in the San Antonio

and Barton Springs Edwards Aquifer Recharge Zones

NONE

Texas Land Application Permits in the San Antonio

and Barton Springs Edwards Aquifer Contributing

Zones

67

Texas Land Application Permits

San Antonio and Barton Springs Edwards Aquifer

Contributing Zones

Barton Springs Edwards Aquifer Contributing Zone: 26

San Antonio Edwards Aquifer Contributing Zone: 41

Barton Springs

San Antonio Edwards

0

1

2

3

4

5

6

7

0

500

1,000

1,500

2,000

2,500

5.75

3.18

2,063

1,461

Total Flow (MGD)Total Irrigated Area (acres)

Tota

l Flo

w (M

GD

)

Irri

gate

d Ar

ea (a

cres

)

24 Times the TLAPed Effluent in the Barton Springs Compared to

the San Antonio Edwards Aquifer

Contributing Zones on an Area Basis

What Determines A Protective TLAP?

Effluent Treatment Technology

Effluent Treatment StandardsEffluent Storage

RequirementsIrrigation Area Requirements

Different Effluent Treatment Technologies

Activated Sludge: 44 (70%)Membrane Bioreactor: 2 (3%)Others:

Facultative LagoonSeptic TankNot Specified (2)

Widely Different Effluent Standards

Daily Average BOD and TSS Range from 5 to 30 mg/l

16 have no effluent limitsOnly 10 with nutrient limitsOnly 2 with total nitrogen

limits

Widely Different Effluent Storage Requirements

21 Systems with no storage requirement

Required Days Storage Ranges from 0.08 to 308 Days

Average for Subsurface Irrigation: 5.8 Days

Average for Surface Irrigation: 70 Days

Widely Different Effluent Irrigation Area Requirements

Application Rates Range from 0.08 to 12.20 acre-feet per acre per year

The most common rate is 4.88 acre-feet per acre per year (0.1 gal/day/sf)

Evidence of Stream Degradation

No Monitoring RequirementsNutrients are Most MobileCompounding and Confusing

Nutrient SourcesNutrients can “disappear” out of

the water column into algae growth

0.68

0.47

0.19

0.63

0.21

0.08

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

Effluent-Irrigated Golf Course

Effluent Irrigated Residential

Residential on Septic

Nitr

ate

as N

itrog

en (m

g/l)

Mean

Median

Nitrate Concentration in Barton Creek Canyons Baseflow (COA, 1997)

Degradation Evidence: Belterra Subdivision

0.47

0.82

1.31

0.49 0.450.53

0

0.2

0.4

0.6

0.8

1

1.2

1.4

Belterra Spring at

Aspen Drive

Bear Creek at Davis Property

Line

Bear Creek Riffle above Davis Pond

Bear Creek in Davis Pond

Bear Creek Pond at Bear

Creek Pass

Bear Creek Riffle at Bear

Creek Pass

Nitr

ate

(mg/

l as N

)TLAP Irrigation

Area

Degradation Evidence: Barton Creek West

Increasing Nitrate Concentrations in Scenic Bluff Springs Over Time

Degradation Evidence: West Cypress Hills

West Lick Creek Downstream from Pedernales Canyon Trail

Algae in East Lick Creek Downstream from Pedernales

Canyon Trail

Degradation Evidence: West Cypress Hills

Broken Effluent Irrigation Pipe

Degradation Evidence: West Cypress Hills

Broken Effluent Irrigation Pipe

Degradation Evidence: West Cypress Hills

Lick Creek Below Broken Effluent Irrigation Pipe

Degradation Evidence: West Cypress Hills

Algae Down Stream from Effluent Irrigation

Degradation Evidence: West Cypress Hills

0.03 0.03 0.03

0.240.09

0.56

0.91

0.070.09 0.030.13

0.62 0.59

0.190.03

0.21 0.190.05 0.03

0.38

0.74 0.67

2.87

0.24

0.70

0.30

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

Lick Creek above Horse

Barn Trib: Drains Hwy 71

Horse Barn Tributary at Lick Creek

Grassy Swale Tributary to E.

Lick Creek

Seep on E. Lick Creek Right

Bank

E. Lick Creek above Cypress

Ranch Blvd

E. Lick Creek above

Detention Pond

West Tributary to Detention

Pond

Detention Pond

E. Lick Creek Downstream

from Detention

Pond

E. Lick Creek at Pedernales Canyon Trail

Nitr

ate

-N (m

g/L)

June 2007

September 2007

October 2009

TLAP Irrigation Area

TLAP NoncomplianceFailure to Monitor Soil: Only 2 of 64 TLAPs with

reported dataApplication Misinformation (Jeremiah Venture):Effluent Irrigation Proposed for Rocky SoilsFailure to Identify Karst FeaturesWater Balance Based on Western

Evapotranspiration Values

Effluent Irrigation Proposed for Rocky Soils

Failure to Identify Recharge Features

Images from Hauwert, Preliminary Phase I Assessment of the Jeremiah Ventures Site, September 25, 2009.

Failure to

Identify Recharg

e Feature

s

Misuse of Water Balance Method

Appli

cant's

Wate

r Bala

nce

TCEQ

Require

ments

TCEQ

Require

ments

with 20

07 Ra

infall

0

50

100

150

200

250

107.19

137.9187.13

60.7111.4

198.5

Required Irrigation Area (acres)Required Storage (acre-feet)

TLAP RecommendationsEliminate TLAPs on the Edwards Aquifer

Recharge Zone

TLAP RecommendationsEliminate TLAPs on the Edwards Aquifer

Recharge ZoneEstablish Consistent Effluent LimitsTotal Nitrogen: 3 milligrams per literTotal Phosphorous: 0.1 milligram per liter

TLAP RecommendationsStandardize Effluent Irrigation Requirements

TLAP RecommendationsStandardize Effluent Irrigation RequirementsStandardize Effluent Storage Requirements

TLAP RecommendationsStandardize Effluent Irrigation RequirementsStandardize Effluent Storage RequirementsEliminate Leaching Allowance

TLAP RecommendationsStandardize Effluent Irrigation RequirementsStandardize Effluent Storage RequirementsEliminate Leaching AllowanceRequire Soil, Spring, Stream, and Well

Monitoring with Re-permitting Triggers

TLAP RecommendationsStandardize Effluent Irrigation RequirementsStandardize Effluent Storage RequirementsEliminate Leaching AllowanceRequire Soil, Spring, Stream, and Well

Monitoring with Re-permitting TriggersRequire Soil Monitoring and Automatic

Response to Saturated or Frozen Soil Conditions