Track D - University of Minnesota

Rapid Infiltration Measurement for
Assessing Infiltration of BMPs
Farzana Ahmed
St. Anthony Falls Laboratory
October 19 th , 2010

Overview
• Basic concept.
• Description and Procedure.
• Application and Advantage
• Case Studies
• Conclusion
http://stormwater.safl.umn.edu/

Basic concept
http://stormwater.safl.umn.edu/

Why is it important to measure the
infiltration rate
• To determine performance and schedule
maintenance
‣An important indicator to determine the
functionality of the stormwater BMPs.
‣Accumulation of soil particles will reduce the
infiltration rate of soil.
‣Compaction during construction will reduce the
infiltration rate of soil by reducing the pore
volume.
http://stormwater.safl.umn.edu/

Spatial variation of K sat
• Images courtesy of N. Olson
http://stormwater.safl.umn.edu/

Spatial variation of K sat
Image courtesy B. Asleson & R. Nestingen
http://stormwater.safl.umn.edu/

Spatial variation of K sat
• Need ~20 infiltration measurements.
• Need a device to measure the infiltration rate
which is fast, simple and requires a lower volume
of water.
http://stormwater.safl.umn.edu/

Description and Procedure
http://stormwater.safl.umn.edu/

Modified Philip Dunne Infiltrometer
(MPD Infiltrometer)
• 42 cm long - 10 cm inner
diameter cylinder - two
parts.
• Clear acrylic pipe and
finished steel.
• A metric measuring tape -
adhered outside of the pipe
• Stopwatch
http://stormwater.safl.umn.edu/

Modified Philip Dunne Infiltrometer
(MPD Infiltrometer)
Procedure of MPD
Infiltrometer test
Field Procedure Lab Procedure Computer procedure
http://stormwater.safl.umn.edu/

Modified Philip Dunne Infiltrometer
(MPD Infiltrometer)
Field Procedure
• Take soil samples
http://stormwater.safl.umn.edu/

Modified Philip Dunne Infiltrometer
(MPD Infiltrometer)
• Pound the MPD into
the soil
http://stormwater.safl.umn.edu/

Modified Philip Dunne Infiltrometer
• Fill the MPD with
water.
• Record the height
of water level with
time.
(MPD Infiltrometer)
http://stormwater.safl.umn.edu/

Modified Philip Dunne Infiltrometer
(MPD Infiltrometer)
Lab Procedure
• Measure initial moisture content and bulk density
according to ASTM methods.
http://stormwater.safl.umn.edu/

Modified Philip Dunne Infiltrometer
Computer procedure
(MPD Infiltrometer)
• Input the initial moisture content, the saturated
moisture content for that type of soil, the water
level vs time data and the bulk density of soil into
the MPD spreadsheet.
http://stormwater.safl.umn.edu/

Modified Philip Dunne Infiltrometer
(MPD Infiltrometer)
t http://stormwater.safl.umn.edu/

Modified Philip Dunne Infiltrometer
Results
(MPD Infiltrometer)
t • Saturated t hydraulic conductivity it (K sat ) and
• Soil suction (C) of the upper ~30 cm of soil.
• K sat : Indicates the ease with which water can
move through the pore space when the soil is in
saturated condition.
• The attraction force that the soil exerts on the
water is termed soil suction (C).
http://stormwater.safl.umn.edu/

Application and Advantage
http://stormwater.safl.umn.edu/

Modified Philip Dunne Infiltrometer
Application
(MPD Infiltrometer)
• K sat and C values- to calculate the drain time and amount of surface runoff.
• To identify the hydrologic soil group.
• Has been used in rain gardens, an infiltration basin, one swale and a study
of tillage and compost to remediate compact soil.
http://stormwater.safl.umn.edu/

Modified Philip Dunne Infiltrometer
(MPD Infiltrometer)
t Advantage of using the MPD Infiltrometer
• Relatively l quick
• Simple and inexpensive device
• Requires less volume of water.
• MPD measures the K sat value of the top 30 cm of media.
http://stormwater.safl.umn.edu/

Case Studies
http://stormwater.safl.umn.edu/

Application of the K sat and C values
• Case Study I
‣ Type of BMP: Infiltration basin
‣ Area: 2.5% of the impervious watershed
‣ Rainfall event: 3month 24hr storm (2.5 cm/day)
‣ Depression storage: 183cm
‣ Moderate soil moisture
Type of soil Ksat (cm/hr) C (cm) Drain time Surface runoff (cm)
Loamy sand 3 6 13 hr 0
Sandy loam 1 11 2 days, 8 hr 0
Silt loam 0.65 17 4 days, 9 hr 0
Sandy clay loam 0.15 22 27 days 0
Clay 0.03 32 140 days 0
http://stormwater.safl.umn.edu/

Application of the K sat and C values
• Case Study II
‣ Type of BMP: Bioretention Practice
‣ Area: 5% of the impervious watershed
‣ Rainfall event: 3month 24hr storm (2.5 cm/day)
‣ Depression storage: 46cm
‣ Moderate soil moisture
Type of soil Ksat (cm/hr) C (cm) Drain time Surface runoff (cm)
Loamy sand 3 6 No ponding 0
Sandy loam 1 11 22 hr 0
Silt loam 0.65 17 2 days 0
Sandy clay loam 0.15 22 12 days 10 hr 0
Clay 0.03 32 63 days 12 hr 4.2
http://stormwater.safl.umn.edu/

Application of the K sat and C values
• Case Study III
‣ Type of BMP: Roadside Swale (drainage ditch)
‣ Area: 15% of the impervious watershed
‣ Rainfall event: 3month 24hr storm (2.54 cm/day)
‣ Depression storage: 92cm
‣ Moderate soil moisture
Type of soil Ksat (cm/hr) C (cm) Drain time (hr) Surface runoff (cm)
Loamy sand 3 6 No ponding 0
Sandy loam 1 11 3 hr 0
Silt loam 0.65 17 12 hr 0
Sandy clay loam 0.15 22 3 days 2 hr 0
Clay 0.03 32 22 days 4 hr 0
http://stormwater.safl.umn.edu/

Conclusions
• Measurement of Ksat is important to determine
performance and schedule maintenance.
• We need to know the spatial distribution of K sat
to estimate infiltration rate.
• MPD infiltrometer is designed for spatial
distribution
– has been used at up to 20 locations simultaneously,
allowing for up to 40 measurements per day, with a
three-person team.
http://stormwater.safl.umn.edu/

Thank you
Questions
&
Comments
http://stormwater.safl.umn.edu/

Improved Site Investigation
Procedures for Long‐term Success of
Stormwater BMPs – Lessons Learned
from Soil ilSi Science
Dave Bauer, PSS, CPESC
Rice Creek Watershed District
Dan Wheeler
University of Minnesota

Raingardens & Septic Systems
• Both rely on soil for the acceptance and
treatment of water
• 36% of infiltration/filtration BMPs installed to
meet Rice Creek Rules between 2003 and
2007 failed.
• 2% of SSTS (Septic Systems) constructed
between 1984 and 2004 failed fildin Ottertail
County.

Raingarden
Septic System

Comparing Failures
• When a rain garden fails, you generally have
an unplanned pond, sometimes with an odor,
that generally doesn’t fit in the landscape.
• When a septic system fails, you have a oozing
spring of human waste, which can stink to
high heaven and make people sick.

Raingarden Failure

Septic System Failures

A Standard Wastewater Site Evaluation Exists…
• 1980 EPA Design Manual
• Earlier in MN ISTS SSRules
• ASTM Standards D5879, D5921
*Key: Standard forms

A Standard Site Evaluation =
An Appropriate Design
1 st a complete lt preliminary
i
evaluation should be
completed
Soils of the area are
important to characterize
and understand
Hydrology, soil and
landscape variability, and
slope
Physical constraints of site
H. Soil Survey Information (from web soil survey ) Map
Map Units on Parcel 730B, 1110, 1253C
List landforms hills, swales, outwash plains
Slope Range 2-6, 0-2, 6-15
Parent materials Till Outwash Loess Bedrock Alluvium
Landscape Position Summit Shoulder Backslope Footslope Toeslope
(circle all that apply ) Colluvium Lacustrine Organic Cut/Fill (circle all that apply ) Depression Stream Terrace Man-made Plain
Map Unit
Ratings
N/A Minimum bedrock depth
Maximum Bedrock Depth Minimum Redox Depth
~0"
Maximum Redox Depth
>63"
Septic Tank Absoprtion Field - Trench (MN) moderately limited, extremely limited, moderately limited
Septic Tank Absorption Field - At-grade (MN) not limited, extremely limited, slightly limited
Septic Tank Absorption Field - Mound (MN) slightly limited, very limited, extremely limited
4. Preliminary Soil Profile Information (from web soil survey - map unit description & official series descriptions )
Map Unit 730B
Depth Texture(s) Structure(s) Consistence
Other (flooding, ponding, etc.)
Horizon 1
0-2" ls weak granular fr
Horizon 2 2-6" ls weak blocky
fr
E horizon
Horizon 3
6-15" ls weak blocky
fr
E horizon
Horizon 4 15-21" sl mod blocky
fr
clay films
Horizon 5 21-33" s single grain
loose
Map Unit
1110
Depth Texture(s) Structure(s) Consistence
Other (flooding, ponding, etc.)
Horizon 1 0-10" sl weak blocky
fr
N 2.5/0
Horizon 2 10-14" sl weak blocky fr
N 2.5/0
Horizon 3 14-20" ls weak blocky
vfr
redox conc.
Horizon 4 20-34" ls weak blocky vfr
redox dep/conc.
Horizon 5 34-40" cos single grain
loose
redox dep/conc.
Map Unit 1253C
Depth Texture(s) Structure(s) Consistence
Other (flooding, ponding, etc.)
Horizon 1 04" 0-4 grls weak granular
vfr
Horizon 2 4-11" vgrcos single grain loose
~35% gravel
Horizon 3 11-24" egrcos single grain
loose
~70% gravel
Horizon 4 24-43" grs single grain loose
~16% gravel
Horizon 5 43-63" grs/grcos single grain
loose
~15% gravel

What SHOULD be on the Site
Evaluation
• Surface Water Runoff Location(s)
• Setbacks
– Bedrock
• Slope
– Contours
– Shape
• System location
– Scale
• Site evaluation
– Soil observations (description and number)
– Percolation tests or water movement tests

MPCA Stormwater Manual, 2005
Requires bulk density (or soil structure)
Depth to seasonal saturation
(redoximorphic features identification)

Blue Thumb’s Site Investigation
From Blue Thumb Guide to Raingardens
(summarized)
• Find location that makes sense for drainage
• Look for things to avoid (utilities, within 10’ of
home, soggy part of yard, bedrock)
• Run infiltration test at site
• Extrapolate tested rate to 24 hours to get
maximum depth, with a max depth of 12
inches.

Blue Thumb
Infiltration ti testt
• Dig 8” diameter hole, 8” deep
• Fill with water
• Wait one or two hours to saturate
soil
• Refill hole
• Measure rate of drop at regular
time intervals
– Sand: 15 minute intervals, for 1 hour
– Clay: hourly intervals, for 4 hours

Site Investigation Success
• Using Blue Thumb site evaluation methods,
only 1 out of 23 raingardens installed
voluntarily as part of Rice Creek cost share
program have failed, 4%.

Lessons Learned
• Standardized site evaluations for infiltration‐
based stormwater strategies will increase
success rate
• For regulatory sites, where large
features/volumes are anticipated, adopting
wastewater‐based site evaluations seem
appropriate
• Forms provide a checklist for design/review

Looking Forward…
• Designers, Inspectors and Installers need
additional training in soil and site evaluation
– Rice Creek Watershed District is sponsoring a 1‐
day soil and site evaluation workshop in May
2011,
– A certification program is another method for
providing this additional training, or
– LGUs oversee proper soil and site evaluations

When Do We Need to
Replace Bioretention ti Media
Joel Morgan
St. Anthony Falls Laboratory
University of Minnesota

Outline
• Introduction
• Background
• Experiment Setup
• Results and Discussion
• Application
• Conclusions

Introduction
Figure 1 Typical Rain Garden. Adapted from Davis et al (2009)
-Introduction and Background
-Experiment Setup
-Results and Discussion
-Application
-Conclusion

Objective
-Introduction and Background
-Experiment Setup
-Results and Discussion
-Application
-Conclusion

Objective
• Develop understanding of ability of rain
garden media to remove heavy metals
-Introduction and Background
-Experiment Setup
-Results and Discussion
-Application
-Conclusion

Objective
• Develop understanding of ability of rain
garden media to remove heavy metals
• Develop a life cycle analysis of a rain
garden
-Introduction and Background
-Experiment Setup
-Results and Discussion
-Application
-Conclusion

Objective
• Develop understanding of ability of rain
garden media to remove heavy metals
• Develop a life cycle analysis of a rain
garden
• Provide suggestions for preventative
and non-routine maintenance to extend
life span
-Introduction and Background
-Experiment Setup
-Results and Discussion
-Application
-Conclusion

Background
Source Transport Consequence
-Introduction and Background
-Experiment Setup
-Results and Discussion
-Application
-Conclusion

Background
• Sorption is the primary removal process
-Introduction and Background
-Experiment Setup
-Results and Discussion
-Application
-Conclusion

Background
• Sorption is the primary removal process
-Introduction and Background
-Experiment Setup
-Results and Discussion
-Application
-Conclusion

Background
• Sorption is the primary removal process
Zn 2+ Cd 2+
Zn 2+
Cu 2+
Zn 2+ Cd 2+
Cu 2+ Cu 2+ -Introduction and Background
-Experiment Setup
-Results and Discussion
-Application
-Conclusion

Experimental Setup
• We are testing ti Compost, Sand, and Soil
-Introduction and Background
-Experiment Setup
-Results and Discussion
-Application
-Conclusion

Experimental Setup
• We are testing ti Compost, Sand, and Soil
• Analyzed samples on an ICP at the
Soils Lab at the U of M’s St. Paul
campus
-Introduction and Background
-Experiment Setup
-Results and Discussion
-Application
-Conclusion

Experimental Setup
• We are testing ti Compost, Sand, and Soil
• Type of Setup
-Introduction and Background
-Experiment Setup
-Results and Discussion
-Application
-Conclusion

Experimental Setup
-Introduction and Background
-Experiment Setup
-Results and Discussion
-Application
-Conclusion

Experimental Setup
-Introduction and Background
-Experiment Setup
-Results and Discussion
-Application
-Conclusion

Experimental Setup
-Introduction and Background
-Experiment Setup
-Results and Discussion
-Application
-Conclusion

Experimental Setup
-Introduction and Background
-Experiment Setup
-Results and Discussion
-Application
-Conclusion

Experimental Setup
1.2
1
C/Co
0.8
0.6
0.4
0.2
0
0 5 10 15 20 25 30 35
Time
-Introduction and Background
-Experiment Setup
-Results and Discussion
-Application
-Conclusion

Experimental Setup
-Introduction and Background
-Experiment Setup
-Results and Discussion
-Application
-Conclusion

Experimental Setup
-Introduction and Background
-Experiment Setup
-Results and Discussion
-Application
-Conclusion

Experimental Results
• Background concentration ti of metals on
compost (mg/kg)
Cadmium Copper Zinc
Sample 1 0273 0.273 13.962 63.422
Duplicate 0.341 13.877 57.931
-Introduction and Background
-Experiment Setup
-Results and Discussion
-Application
-Conclusion

Experimental Results
• Sorption Kinetics
Cadmium sorption to 1.0 g of compost.
Percent Re emoved
100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%
45
40
35
30
25
20
15
10
5
0
0 10 20 30 40 50 60
Time (hrs)
q (ug /g)
-Introduction and Background
-Experiment Setup
-Results and Discussion
-Application
-Conclusion

Experimental Results
• Sorption Equilibrium
i
-Introduction and Background
-Experiment Setup
-Results and Discussion
-Application
-Conclusion

Experimental Results
• Sorption Equilibrium
i
– Purpose is to determine maximum sorption
capacity, q
-Introduction and Background
-Experiment Setup
-Results and Discussion
-Application
-Conclusion

Experimental Results
• Sorption Equilibrium
i
Cadmium sorption to compost.
Mass removed
per mass of
compost
3.000
2.500
2.000
1.500
1.000
K = 20.28 L/g
1/n = 0.93
0.500
0.000
0.000 0.020 0.040 0.060 0.080 0.100
Cadmium Concentration (mg/L)
-Introduction and Background
-Experiment Setup
-Results and Discussion
-Application
-Conclusion

Experimental Results
• Phosphorus h Leaching
1400
1200
1000
Conc.
(ug/L)
800
600
400
y = 284.54x 0.326
R² = 0.9585
200
0
0 10 20 30 40 50
Time (hrs)
-Introduction and Background
-Experiment Setup
-Results and Discussion
-Application
-Conclusion

Phosphorus Removal - Iron
ion Reta ained
P hosphor rus Fract
1.2
• Phosphorus Leaching
1
0.8
0.6
0.4
0.2
0
100% sand
5% iron filings
2% iron filings
0.3% iron filings
0 5 10 15 20 25 30 35 40
Years of Service
HLR = 5.6 m/yr
Erickson et al, 2010
-Introduction and Background
-Experiment Setup
-Results and Discussion
-Application
-Conclusion

Application
-Introduction and Background
-Experiment Setup
-Results and Discussion
-Application
-Conclusion

Application
• Assume rain gardens infiltrate t first ½” of
runoff
• Rain Garden area to drainage area ratio
of 0.05 and a runoff coefficient of 0.5
• Annual depth of runoff treated of 6.44
m/yr for the Minneapolis/St. Paul area
-Introduction and Background
-Experiment Setup
-Results and Discussion
-Application
-Conclusion

Application
• Assume a rain garden made of 70/30
sand and compost by volume
• Bulk Density
– Sand: 1600 kg/m 3
– Compost: 500 kg/m 3 -Introduction and Background
-Experiment Setup
-Results and Discussion
-Application
-Conclusion

Application
where m is the mass dosage rate of rain
garden media, Q is the flow rate, and q
is the sorption capacity
q
-Introduction and Background
-Experiment Setup
-Results and Discussion
-Application
-Conclusion

Application
• Depth of Water Treated at 30” depth
– Cadmium: 2,500 m
– Zinc: 4,400 m
• Time to breakthrough
– Cadmium: 390 years
– Zinc: 680 years
-Introduction and Background
-Experiment Setup
-Results and Discussion
-Application
-Conclusion

Application
• Depth of Water Treated at 6” depth
– Cadmium: 507 m
– Zinc: 935 m
• Time to breakthrough
– Cadmium: 79 years
– Zinc: 145 years
-Introduction and Background
-Experiment Setup
-Results and Discussion
-Application
-Conclusion

Conclusion
• A little bit of compost goes a long way
-Introduction and Background
-Experiment Setup
-Results and Discussion
-Application
-Conclusion

Conclusion
• A little bit of compost goes a long way
• Compost leaches phosphorus
-Introduction and Background
-Experiment Setup
-Results and Discussion
-Application
-Conclusion

Conclusion
• A little bit of compost goes a long way
• Compost leaches phosphorus
• Rain gardens should be designed with
2-stage removal in mind
-Introduction and Background
-Experiment Setup
-Results and Discussion
-Application
-Conclusion

Conclusion
Compost Amended Sand
Iron Enhanced Sand Filter
-Introduction and Background
-Experiment Setup
-Results and Discussion
-Application
-Conclusion

Zn 2+ Conclusion
Cd
2+
Conclusion
Cd
Zn 2+
2+
Cu 2+
P
Compost Amended Sand
P
Cu 2+
P
P
P
P
Iron Enhanced Sand Filter
-Introduction and Background
-Experiment Setup
-Results and Discussion
-Application
-Conclusion

Acknowledgements
• Minnesota Mulch and Soil
• Minnesota Pollution Control Agency
• Professors John Gulliver and Ray
Hozalski
• Andy Erickson and Kim Paus
-Introduction and Background
-Experiment Setup
-Results and Discussion
-Application
-Conclusion

Questions
• Contact Information:
Joel Morgan
St. Anthony Falls Laboratory
2 3 rd Ave SE
Minneapolis, MN 55414
morga526@umn.edu