1

Selected Summaries of Recent and On-Going Projects

Contents 1. Stormwater Non-potable Beneficial Uses and Effects on Urban Infrastructure, Water Environment Research Foundation and US EPA, 2009 – 2012 ........................................................................................... 1

1.1 Groundwater Impacts from Seepage Wells used for the Disposal of Stormwater ............................ 2

2. Field Monitoring of Up-Flo Filter - Bama Belle Site, HydroInternational, 2009 – 2013 ............................ 4

3. Identification and Treatment of Emerging Contaminants in Wet Weather Flows, US Environmental Protection Agency, 2007 - 2013 .................................................................................................................... 6

4. Environmental Contamination Sensor Development and Evaluations Associated with Natural Disasters; NSF and the Center for Optical Sensors and Spectroscopies (COSS), University of Alabama at Birmingham, 2008 – 2014 ............................................................................................................................. 8

4.1 PAH Contamination from Newly Paved Surfaces ............................................................................. 11

4.2 Heavy Metal Releases from Alternative Drainage System Components .......................................... 11

4.3 Urban Wildlife Bacteria Sources and Survival in the Environment ................................................... 12

5. Biofiltration Media Evaluation; Geosyntec Consultants and Boeing Co., 2008 – 2012 .......................... 13

5.1 Enhanced Underdrain Systems for Biofilters .................................................................................... 16

6. National Demonstration of Advanced Drainage Concepts using Green Solutions for CSO Control; US EPA and TetraTech, 2008 – 2013 ................................................................................................................ 18

6.1 Stormwater Controls to Satisfy Developing Regulations .................................................................. 21

7. National Stormwater Quality Database, US EPA, 2001 – 2011 ............................................................... 25

8. Detection and Corrections of Inappropriate Discharges to Stormwater Drainage Systems, US EPA, 2001 – 2008 ................................................................................................................................................ 25

9. Relationships Between the Variability of Stormwater Characteristics and Development Characteristics .................................................................................................................................................................... 25

10. Heavy Metal Contamination of Soils in Treated Wood Burn Areas ...................................................... 26

11. Stormwater Quality Modeling .............................................................................................................. 28

12. Compaction of Urban Soils .................................................................................................................... 28

1. Stormwater Non-potable Beneficial Uses and Effects on Urban Infrastructure, Water Environment Research Foundation and US EPA, 2009 – 2012 The examination of stormwater beneficial uses involves a number of steps and tools. This project shows how currently available models and other tools can be interactively used to calculate the quality and quantity benefits of stormwater reuse. Besides the obvious benefit of reduced stormwater discharges (and attendant receiving water benefits), many reuse options also benefit other components of the urban water infrastructure. If stormwater is stored and used to irrigate landscaped areas and flush

2

toilets, as is common in many locations today, less highly treated domestic water needs to be delivered. Grey water systems, where partial treatment of some household wastewaters allows that water to be used for non-potable use, also results in smaller sanitary wastewater sewage collection and treatment systems. General household water conservation also has been shown to reduce wastewater discharges, in addition to reducing domestic water deliveries. Firefighting water demands usually requires the construction of much larger water lines than needed to supply in-building uses. In earthquake-prone areas, on-site storage of firefighting water in stormwater wet detention ponds has been shown to be more reliable than the municipal water supply system. In many areas of Western Europe, large-scale infiltration of stormwater has been demonstrated to dramatically reduce the volumes of combined sewage needing treatment during wet weather. In Japan, infiltration of stormwater, initially used to also reduce CSO problems, has also been shown to have dramatic benefits on local groundwater recharge.

1.1 Groundwater Impacts from Seepage Wells used for the Disposal of Stormwater One of the case studies being examined as part of this WERF project is located in Millburn, NJ. Dry wells/seepage pits have been used since 1999 on new construction (and extensive remodeling) of homes in Millburn, NJ, to infiltrate the additional runoff associated with the new construction. An EPA demonstration project is examining the effectiveness of these infiltration devices in reducing discharges to the storm drainage system, and to document any problems associated with their use. Millburn has separate sewers, but there is concern about drainage problems developing in areas of new construction. About 1,500 homes have drywells and some of these also have tanks before the drywells for irrigation reuse withdrawals. The groundwater table is as shallow as 8 to 10 ft along the river in town. The soils vary greatly in the community, with a lot of clayey soils. Our WERF project used the basic information and data and conducted further analyses and modeling.

Peerless Concrete Products, Butler, NJ supplies the dry wells to many of the sites in Millburn (photo from http://www.peerlessconcrete.com/)

Installed drywell in Millburn, NJ, showing the surrounding stone, before completion of the backfilling

3

Underground water storage cistern in Millburn, NJ

Pump for irrigation system

Modeling showed that the cisterns provide an overall runoff reduction of about 24% for each home. Because of the relatively poor soils in the area and the large amounts of landscaping for the large lots, most of the runoff originates from the small landscaped areas that are not treated by these controls. The natural runoff from this area is also relatively high due to the soils. When compacted during the construction activities and general land use activities, soils with some clay become quite impermeable. These drywells provide much of their infiltration benefits at lower depths that are not subjected to the compacted.

Monitored water levels in dry well in Millburn, NJ.

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2. Field Monitoring of Up-Flo Filter - Bama Belle Site, HydroInternational, 2009 – 2013 Treatment of stormwater requires a device that can remove many types of pollutants as well as large amounts of debris and floatable materials, over a wide range of flows. Filtration is one tool being used in many areas to remove a wide range of stormwater pollutants. The objective of this research is to examine the removal capacities of a recently developed stormwater filtration device, in part developed by engineers at the University of Alabama through a Small Business Innovative Research (SBIR) grant from the U.S. Environmental Protection Agency. The Up-Flo® Filter is an efficient high-rate stormwater filtration technology designed for the removal of trash, sediments, nutrients, metals and hydrocarbons from stormwater runoff. Compared with the traditional downflow filtration treatment, the upflow filtration method reduces clogging and was developed to remove a broad range of stormwater pollutants, especially those associated with particulates. The high flow rate capacities of the Up-Flo® Filter are accomplished through controlled fluidization of the filtration media, while still capturing very small particulates through a flexible, but constraining, media container. The Up-Flo® Filter also drains down between rain events which minimizes anaerobic conditions in the media and which also partially flushes captured particulates from the media to the storage sump, decreasing clogging and increasing run times between maintenance. Gross floatables are captured through the use of an angled screen before the media and a hood on the overflow siphon, while the sump captures bed load particulates. The full-sized Up-Flo filter is being tested with six modules in Tuscaloosa, AL. A 7-foot tall 4-foot diameter Up-Flo TM Filter has been installed at the Riverwalk parking lot near the Bama Belle on the Black Warrior River. The system receives surface runoff from a 1 acre site that includes a parking lot, driveways, sidewalks, and a small landscaped area. The system was installed for the purpose of determining the hydraulic capacity and the pollutant removal capabilities in a full-scale field installation under both controlled and actual runoff conditions.

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Flow paths in the Up-FloTM filter (HydroInternational drawing).

Cut-away of an installed Up-FloTM filter (HydroInternational drawing).

Interior of monitoring box (without samplers, but with batteries, data recorders, and sondes).

Flow vs. head graph for CPZ media indicating high treatment flow rates for small filter areas.

Head (in) vs. Flow Rate for CPZ Media (gal/min)

y = 6.9449x

R2 = 0.6918

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Head (in)

Flo

w R

ate

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Upper Confidence in 95% Lower Confidence in 95%

Actual Data Linear (Actual Data)

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UpFlo filter performance during controlled tests.

Probability plots showing significant removal of very small particles.

3. Identification and Treatment of Emerging Contaminants in Wet Weather Flows, US Environmental Protection Agency, 2007 - 2013 The presence of emerging contaminants (ECs) in wet weather flows (WWFs) has not been well-documented, while there has been extensive efforts investing these compounds in wastewater discharges, water systems, and in natural waters. The initial project activities focused on an extensive literature review of emerging contaminants in wet weather flows, specifically separate stormwater, combined sewer overflows (CSOs), and sanitary sewer overflows (SSOs). Characterization (presence and concentrations) of ECs in wet weather flows and on their treatment is of the most concern for this project. Although little information exists for separate stormwater, much more exists for sanitary wastewaters and surface waters. This information allowed us to identify which constituent categories are likely present in wet weather flows, and in what concentrations. Much information exists for treatment of ECs in municipal wastewater treatment facilities, and in public water treatment plants. From this literature information, we are developing a simple screening tool that will consider the likely presence of the different ECs in the three WWFs of interest, and their treatability by typical and advanced unit processes applicable to WWFs.

Influent

After primary treatment

7

After secondary treatment

Final effluent

Tuscaloosa Wastewater Treatment Plant PAHs during rain event #1. The following are some of the pharmaceutical and personal care products (PPCPs) for which our project team have developed analytical methods for contaminated surface waters. We are evaluating selected compounds in our analytical scheme: Ibuprofen Diltiazem hydrochloride Gemfibrozil 5,5-Diphenly hydentoin Divalproate sodium Dichlofenac Caffeine Trimethoprim Triclosan In addition, estrogen, common veterinary medications, along with some lotions and fragrances are being added to our list, depending on reported frequency and concentrations from the literature, and the likelihood of their presence in WWFs. The analyses of characterization samples are being conducted using HPLC and GC/MSD. Pesticides are being analyzed using GC/ECD, while heavy metals are being examined using a variety of methods (ICP and ICP/MS). The analytical scheme includes sampling at a wastewater treatment plants during wet weather. The treatment plant is a separate sanitary sewage treatment facility, but is affected by typical infiltration and inflow, or I&I during large flows. Source area samples in different land uses are also being collected. About 50 source area sheetflow samples are being collected during many different rains. Four locations at the wastewater treatment facilities are also being sampled during seven rains and seven dry weather periods. This information, along with specialized laboratory tests, is being used to identify treatability of the ECs found in wet weather flows.

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Influent

After primary treatment

After secondary treatment

Effluent

HPLC analyses for other organic ECs for first event at the Tuscaloosa treatment plant. Compounds commonly identified include the acidic pharmaceuticals sulfamethoxole, trimethoprim, carbamezapine, and fluoxetine.

4. Environmental Contamination Sensor Development and Evaluations Associated with Natural Disasters; NSF and the Center for Optical Sensors and Spectroscopies (COSS), University of Alabama at Birmingham, 2008 – 2014 The mission of the Center for Optical Sensors and Spectroscopies (COSS) is to promote optical sensing and spectroscopy research on environmental, biomedical, and national security issues through

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15

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13

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41

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0

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46

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43

00

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77

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66

33

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98

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2

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61

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7

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0

28

70

32

5

24

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30

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72

0

25

.46

8

31

74

83

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50

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1

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.65

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33

79

67

27

.09

6

34

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94

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35

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0

36

61

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4

28

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SPD-M20A-263 nm

0510Influ010116Acid

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97

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50

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90

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15

.11

2

5

19

46

23

15

.53

6

6

10

05

92

4

16

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6

7

17

68

87

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0

8

64

36

25

17

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9

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51

5

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8

10

11

31

61

7

18

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56

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18

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2

13

70

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31

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78

22

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12

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2

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28

.00

8

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44

13

3

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4

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43

2

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55

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59

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26

22

9

23

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11

63

7

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13

09

7

25

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70

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01

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73

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37

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2

38

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9

collaborative use of resources and expertise among the member universities, government and industrial laboratories, and improve sensor techniques using recently developed revolutionary laser and spectroscopic technologies. The Deep Water Horizon oil spill off of the southeast coast affecting LA, MS, AL, and FL has highlighted the critical need for rapid environmental monitoring of hazardous wastes and other pollutants. In the last year, COSS environmental researchers associated with the Environmental Institute at UA have been developing and testing methods that can be used to rapidly detect the extent of contamination of spills and discharges of hazardous organic compounds. This work is also investigating the problems associated with the aftermath of these accidents such as determining the potential hazards to responders and residents of the affected areas. Long-term potential contamination of aquatic organisms and the food supply is also of concern that can be better examined using the newly developed methods. The COSS laser-based “optical nose” being developed as part of this NSF-supported research will enable rapid and sensitive measurements of these compounds during, and after, these types of environmental disasters. Our on-going research as part of our COSS activities has been to investigate the sources, fate, and treatment of toxicants, including organic contaminants of most interest to the COSS laser facility. We focused on a wide range of materials, from PAHs and other petroleum hydrocarbons, to heavy metals, and radioactive materials. The work with the organic compounds will enable us to develop and test analytical methods that can be used in times of environmental disasters or homeland security incidents, specifically to obtain rapid data that is currently not available. We initiated this research direction in the aftermath of several severe hurricanes in the gulf coast a few years ago. The unfortunate major oil spill in the gulf is another example of the dramatic need for rapid and reliable information. As part of this effort, we acquired a scanning FTIR spectrophotometer and developed methods to obtain analytical spectra in the range of interest to the COSS laser instrumentation during exposure experiments to quantify losses of critical organic contaminants to the environment, and several very successful outreach activities conducted in conjunction with other NSF projects. The most common IR wavelengths used for analytical purposes for the organic compounds of interest fall outside of the 2 µm (5,000 cm-1) to 3.6 µm (2,800 cm-1) operational range of infrared laser instrumentation. Secondary wavelengths exist in this range, but have not been well documented in the literature. Most of the compounds investigated during the method development phase involved solvents, as shown below for MEK. Research was expended to investigate heavier hydrocarbons and crude oil.

Perkin Elmer Spectrun Rx 1 scanning FTIR

FTIR scan of Methyl Ethyl Ketone in the range of 2000 to 4500 cm-1

10

We are also working with Miles College in Birmingham to develop methods using their HPLC and GC/MS equipment to simultaneously quantify the organic compounds that we are investigating during our exposure experiments. Exposure experiments examined the releases of toxic PAH compounds from different asphalt mixtures during the first several months of use, the period when we expect most of these releases to occur. Fate modeling of the organic compounds of interest is used to identify which are likely to cause the most harmful effects, and which can be treated by conventional and advanced wastewater and water treatment methods. The fate of discharged or spilled contaminants was also investigated using fugacity modeling verified by field investigations.

GC/MSD chromatograph showing large concentrations of several compounds of interest (especially phenanthrene, benz[a]anthracene, indeno[1,2,3-c,d]pyrene, and dibenzo[a,h]anthracene).

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4

mVo

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0 0.00

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hene

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5 1.98

9

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rene

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nthr

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e 37.5

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sene

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5 3.50

1

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o[b]

fluor

anth

ene 4.

505 6.

424

Benz

o[k]

fluor

anth

ene 1.

115 1.

590

(Ben

zo[a

]pyr

ene)

0.00

0 BD

L 0.00

0 BD

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Inde

no[1

,2,3

-c,d

]pyr

ene 1.

827 2.

606

0.00

0 0.00

0

0.00

0 0.00

0

0.00

0 0.00

0

0.00

0 0.00

0

Dibe

nzo[

a,h]

anth

race

ne

1.11

2 1.58

5

0.00

0 0.00

0

Benz

o[g,

h,i]p

eryle

ne

1.58

6 2.26

2

FID

PAHStd09290320A

Name

ESTD concentration

NORM concentration

HPLC at Miles College used to quantify emerging organic contaminants

129630

99.9

99

95

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Effects and interactions on Nystatin migration in vadose zone (rainfall and intrinsic permeability most significant, interacting together and separately)

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One example of an experiment being conducted as part of this research is briefly described below:

4.1 PAH Contamination from Newly Paved Surfaces These tests were performed under actual environmental conditions to examine the organic and heavy metal content of runoff from newly installed asphalt pavements and to observe changes in their concentrations with aging during the first several months of exposure. During the life of a pavement, it undergoes aging and hardening due to exposure to temperature, air, and moisture in the environment. This results in the loss of some pavement components by volatilization and irreversible changes in composition by reaction with atmospheric oxygen. Asphalt contains PAHs and heavy metals that represent potential contaminants in water runoff. In addition to PAHs and metals, nutrients, other organic and inorganic toxicants also leach into the runoff when rain water comes in contact with the pavement surface. This study focused on the changes in leaching of these compounds (PAHs, the heavy metals Cd, Cr, Cu, Pb and Zn, and selected nutrients and toxicity) of the runoff from the pavement during initial pavement aging, a period when the most rapid changes occur, and when the runoff is expected to be the most toxic.

4.2 Heavy Metal Releases from Alternative Drainage System Components The goal of this research is to determine: (1) how contaminants in pipe materials affected the quality of the water and to identify the environmental parameters causing degradation of the material, contact time, and interactions of these factors, and (2) contributions of roof runoff contamination caused by atmospheric deposition. The contaminants being studied include heavy metals, toxicity, nitrates, and phosphates. Prior research has been performed on the contributions of rooftop material to runoff water quality. Results show that the roof runoff quality is dependent on the type of roofing materials used. Little data is available to indicate how piping materials and environmental parameters influence storm water quality. This on-going research is investigating long-term leaching of these compounds from several gutter materials (galvanized aluminum, vinyl, copper, and galvanized steel) and pipe materials (concrete, high-density polyethylene, poly vinyl chloride, and galvanized corrugated steel). Full-sized samples of these materials are being soaked in buffered low and high pH test solutions, at high and low conductivity, with water samples withdrawn every few days for analyses.

Copper roof drains and downspouts

Vinyl roof drains and downspouts

Concrete is the most common currently used piping material

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Total zinc concentrations in containers with river water.

4.3 Urban Wildlife Bacteria Sources and Survival in the Environment As noted above, additional research tasks during this emerging contaminant project are examining sources and movement of urban area bacteria. Sewage-borne pathogen contamination of urban receiving waters constitutes risk to health. Risks have traditionally been evaluated on the basis of indicator species, microorganisms assumed to have come from sanitary-sewage contamination of the watershed and assumed to indicate the presence of sewage-borne pathogens. Sources other than sewage (e.g., animal feces and soil storage) also contribute to indicator-species assemblages in urban runoff. Accurate assessment of health risk from runoff requires knowledge of these other sources. This research component is analyzing the non-sewage components of microbial indicator species from source areas of various land uses, the potential for mobilization of those species into sheetflow by rainfall, and the particle/surface associations likely to affect transport of those species through the watershed.

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Survival of E. coli under varying environmental conditions. Warm, wet, and dark conditions allow the bacteria to thrive compared to other conditions which result in much greater reductions of their populations.

5. Biofiltration Media Evaluation; Geosyntec Consultants and Boeing Co., 2008 – 2012 This study investigated a variety of media types that can be used singly and in combination for use in stormwater treatment facilities, including media filters, biofilters, bioretention, rain gardens, etc. These tests were conducted specifically to determine the different media performance options for use in advanced biofiltration systems at an industrial site having very stringent numeric effluent limits. These stormwater treatment systems were designed to treat 90% of the long-term runoff volume from drainage areas ranging from 5 to 60 acres at the site. The main pollutants of interest for the project are cadmium, copper, lead, and dioxins, with other constituents being of secondary interest, based on historic stormwater quality monitoring results at the site. One primary project objective is for treated effluent concentrations to meet the low numeric effluent limits that have been applied to stormwater discharges through the site’s NPDES permit. These numeric effluent limits are based on water quality standards. A challenge to the project design is that current site runoff concentrations for the pollutants of interest are generally below levels typically seen in urban and industrial stormwater runoff. A review of the literature on filtration media and onsite monitoring data (including existing treatment system performance results and previous media pilot testing studies) indicated that several promising media exist for consistently treating the pollutants of interest to the required effluent concentrations. However, many of these materials are very expensive; with potential construction costs being significant given the large volumes required for the systems based on early designs (estimated media volumes for the project have ranged from 5,000 – 12,000 cubic yards). There are newly available materials that are promising, but little, if any, data are available to quantify their performance. These tests therefore

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evaluated these candidate materials under procedures that have proven successful during past media investigations for stormwater treatment effectiveness.

Observed infiltration and clogging characteristics for tested media.

Media mixtures performed more consistently under a broader range of conditions than individual components used separately. The mixtures capitalize on the pollutant removal strengths of their components, while providing other components that may address the weaknesses (such as the release of cations in large concentrations during ion exchange). The media mixtures that are most robust (longest run times before clogging, with moderate flow rates and suitable contact times for pollutant removal) are: Rhyolite sand, SMZ, and GAC mixture (blended mixture) and the Rhyolite sand, SMZ, GAC-PM

mixture (blended mixture). They had very similar performance attributes. The added peat provided some additional benefits for metal reductions at high flow rates. The GAC in these mixtures (when mixed with the other components) also provided better control for a number of other constituents, including nitrates.

Site filter sand-GAC-site Zeolite (layered) clogged earlier, but possibly would have fewer exceedences overall. The drawback to the layering of the filter components is the change in flow rate and contact time.

In terms of statistically significant removals, both R-SMZ-GAC and S-Z-GAC (layered) media combinations performed similarly, although the current site layered media combination did not demonstrate

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statistically significant removals for lead. Any media combination that included GAC was effective for TCDD removal. All of the media tested had very high levels (approaching 90%) of removals of particulates, even down to very small particle sizes (as small as 3 µm), with concurrent good removals of pollutants strongly associated with the particulates (such as for total aluminum, iron, and lead).

Media performance plots for copper from long-term, full-depth column tests. Some constituents and some media required a certain contact time before retention, while others were more capable of pollutant retention more rapidly and at lower influent concentrations. For example, when the contact time was less than 10 minutes, the metal removals were much less than for the longer contact times. Also, greater contact with GAC resulted in slightly better nitrate removals, while the greater contact time for phosphate resulted in greater losses of the phosphate from the media. This type of trade-off between improved removal and increased leaching was seen for several media-constituent combinations. Longer retention times can be achieved through deeper media beds or slower flow rates and larger surface areas. The column tests confirmed generally the results of the laboratory studies that showed that good removals could be achieved with relatively slow to moderate flow rates (5 to 60 meters/day) and moderate contact times of the water with the media (10 to 40 minutes).

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Media performance plots for lead from varying-depth column tests. The GAC was the most important component in these mixtures, while the addition of either of the zeolites was also needed. The specific choice of which would be dependent on costs and specific ion exchange issues. The sand is critical to moderate the flow rates and to increase the contact times with the coarser media, unless other flow controls were used in the filter designs. The Rhyolite sand added some removal benefits compared to the site sand. As noted, a small amount of peat added to the mixture increases metal removals during high flow rates. Therefore, the best mixture for removal of pollutants to levels that met the effluent discharge limits was the combination of Rhyolite sand (30%), surface modified zeolite (30%), GAC (30%), and approximately 10% peat. To minimize the leaching of constituents from the GAC, its concentration could be reduced, but then nitrate removals would be limited.

5.1 Enhanced Underdrain Systems for Biofilters The treatment of stormwater by biofilters is dependent on the hydraulic residence time in the device for some critical pollutants. The effective use of biofilters for the control of stormwater in combined sewered areas is also related to residence time, as it is desired to retain the water before discharge to the drainage system in order to reduce the peak flows to the treatment plant. This research is conducting a series of tests to determine the hydraulic characteristics of sand-based filter media (having a variety of particles sizes representing a range of median particle sizes and uniformity coefficients) during pilot-scale trench tests. The drainage rate in biofiltration devices is usually controlled using an underdrain that is restricted with a small orifice or other flow-moderating component. These frequently fail as the orifices are usually very small (<10 mm) and are prone to clogging. A series of tests were also conducted using a newly developed foundation drain material (SmartDrainTM) that offers promise as a low flow control device with minimal clogging potential. A pilot-scale biofilter using a trough 3m long and 0.6 x 0.6m in cross section is being used to test the variables affecting the drainage characteristics of

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the underdrain material (such as length, slope, hydraulic head, and type of sand media). Current tests are also being conducted to test the clogging potential of this drainage material.

SmartDrainTM installed in pilot-scale biofilter.

The results from the experiments conducted to test the variables affecting the drainage characteristics of the filter media indicate that slope of the SmartDrainTM material had no significant effect on the stage-discharge relationship whereas effect of length of the SmartDrainTM material had a very small effect on the discharge. Research is ongoing to investigate the clogging potential of the SmartDrainTM material. Only about 20% reductions in the outflow rate of the filter media have been observed during the clogging tests having a total load of about 40 kg/m2 onto the filter area, about twice the load that can usually cause clogging of biofilter media.

Reduction in flow with increased sediment loading.

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SmartDrainTM flow rates compared to very small orifices. Turbidity (NTU) measurements showed that the effluent NTU decreased rapidly with time, indicating significant retention of silt in the test biofilter during the clogging tests. These preliminary tests indicate that the SmartDrainTM material provides an additional option for biofilters, having minimal clogging potential while also providing very low discharge rates.

6. National Demonstration of Advanced Drainage Concepts using Green Solutions for CSO Control; US EPA and TetraTech, 2008 – 2013 The Kansas City demonstration project on the use of “green infrastructure” to minimize combined sewer overflows (funded by the US EPA and supported by a wide range of national and local agencies) uses a variety of integrated practices and modeling approaches. “Green infrastructure” includes a wide variety of stormwater runoff volume and pollutant reduction tools that can be applied in existing urban areas. Those being examined during this project include beneficial use of runoff, rain gardens, and biofilters. This extensive project is collecting data before, during, and after implementation of a variety of control practices in a 100 acre test watershed, and in a parallel control site. The reduction of discharges to the drainage system during wet weather will be calculated using models and verified through field monitoring. The continuous models determine the decreased amount of stormwater discharged for each event as the storage and infiltration facilities dynamically fill and drain over an extended period of time. Both developed stormwater and combined sewersheds can benefit from the added storage from areas retrofitted with bioretention cells or rain gardens and other management practices, e.g., inlet retrofits or curb-cuts with tree plantings.

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Kansas City curb cut biofilter with monitoring station.

Kansas City porous concrete sidewalk in study area.

The overall key project objectives are to:

Demonstrate the integration of green solutions with traditional gray infrastructure in an urban-core neighborhood having a combined sewer system

Develop a methodology for implementation of Green Solutions

Measure the changes in the peak flow, total volume and pollutant mass of storm events in the receiving system or the reduction of combined wastewater volumes, pollutant loads and overflows

Develop a model for predicting the quality and quantity benefits of implementing Green Solutions

Compare economic costs and benefits of integrated green and gray solutions

Percentage reduction in annual runoff from directly connected roofs with the use of rain gardens.

Reduction of annual runoff from directly connected roofs with the use of runoff storage and irrigation.

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The watershed model (WinSLAMM) and the sewerage model (SWMM) are being calibrated for this area using the pre-construction flow and water quality data. Both dry and wet weather flow data are being recorded. The calibrated models were used early in the project to predict the benefits of the upland controls, and these predictions are being verified as the controls are installed. After the models are calibrated and verified for the demonstration area, they will be used to predict the benefits of wider application of the upland controls across the city. Specifically, the models will predict the decreased runoff volumes and peak runoff rates associated with upland stormwater controls to alleviate problems in the combined sewer system. Water quality benefits associated with stormwater pollutant discharge reductions of wet-weather flow particulates (including particle size distributions), nutrients, bacteria, and heavy metals are being quantified. WinSLAMM is used to calculate the stormwater contributions to the combined sewerage system during wet-weather by providing a time series of flows and water quality conditions, for various types of upland controls, while SWMM, with its detailed hydraulic modeling capabilities, focuses on the interaction of these time series data with the sewerage flows and detailed hydraulic conditions in the drainage system. Both models will be used interactively emphasizing their respective strengths. The land survey found that about 65% of the area is landscaped, with most being in turf grass in poor to good condition. This information was used in conjunction with regional evapotranspiration data to calculate the amount of supplemental irrigation needed to meet the ET requirements of typical turf grass, considering the long-term rainfall patterns. Most of the supplemental irrigation would be needed during the months of July and August, while excess rainfall occurs in October through December (compared to ET requirements during these relatively dormant months). A single 35 gallon rain barrel per home is expected to reduce the total annual runoff by about 24% from the directly connected roofs, if the water use could be closely regulated to match the irrigation requirements. If four rain barrels per home were used (such as one on each corner of a house receiving runoff from separate roof downspouts), the total annual volume reductions could be as high as about 40%. Larger storage quantities result in increased beneficial usage, but likely require larger water tanks. Water use from a single water tank is also easier to control through soil moisture sensors and can be integrated with landscaping irrigation systems for almost automatic operation. A small tank about 5 ft in diameter and 6 ft in height is expected to result in about 75% total annual runoff reductions, while a larger 10ft diameter tank 6 ft tall could approach complete roof runoff control. The use of rain barrels and rain gardens together at a home is more robust than using either method alone: the rain barrels would overflow into the rain gardens, so their irrigation use is not quite as critical. In order to obtain reductions of about 90% in the total annual runoff, it is necessary to have at least one rain garden per house, unless the number of rain barrels exceeds about 25 (or 1 small water tank) per house. In that case, the rain gardens can be reduced to about 80 ft2 per house.

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Reduction in annual runoff from directly connected roofs with the use of rain gardens and roof runoff storage and irrigation.

The “best” combination of control options is not necessarily obvious. The CSO program must meet their permit requirements that specify certain amounts of upland storage in the watershed. Other elements, including costs, aesthetics, improvements to street-side infrastructure, and other benefits, also need to be considered in a decision analysis framework.

6.1 Stormwater Controls to Satisfy Developing Regulations Newly proposed stormwater regulations being promulgated by state and federal regulatory agencies are stressing significant reductions in runoff volumes for new development, even areas of poor soils. Many of the above research projects, along with our past research results, have been incorporated into stormwater management models and demonstration projects that can show how these regulations can be addressed. However, it is important that various precautions are considered in challenging conditions. The Energy Independence and Security Act of 2007” was signed into Law on Dec. 19, 2007. Title IV (“Energy Savings in Building and Industry”), Subtitle C (“High Performance Federal Buildings”) Sec. 438 (“Storm Water Runoff Requirements for Federal Development Projects”) requires that: “The sponsor of any development or redevelopment project involving a Federal facility with a footprint that exceeds 5,000 square feet shall use site planning, design, construction, and maintenance strategies for the property to maintain or restore, to the maximum extent technically feasible, the predevelopment hydrology of the property with regard to the temperature, rate, volume, and duration of flow.” This new provision requires much more attention to controlling runoff volume, in addition to other hydrologic features. Current proposed state regulations require runoff volume restrictions so that post-development runoff volumes meet pre-development runoff volumes for the 2-year rainfall (about 4 inches for the central Alabama area). Our past research has examined regional soils and how they may affect infiltration capacity:

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Loss of infiltration capacity due to soil disturbance and compaction during construction. We have also researched groundwater contamination potential for stormwater infiltration. Potential groundwater problems are affected by a stormwater pollutant’s abundance in the stormwater, its mobility through the unsaturated zone above the groundwater, and the treatment received before infiltration. Basically, with surface infiltration with minimal pretreatment (grass swales or roof disconnections), mobility and abundance are most critical. With surface infiltration with sedimentation pretreatment (treatment train: sedimentation then media filtration), mobility, abundance, and treatability are all important. With subsurface injection with minimal pretreatment (porous pavement in parking lot or dry well), only abundance affects groundwater contamination potential. We have found that infiltration devices should not be used in most industrial areas without adequate pretreatment. Runoff from critical source areas (mostly in commercial areas) need to receive adequate pretreatment prior to infiltration. However, runoff from residential areas (the largest component of urban runoff in most cities) is generally the least polluted and should be considered for infiltration. Considerations for the use of porous pavement in Central Alabama:

• Soils having at least 0.1 in/hr infiltration rates can totally remove the runoff from porous pavement areas, assuming about 1 ft coarse rock storage layer. Porous pavement areas can effectively contribute zero runoff, if well maintained.

• However, slow infiltrating soils can result in slow drainage times of several days. Soils having infiltration rates of at least 0.5 in/hr can drain the pavement structure and storage area within a day, a generally accepted goal.

• These porous pavements can totally reduce the runoff during the intense 2-year rains. • Good design and construction practice is necessary to prolong the life of the porous pavements,

including restricting runon, prohibiting dirt and debris tracking, and suitable intensive cleaning. Considerations for the use of green roofs in Central Alabama:

• Green roofs can contribute to energy savings in operation of a building, can prolong the life of the roof structure, and can reduce the amount of roof runoff.

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• They can be costly. However, they may be one of the few options for stormwater volume control in ultra urban areas where ground–level options are not available.

• Irrigation of the plants is likely necessary to prevent wilting and death during dry periods.

Annual roof runoff reductions for local green roofs.

• Vegetated green roofs can reduce up to about 70% of the annual roof runoff during typical conditions, if the complete roof is planted.

• The plants would likely wilt and die as the evapotranspiration (ET) drives the substrate to the plants’ wilting point during the late summer, early fall period, requiring substantial irrigation.

Considerations for the use of rain gardens for controlling roof and paved area runoff in Central Alabama:

• Simple rain gardens with extensive excavations or underdrains can be used near buildings for the control of roof runoff, or can be placed in or around the edges of parking areas for the control of runoff from parking areas.

• Rain gardens provide greater groundwater contamination protection compared to porous pavements as the engineered soil fill material should contain significant organic material that hinders migration of many stormwater pollutants. This material also provides much better control of fine sediment found in the stormwater.

• Rain gardens can be sized to control large fractions of the runoff, but maintenance to prevent clogging and to remove contaminated soils is also necessary.

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Annual runoff reductions from paved areas or roofs for different sized rain gardens and soils.

• Local rain gardens should be located in areas having soil infiltration rates of at least 0.3 in/hr. Lower rates result in very large and much less effective rain gardens, and the likely clay content of the soil likely will result in premature clogging.

• Rain gardens should be from 5 to 10 percent of the drainage area to provide significant runoff reductions (75+%).

• Rain gardens of this size will result in about 40 to 60% reductions in runoff volume from the large 4 inch rain. Rain gardens would need to be about 20% of the drainage area in order to approach complete control of these large rains.

• Roof runoff contains relatively little particulate matter and rain gardens at least 1% of the roof area are not likely to clog (estimated 20 to 50 years).

• Paved area runoff contains a much greater amount of particulate matter and would need to be at least 10% of the paved area to have an extended life (>10 years).

Newly published federal construction site and stormwater regulations will require much more careful site planning. Runoff volume controls during large events will require extensive use of infiltration practices. The sizes of practices for the same land use is not very sensitive to soil conditions (less runoff increases compared to pre-development conditions with poorer soils and therefore lower volume reduction goals). However, use of infiltration controls in poor soils is not a very robust/sustainable practice, and needs to be done with caution and over-sizing.

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7. National Stormwater Quality Database, US EPA, 2001 – 2011

8. Detection and Corrections of Inappropriate Discharges to Stormwater Drainage Systems, US EPA, 2001 – 2008

9. Relationships Between the Variability of Stormwater Characteristics and Development Characteristics Urban land uses and their associated impervious cover increase the quantity and worsen the quality of stormwater runoff seriously impairing receiving waters. However, there is substantial variability in the measured impervious covers, even within single land use areas. This research is investigating this variability in relationship to the variability measured in stormwater quality. In order to determine how land development variability affects the quantity and quality of runoff, different land surfaces (roofs, streets, landscaped areas, parking lots, etc.) for different land uses (residential, commercial, industrial, institutional, etc.) can be directly measured. This research examined 125 neighborhoods located in the Little Shades Creek watershed (Jefferson County, near Birmingham, AL) and 40 neighborhoods located in five highly urbanized drainage areas situated in Jefferson County, AL (in and near city of Birmingham), along with stormwater quality data from the local stormwater monitoring program. A locally calibrated version of the Source Loading and Management Model (WinSLAMM) was also used to calculate the runoff quantity and quality for six highly urbanized drainage areas and to examine the performance of different combinations of stormwater control devices. The research is determining the most suitable methods for stormwater control based on variability in land uses, land development, and rain characteristics.

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Average source covers for high density residential areas.

Variabilities in measured directly connected impervious cover by land use.

For small rain depths, almost all the runoff and pollutants originate from directly connected impervious areas, as disconnected areas have most of their flows infiltrated. For larger storms, both directly connected and disconnected impervious areas contribute runoff to the stormwater drainage system. In many cases, pervious areas are not hydrological active until the rain depths are relatively large and are not significant runoff contributors until the rainfall exceeds about 25 mm for many land uses and soil conditions. However compacted soils can greatly increase the flow contributions from pervious areas during smaller rains. Urbanization radically transforms natural watershed conditions and introduces impervious surfaces into the previously natural landscape. Total impervious areas are mostly composed of rooftop and transportation related components that can be either directly connected or disconnected to the drainage system. The impervious areas that are directly connected to the storm drainage system are the greatest contributor of runoff and stormwater pollutant mass discharges under most conditions.

10. Heavy Metal Contamination of Soils in Treated Wood Burn Areas This research examined the contamination of soils in areas where building debris were burnt in fires as a trash disposal practice. The presence of treated wood in the fires greatly contaminated the soils with heavy metals. This research examined the metal species that were leached from the soil. Arsenic, chromium, and copper species leached from the ash of burned wood which has been treated with chromated copper arsenate preservative were the major focus of this investigation. The research encompasses a study of the composition and reactivity of soils, wood ash, and the sorption mechanisms which immobilize and precipitate metal species. In particular, the research has shown positive results regarding the feasibility of reducing the mobility of metal species by the addition of agricultural soil amendments that will increase the natural attenuation ability of soils. Additional investigations involve

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the testing of enhanced agricultural amendments that will have the ability to further increase the natural attenuation of soils and therefore reduce the mobility of rainwater‐leached metal species from these areas.

Column leaching test full-factorial experimental setup for examining metal migration from contaminated soils at burn sites.

The use of agricultural gypsum retarding leaching of arsenic from contaminated soils.

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Of the mixtures studied, the CaSO4 (gypsum) amendment acting alone was found to be the most effective amendment for the overall retardation of Cr and As mobility. The CaSO4/AgLime combination was a close second in As and Cr reduction. CaSO4 as a reactive soil amendment for the treatment of soils containing Cr and As metals results in significant rates of reduction of metals mobility, approaching 80% compared to unamended soil/CCA-ash mixtures over a simulated one-year leaching period. An optimization study revealed that a ratio of 3:1 of CaSO4 to metals mass was most effective in reducing the mobility of Cr and As metals. Use of a higher ratio would serve as a source for Ca+2 ions and should guarantee long-term stabilization while maintaining the pH in the 7.3-8.0 range.

11. Stormwater Quality Modeling

12. Compaction of Urban Soils