Control

Day Replicates

1 2 3 4 5 6 7 8 9 10

1 A A A A A A A A A A

2 A A A A A A A A A A

3 A A A A A A A A A A

4 6 4 5 4 5 4 5 6 4 5

5 12 10 12 13 10 11 12 11 10 9

6 A A A D A A A A A A

7 21 22 19 D/21 23 22 20 19 18

Totl

There is one of these tables for each concentration in the test (Control, 6.25, 12.5,25, 50, 100.

Control

Day Replicates

1 2 3 4 5 6 7 8 9 10

1 A A A A A A A A A A

2 A A A A A A A A A A

3 A A A A A A A A A A

4 6 4 5 4 5 4 5 6 4 5

5 12 10 12 13 10 11 12 11 10 9

6 A A A D A A A A A A

7 21 22 19 D/21 23 22 20 19 18

Totl 39 36 36 D/17 D/36 38 39 37 33 32

There is one of these tables for each concentration in the test (Control, 6.25, 12.5,25, 50, 100.

Pimephales promelas Survival

Replicates

Percent Effluent Rep 1 Rep 2 Rep 3 Rep 4

Control 100 100 100 100

6.25% 100 100 100 100

12.5% 90 90 100 100

25% 90 90 90 100

50% 90 80 80 90

100% 50 40 40 50

You have to convert these to ?proportions

Pimephales promelas Dry Weight (mg)

Replicates

Percent Effluent Rep 1 Rep 2 Rep 3 Rep 4

Control .620 .637 .567 .642

6.25% .598 .642 .588 .632

12.5% .601 .598 .599 .602

25% .596 .572 .534 .535

50% .504 .510 .498 .472

100% .342 .298 .355 .301

Zebroid, Zebrass, Zonkey or Ze-donk.

We are not in Kansas anymore Toto.

Cultivated Land – Milo and Corn

Metal Plating

Landfill

Warehouse District

City Limits 90,000

Pig Farms

Municipal WRP

Seepage

Impervious surface

Impervious surface

Roads, roofs, parking lots, storm drains, construction sites

Any stream with greater than 6% impervious surface in its watershed will be degraded

A I R

BASE

The designated use ofthis segment is high aquatic life

Define the problem:

Based on dissolved oxygen values a segment of a stream has been determined not to be in compliance for one of its designated uses, high quality aquatic life.

Since the designated use is not being met the segment has been placed on the State’s 303(d) list (303(d) lists should be updated every 2 yrs).

The 303(d) list has been prioritized and submitted to EPA. The priority ranking M (L low, M medium, H high) does not dictate that a TMDL is required but given the location and political will of the area to “fix” the problem it is likely if it is not delisted that TMDL will have to be performed during the next round of listings. (These waters are to be identified and priority ranked according to the provisions established in EPA’s Water Quality Management and Planning Regulation at 40 CFR 103.7(b))

Delisting of Water Bodies as per Texas Water Quality Standards

Starting with the previous year’s list, the first task in the annual update of the 303(d) list is to determine if any water bodies can be delisted for one or more of the following reasons:

more recent data or information refute the original listing;

water quality has improved to meet the standards;

water quality standards have changed so that the original assessment no longer represents a violation of the standard;

assessment procedures (for example, screening criteria) have changed so that a reassessment does not show an exceedance of the criteria;

a TMDL has been approved by the EPA

After examining the delisting requirements it has been determined that the segment can not be delisted. Therefore, a TMDL will be proposed and if accepted instituted.

A TMDL or Total Maximum Daily Load is a calculation of the maximum amount of a pollutant from all contributing point and non-point sources that a waterbody can receive and still meet water quality standards, and an allocation of that amount to the pollutant sources.

The calculation must include a margin of safety (MOS) to ensure that the waterbody can be used for the purposes the State has designated. The calculation must also account for seasonable variation in water quality. Permit limits based on TMDLs are called water quality based limits. The margin of safety should also allow for future point and non-point uses.

Cultivated Land – Milo and Corn

Metal Plating

Landfill

Warehouse District

City Limits 90,000

Pig Farms

Municipal WRP

Seepage

Impervious surface

Impervious surface

Roads, roofs, parking lots, storm drains, construction sites

Any stream with greater than 6% impervious surface in its watershed will be degraded

A I R

BASE

The designated use ofthis segment is high aquatic life

After examining the delisting requirements it has been determined that the segment can not be delisted. Therefore, a TMDL will be proposed and if accepted instituted.

A TMDL or Total Maximum Daily Load is a calculation of the maximum amount of a pollutant from all contributing point and non-point sources that a waterbody can receive and still meet water quality standards, and an allocation of that amount to the pollutant sources.

The calculation must include a margin of safety (MOS) to ensure that the waterbody can be used for the purposes the State has designated. The calculation must also account for seasonable variation in water quality (in our example the problem of low dissolved oxygen is greater in which season and why?) . Permit limits based on TMDLs are called water quality based limits. The margin of safety should also allow for future point and non-point uses.

Policies and Principles

To achieve the water quality goals of the CWA, EPA’s first objective is to ensure that technology based controls (engineering controls) on point sources are established and maintained. Where such controls are insufficient to attain and maintain, water quality based controls are required.

Lack of information about certain types of problems (for example, those associated with nonpoint sources or with certain toxic pollutants) should not be used as a reason to delay implementation of water quality-based controls. What would be the problems associated with setting up a TMDL based on toxicity i.e., we’ve gone to this segment and taken water back to the lab and we’ve found that it is acutely toxic to Ceriodaphnia dubia?

Historically, the water quality based pollution control program has focused on reducing the load of chemical contaminants (e.g. nutrients, biochemical oxygen demand, metals) to water bodies. However, it is becoming increasingly apparent that in some situations water quality standards – particularly designated use and biocriteria – can only be attained if non-chemical factors such as hydrology, channel morphology, and habitat are addressed.

The presence, condition and numbers of types of fish, insects, algae, plants, and other organisms are data that together provide direct, accurate information about the health of specific bodies of water. Studying these factors as a way of evaluating the health of a body of water is called biological assessment.  Biological criteria (biocriteria) on the other hand, are a way of describing the qualities that must be present to support a desired condition in a waterbody, and they serve as the standard against which assessment results are compared [Clear Creek is a reference stream for this area].  The terms biological assessment and biological criteria have sometimes been used interchangeably. This confusion is not surprising considering the interrelationship between the two terms.

Biological Criteria are narrative or numeric expressions that describe the reference biointegrity (structure and function) of aquatic communities inhabiting waters of a given designated aquatic life use. Biocriteria are based on the numbers and kinds of organisms present and are regulatory-based biological measurements.

Biological Integrity - the ability of an aquatic ecosystem to support and maintain a balanced, adaptive community of organisms having a species composition, diversity, and functional organization comparable to that of natural habitats within a region.

Aquatic Community - association of interacting assemblages in a given waterbody, the biotic component of an ecosystem.

Designated Use - classification specified in water quality standards for each waterbody or segment describing the level of protection from perturbation afforded by the regulatory programs. The designated aquatic life uses established by the state or authorized tribes set forth the goals for restoration and/or baseline conditions for maintenance and prevention from future degradation of the aquatic life in specific waterbodies.

Reference Water Bodies – least impacted bodies of water in a region against which the level of degradation of a non-reference stream can be compared.

Because the biological assessments that are required to determine if a segment that has a aquatic life designation are time consuming and expensive the US EPA has developed a series of documents that are referred to as Rapid Bioassessment Protocols or RBPs. One such manual is, Rapid Bioassessment Protocols For Use in Streams and Wadeable Rivers: Periphyton, Benthic Macroinvertebrates, and Fish. Second Edition. This manual and many others can be obtained from www.epa.gov/owow/monitoring

The RBPs contain methods to assess the physical, chemical and biological characteristics of a segment.

http://iaspub.epa.gov/waters/w305b_report_control.get_report?p_state=TX

URL to the next slide in the presentation

Total Assessed Waters of TexasAssessed Waters of Texas by Watershed

Water Quality by Waterbody Type Rivers, Streams, and Creeks

Individual Use Support for Assessed Waters

Water Quality Attainment for Assessed WatersTop State Causes of Impairment

Top State Probable Sources of ImpairmentsLakes, Ponds, and Reservoirs

Individual Use Support for Assessed Waters

Water Quality Attainment for Assessed Waters Top State Causes of Impairments

Top State Probable Sources of Impairments

Red represents links

To implement the TMDL program, the regulation establishes the following definitions for loading capacity, load allocation, waste load allocation, total maximum daily load, water quality limited segments and water quality limited segments still requiring TMDLs. A definition of Margin of Safety is also provided.

TMDL = LC=WLA + LA + MOS

Loading Capacity (LC) – The greatest amount of loading that a water can receive without violating water quality standards.

Wasteload Allocation (WLA) – The portion of a receiving water’s capacity that is allocated to one of its existing or future point sources of pollution. WLA’s constitute a type of water-quality based effluent limitation.

Load Allocation (LA) – The portion of a receiving water’s total loading capacity that is attributed either to one of its existing or future nonpoint sources of pollution or to natural background sources. Load allocations are best estimates of the loading which may range from reasonably accurate estimates to gross allotments, depending on available data and appropriate techniques for predicting the loading. Wherever possible, natural and nonpoint source loads should be distinguished.

Total Maximum Daily Load (TMDL) – The sum of the individual WLAs for point sources and LAs for non-point sources and natural background. If a receiving water has only one point source discharge, the TMDL is the sum of that point source WLA plus the LAs for any non-point sources of pollution and natural background sources, tributaries or adjacent segments. TMDLs can be expressed in terms of either mass per time, toxicity or other appropriate measure that relates to a State’s water quality standard. If other nonpoint source pollution control actions make more stringent load allocations practicable, the WLAs can be made less stringent. Thus, the TMDL process provides for nonpoint source control tradeoffs.

TMDL = LC=WLA + LA + MOS

Water Quality Limited Segments – Those segments that do not or are not expected to meet applicable water quality standards even after the application of technology based effluent limitations required by sections 301(b) and 306 of the Act. Technology based controls include but are not limited to, best practicable control technology currently available (BPT) and secondary treatment.

Margin of Safety (MOS) – A required component of the TMDL that accounts for the uncertainty about the relationship between the pollutant loads and the quality of the receiving waterbody. The MOS is normally incorporated into the conservative assumptions used to develop TMDLs (generally within the calculations or models) and approved by EPA either individually or in State/EPA agreements. If the MOS needs to be larger than that which is allowed through conservative assumptions, additional MOS can be added as a separate component of the TMDL .

TMDL = LC=WLA + LA + MOS

As stated in 40 CFR 131.2 “[water quality] standards serve the dual purpose of establishing the water quality goals for a specific waterbody and serve as the regulatory basis for the establishment of water-quality-based treatment controls and strategies beyond the technology based levels of treatment required by section 301(b) and 306 of the Act.” Standards also contain antidegradation provisions to prevent the degradation of existing water quality.

From State of Texas Water Quality Standards: Antidegradation

Tier 1 – Existing uses and water quality sufficient to protect those existing uses will be maintained. Categories of existing uses are the same as for designated uses, as defined in §307.7 of this title (relating to Site-specific Uses and Criteria).

Tier 2 – No activities subject to regulatory action which would cause degradation of waters which exceed fishable/swimmable quality will be allowed unless it can be shown to the commission’s satisfaction that the lowering of water quality is necessary for important economic or social development. Degradation is defined as a lowering of water quality by more than a de minimis extent (The full expression is de minimis non curat lex. This is a Latin phrase which means "the law does not care about very small matters“), but not the the extent that an existing use is impaired. Water quality sufficient to protect existing uses will be maintained. Fishable/swimmable waters are defined as waters which have quality sufficient to support propagation of indigenous fish, shellfish, and wildlife and recreation in and on the water.

Tier 3 – Outstanding national resources that are defined as high quality waters within or adjacent to national parks and wildlife refuges, state parks, wild and scenic rivers designated by law, and other designated areas of exceptional recreational or ecological significance. The quality of outstanding national resource waters will be maintained and protected.

(4) – Discharges which cause pollution that are authorized by the Texas Water Code, the Federal Clean Water Act, or other applicable laws will not lower water quality to the extent that the Texas Surface Water Quality Standards are not attained.

(5) – Anyone discharging wastewater which would constitute a new source of pollution or an increased source of pollution from any industrial, public or private project or development will be required to provide a level of wastewater treatment consistent with the provisions of the Texas Water Code and the Clean Water Act (33 United States Code, §§1251 et seq.). As necessary, cost effective and reasonable best management practices established through the Texas Water Quality Management Program shall be achieved for non-point sources of pollution.

Assessment of the TMDL - Once control measures have been implemented, the impaired waters should be assessed to determine if water quality standards have been attained or are no longer threatened. The monitoring program used to gather the data should be designed based on the specific pollution problem or sources. For example, past experience has shown that several years of data are necessary from agricultural non-point source watershed projects to detect trends (i.e., improvements) in water quality. As a result, long term monitoring efforts must be consistent over time in order to develop a data base adequate for analysis of control actions.

Sprawl has been identified as one of the causes of increased storm water run off and stream erosion in many watersheds. In a healthy functioning watershed, most precipitation soaks into the ground and is utilized by vegetation, recharges aquifers, and maintains surface water flows. When just 10% of the watershed is developed, streambeds start to degrade due to increased runoff primarily from impervious surfaces. After about 20% of the watershed is developed, most streams have been severely degraded or destroyed.

Forests goods and services… the value of forests is not measured in terms of the goods they provide alone, the services they provide (decreased flooding, water retention, CO2 sequestration, transport of rain to the interior of countries) may be more valuable than the goods. Often referred to as ecological services.

Legacy Pollutants

• Legacy pollutant is a collective term used to describe substances whose use has been banned or severely restricted by the U.S. EPA. Because of their slow rate of decomposition, these substances often remain at elevated levels in the environment for many years after their widespread use has ended. No additional loading of legacy pollutants is allowed or expected due to EPA restrictions. Gradual declines in environmental legacy pollutant concentrations occurs as a result of natural attenuation processes.

Tarrant County water bodies on the State 303d list due to concentrations of legacy pollutants in fish tissue that have resulted in the issuance of a fish consumption ban by TDH requiring a TMDL to be performed. Segment Number Segment Name Fish Tissue

ContaminantsTDH Ban Issued

0829 Clear Fork of the Trinity Below Benbrook Lake, etc.

Chlordane 01/1990

0806 West Fork of the Trinity Below Lake Worth

Chlordane 01/1990

0829A Lake Como (entire lake) Chlordane, DDT, Dieldrin, PCBs

04/1995

0806A Fosdic Lake (entire lake)

Chlordane, DDE, Dieldrin, PCBs

04/1995

0806B Echo Lake (entire lake) PCBs 12/1995

These chemicals are in the edible portions of fin fish.

The Aquatic Life Orders for the Fort Worth Water Bodies were issued on the basis of an unacceptable carcinogenic risk of liver cancer and a noncarcinogenic risk of adverse liver effects due to fish tissue contaminant levels.

The ultimate goal of these TMDLs is the reduction of fish tissue contaminant concentrations to levels that constitute acceptable risk to fish consumers, allowing TDH to remove the bans on fish consumption. The allowable load of contaminant is based on fish tissue concentrations.

Source Analysis• Chlordane was introduced in 1948, and was used

extensively as a broad spectrum insecticide to control soil insects on agricultural crops, as a home lawn and garden insecticide, as a fumigating agent, and for termite control . EPA suspended the use of chlordane on food crops in 1978, and phased out other above ground uses over the following five years. All uses except underground application for termite control were banned in 1983. Manufacture and sales were halted in 1987, and use of existing stores was allowed until April 1998 when sale and use were terminated.

Source Analysis continued.

• DDT was initially used in WWII for control of disease carrying insects, and was used extensively as a broad spectrum insecticide for the control of almost all agricultural and disease-carrying insects. It was used extensively in the 1950s and 1960s for mosquito control in urban areas. DDD is a metabolite of DDT and was itself manufactured as a pesticide for several years. Most uses of DDT, and all uses of DDD, were banned by EPA in December 1972. DDE is the major degradation product of DDT and DDD, and is among the most widely occurring pesticide residues.

Source Analysis - continued

• Dieldrin was used as a pesticide, and is a degradation product of the pesticide aldrin. Although aldrin was used in greater quantity, it is rapidly converted to the more persistent dieldrin in the environment. Both pesticides were used primarily for the control of rootworm and cutworm with some use in the citrus industry and for mosquito larvae and termite control. All food crop uses of both compounds were canceled in May 1975, and only subsurface injection for termite control was allowed after that time. All remaining uses were cancelled in 1987.

Source Analysis – continued.

• PCBs are a group of synthetic organic chemicals containing 209 possible individual compounds, which vary in chemical and physical properties, toxicity, environmental persistence., and degree of bioaccumulation. PCBs were manufactured as mixtures of different congeners, and generally sold under the name Aroclor. PCBs were most widely used as coolants and lubricants in transformers, capacitors, and other electrical equipment. In 1976 TOSCA banned, with limited exception, the manufacture, processing distribution in commerce, and use for PCBs. TSCA also required the EPA to promulgate regulations for proper use, cleanup, and disposal. TSCA and subsequent EPA rules did not require PCB-containing materials to be removed from service and many are still in use (EPA, 1999). A substantial portion of PCBs manufactured before 1977 still remain in service, although these are being phased out as equipment is replaced or decontaminated.

Legacy pollutant contamination in the Trinity River and urban lakes appears to have originated from urban areas, as the watersheds of these water bodies have been highly urbanized for many years. Erosion as a result of extensive urban development over the past 10 to 15 years may have contributed contaminants attached to source soils. Ulery and Brown (1995) evaluated a number of available data sets from the Trinity River Basin, and found a significant correlation between sediment chlordane presence and urban land use. Irwin (1988) found concentrations of total chlordane in mosquitofish to be strongly associated with residential runoff from the area. Kleinsasser and Linam (1989) found elevated chlordane levels in fish collected within the area covered by the TDH consumption ban on the Trinity River, and suggested urban or suburban runoff as the source.

Recent household hazardous wastes (2000) received at the City of Fort Worth Environmental Collection Center have included chlordane (completely banned in 1998), suggesting some recent or possible continued use in the area. Urban residents may have continued using existing stocks of chlordane since it was in use longer than some of the other legacy insecticides. Van Metre and Callender (1997) found the chlordane peak in sediment cores from White Rock Lake in Dallas to have occurred around 1990, reflecting its relatively recent urban use.

Continuing decreases in environmental legacy pollutant levels are expected, although the necessary time frame is subject to debate. Within the context of these TMDLs, legacy pollutants are considered background sources that reflect the site-specific application history and loss rates of the subject area. All continuing sources of pollutant loadings occur from nonpoint source runoff, leaching, or erosion of the various sinks that may exist within the watershed. No authorized point source discharges of these pollutants are allowed by law. Therefore, any contribution from point source discharges would be the result of illegal disposal of these contaminants by customers of the treatment systems. Available evidence suggests that legacy pollutants are generally declining in both the surface sediments and the fish tissue of the affected Fort Worth water bodies. Continuing natural attenuation of these pollutants is expected via degradation and metabolism of the contaminants, burial of contaminated sediment through natural sedimentation in the urban lakes, and scouring and redistribution of sediments in the river.

Natural attenuation is generally a preferred option for the elimination of legacy pollutants. More drastic alternatives, such as sediment removal by dredging, can result in considerable habitat disturbance and destruction, and sediments resuspended during dredging further expose aquatic life to contaminants and the potential for additional uptake, cause abrasive damage to gills and sensory organs of fish and invertebrates, and interfere with fish prey selection. More drastic measures such as dredging or eradication of contaminated fish communities and restocking are generally better justified at heavily contaminate sites impacted by point source discharges and major spills.

The Laguna de Santa Rosa, California TMDL Summary

Temp.

oC

pH Value

6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5 10.0

5 160 51 16 5.1 1.6 0.53 0.18 0.071 0.036

10 110 34 11 3.4 1.1 0.36 0.13 0.054 0.031

15 73 23 7.3 2.3 0.75 0.25 0.093 0.043 0.027

20 50 16 5.1 1.6 0.52 0.18 0.070 0.036 0.025

25 35 11 3.5 1.1 0.37 0.13 0.055 0.031 0.024

30 25 7.9 2.5 0.81 0.27 0.099 0.045 0.028 0.022

Criterion – 0.02 mg/l (as unionized ammonia) for freshwater aquatic life.

Concentrations of total ammonia (NH3 + NH4+) which contains an unionized ammonia

concentration of 0.020 mg/l NH3.

Temp

oC

pH Value

6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5 10.0

5 0.013 0.040 0.12 0.39 1.2 3.8 11 28 56

10 0.019 0.059 0.19 0.59 1.8 5.6 16 37 65

15 0.027 0.087 0.27 0.86 2.7 8.0 21 46 73

20 0.040 0.13 0.40 1.2 3.8 11 28 56 80

25 0.057 0.18 0.57 1.8 5.4 15 36 64 85

30 0.080 0.25 0.80 2.5 7.5 20 45 72 89

Percent un-ionized ammonia in aqueous ammonia solutions

Things we need to understand….

Algal Growth Potential Assay – two major nutrients play an important role in algal growth. These are nitrogen and phosphorus. If you take a sample of water, add phosphorus to it and put it under the appropriate lighting conditions and the algae in the sample grow that tells you what? If you take a sample of water, add phosphorus to it and put it under the appropriate lighting conditions and the algae don’t grow that tells you what (Liebig’s Law of the Minimum). If you do the same experiment but instead of adding phosphorus, nitrogen is added and what you find is that the addition of nitrogen causes the algae to grow but the addition of phosphorus does not, what does that tell you?

When algae photosynthesize the products are _____________ and _____________. When algae respire the products are ______________ and _______________. When the rate of respiration exceeds the rate of exchange of gaseous oxygen in the atmosphere with the water what happens? So if low D.O. is a problem one way to fix it is to increase the turbulence of the water so that there is a greater exchange of atmospheric oxygen and the water, or to control the algal growth by limiting that factor that is responsible for increased growth. In the case described above the nutrient to limit is?

Algal growth and subsequent death also contributes to the reduction of oxygen in the water as a result of?

If this system goes anaerobic there is an additional problem of ? The incomplete breakdown of organic matter results in the production of compounds that are in many cases __________________ , thereby creating a significant secondary problem.

7 mg/l of oxygen as a standard is very high. This suggests that the Laguna de Santa Rosa, Ca. is home to what kinds of fish species?

What happens if a body of water is placed on the 303(d) list because of “toxicity”? What kinds of problems does that present in terms of setting up a TMDL?

The problems with toxicity as a parameter for listing on the 303(d) list is the same as toxicity in an effluent (if the toxicity is associated with the water column and not the sediment). WET tells us whether or not the effluent is toxic or not, just as ambient toxicity tests tell us whether or not the water (or sediment) in an aquatic system is toxic or not. WET tests do not tell us what is causing the toxicity. How do we deal with toxicity in a TMDL or in an effluent.

Most of the time we need to identify what is causing the toxicity in order to be able to control it, either through a TMDL or an effluent control strategy. We do this through what is called a Toxicity Identification Evaluation. Which may or may not be part of a TRE.

A TRE is a plan that is submitted to the regulatory agency issuing the permit to a discharger (EPA, its designee, or an Indian Tribe). The plan is submitted to the permitting agency after an effluent has been determined to be toxic, i.e. the discharger has failed its NPDES WET limits. The steps leading up to the submission of a TRE varies to some degree from permitting agency (state) to permitting agency (state). It could be that a discharger fails its NPDES permit for toxicity, reports that to the permitting agency and the permitting agency increases the frequency of WET testing. If subsequent tests show that the toxicity is gone then nothing else has to be done. If the subsequent tests continue to show toxicity then the regulated facility must submit a TRE. The plan (TRE) outlines the series of steps that the facility is going to take to eliminate the toxicity from the effluent. That plan may or may not contain, but often does, a Toxicity Identification Evaluation (TIE).

The US EPA has issued several guidance documents on TREs and TIEs. We will spend most of our time looking at the Phase I TIE. There is a book that that was published in 2005 that updates some of the information on TREs and TIEs since the last of EPAs guidance documents. I happen to be one of several author/editors of this book. It is not bed time reading, but does contain some interesting detective stories about the process people have gone through to identify toxicants in effluents, ambient waters, and sediments. Generally, there are three phases to a Toxicity Identification Evaluation

Phase I Toxicity Characterization

Phase II Toxicity Identification Analysis

Phase III Toxicity Confirmation Analysis

Phase I Toxicant Characterization Tests

Treatability Approach or Identify Toxicant

Treatability

Approach

Identify Toxicants

Phase II Toxicant Identification Analyses

Phase III Toxicant Confirmation Procedures

Based on Site Specific Considerations

Toxicity Treatability Evaluations

Source Investigation

Effluent Sample

Control Method Selection and Implementation

Post Control Monitoring

TIEs work best on acutely toxic samples. Samples that express toxicity on the seventh day of a Ceriodaphnia dubia test are often very difficult to define. The level of difficulty in determining toxicants in a TIE increases as the toxicity decreases. Freshwater TIEs are generally done with C. dubia because they require less sample to perform than for example P. promelas. However, C. dubia are not more sensitive than P. promelas to all toxicants so care must be taken to ensure that the appropriate identification of the toxicant(s) has been made.

Phase I tests characterize the physical/chemical properties of the effluent toxicant(s) using effluent manipulations and accompanying toxicity tests. Each characterization test in the Phase I series is designed to render a group of toxicants such as oxidants, cationic metals, volatiles, nonpolar organics, or chelatable metals unavailable. Aquatic toxicity tests performed before and after the individual characterization steps, indicate the effectiveness of the treatment to remove or reduce toxicity and provide information on the nature of the toxicant(s). By repeating the toxicity characterization tests using samples of a particular effluent overtime, these screening tests provide information on whether the characteristics of the toxicant(s) causing toxicity remain consistent over time.

Toxic Effluent Sample

Initial Toxicity Test (Day 1)

Oxidant Reduction Test (Day 2)

Baseline Toxicity Test (Day 2)

EDTA Chelation Test (Day 2)

Aeration Tests (Day 2)

C18Solid PhaseExtraction Tests (Day 2)

Acid pHi Base Acid pHi Base

pH Adjustment Tests Day 2

Filtration Tests (Day 2)

Graduated pH Tests (Day 2)

Acid pHi Base pH 6 pH 7 pH 8

Acid Base

What do these tests do?

EDTA Chelation Test – We know from the water chemistry test for hardness that EDTA binds the hardness producing alkaline earth metals calcium and magnesium. We titrate a sample with EDTA in the presence of the indicator calmagite and when all the calcium and magnesium are tied up (chelated) the indicator turns from red to blue. So EDTA binds divalent cations which include such things as zinc, copper, lead, silver, aluminum, nickel, barium, manganese2+, cadmium, cobalt, and strontium.

When a TIE (EDTA test) is performed 10 mls of effluent is added to each cup and EDTA is added in varying concentrations from the LC50 level (EDTA is toxic at higher concentrations) to low levels of EDTA. After the EDTA is added C. dubia neonates (5) are added to each cup. After 24 hours the survival of the C. dubia is determined. If all the neonates in all concentrations are dead that means that the EDTA did not remove the toxicant and therefore metals are not likely the toxicant in this sample. If the middle concentrations remove the toxicity that is a pretty good indication that metals are probably contributing to the toxicity of the effluent.

The same process of treating the toxic sample with one of the TIE characterization steps and then testing for toxicity is common to all the steps.

Oxidation/Reduction – sodium thiosulfate is added to the samples to remove things like chlorine.

Changes in pH (lowering and increasing) makes certain kinds of toxicants more or less available depending on the toxicant.

pH adjustment/C18 is used as a treatment to remove non-polar organics. Chemicals soluble in hexane or chloroform are removed by this step including things like diazinon and other pesticides.

pH adjustment/filtration step removes those chemicals that might be associated with particles in the water that are removed during filtration.

pH adjustment/Aeration test – removes materials that are subject to volatilization like ammonia and cyanide; it also removes or reduces surface active agents like soaps, detergents, resin acids, charged stabilization polymers and coagulation polymers used in some manufacturing processes

The pH (6, 7, and 8) adjustment step removes or helps define toxicity due to things like ammonia. At pH 6 less of the toxic form of ammonia (unionized ammonia NH3) is present. At pH 8 the opposite is true.

It is often true that more than one treatment may have some affect on the toxicity of a sample. For example, it is not unusual to find that in addition to EDTA, some metals are removed when adjusted to high pH and passed through the C18 column, treatment with sodium thiosulfate in the Oxidant/Reduction test will also remove or reduce some metals.

To continue on with our what if scenario we will assume that EDTA removed the toxicity. We know that if EDTA removes the toxicity that more than likely a metal(s) are involved. However, we don’t have any idea at this point which metal(s) is involved. It may be that in an industrial setting finding out that a metal(s) is causing the toxicity may be enough to guide the plant personnel to a particular industrial stream or additive that might be used in a plant. Several times when cooling water from an industrial facility have been determined to be toxic due to metals the operators had a good idea that biocides used to control algae in the cooling towers (many contain copper) might be a likely candidate and changing biocides removed the toxicity and solved the problem. Municipal facilities usually don’t have the same level of knowledge about what is coming into the plant (who knows what some old codger like Vic might be dumping down the drain). Therefore, it is often necessary for these facilities to move to Phase II which is the Toxicity Identification Phase of the TIE.

In the Toxicity Identification Phase things can get pretty complicated and the degree of complexity is in part a function of what has been characterized as the toxicant. We will continue with our determination that a metal(s) is the toxicant as an example of the general process. Experience has shown that if EDTA alone removes the toxicity then copper, lead, cadmium, nickel, and zinc should be measured. When sodium thiosulfate additions reduce or remove the toxicity copper, cadmium and silver should be measured. In part prioritizing what is going to be measured is a function of the method of analysis. If the method of analysis is graphite furnace AA then each metal has to be analyzed separately. If the method of analysis is ICP/MS (inductively coupled plasma with a mass spectrometer) then many metals can be measured simultaneously at toxicologically relevant concentrations and and prioritizing the order of metals analysis is not a necessary.

Once the concentration of the metals in the toxic sample have been determined then one can begin to sort out which metals might be the ones contributing to toxicity. To do this one can calculate the toxic units of the various metals. For example, the acute toxic units TUa can be determined by dividing the concentration of the metal in the toxic sample by the LC50 value for the test organism (C. dubia) in our example. Assume the following

Metal Concentration

ug/l

LC50

ug/l

TUa

copper 100 20 5

silver 25 40 0.625

nickel 200 350 0.571

zinc 400 415 0.96

This table shows that there is sufficient toxicity due to copper alone to cause the results observed in the tests that have been formed. It does not rule out zinc as a possible contributor. Nor does it rule out that there might be an interaction between the metals that we can not account for by this methodology. However, we have enough information to proceed to the Phase III or Confirmation Phase.

The Confirmation Phase of the TIE is probably the most poorly developed of all the phases (in my opinion). What you would like to be able to do in the case of metals is to add a resin that binds up metals that can then be filtered out of the sample. For example, if there was a resin that could be added to the sample that was selective for copper it could be added to the sample, then filter it out and test for toxicity. If the toxicity was removed the copper could be added back into the sample at the concentration that was originally measured and re-test the sample. If the sample was toxic after the copper was added back to the sample we would have pretty good confirmation that copper was indeed the toxicant. The next step would then be to try through the pre-treatment program to figure out how the copper was getting into the system and and then reduce it through treatment by the facility contributing the copper. Some of the new methods discussed in the upcoming book address some of these issues but much research remains to be done.

Once the most likely suspects are determined in Phase II of the TIE, Phase III or the Confirmation Phase kicks in.

Rarely does one step or one test conclusively prove the cause of toxicity in Phase III. Rather, all practical approaches are used to provide the weight of evidence that the cause of toxicity has been identified. The various approaches that are often useful in providing that weight of evidence consist of correlation, observation of symptoms, relative species sensitivity, spiking, mass balance estimates and various adjustments of water quality. We won’t discuss any of these in any detail.

What happens if a designated use for a segment is not being met and the cause is determined to be sediment toxicity?

Again, as with toxicity in the effluent, the sediment toxicity approach is essentially the same except the job is much more difficult and the methods are still in a heightened state of development.

For water TIEs, metals, chlorine, and diazinon have been found to be common toxicants. For sediments, ammonia is frequently identified as the causative toxicant as well as metals.

What happens if a toxicant in the sediment is identified as the causative agent and there is no longer any source in the watershed that could be discharging that toxicant. These are often referred to as legacy toxicants and “we the people” get to pay for the privilege of cleaning this up unless there is historical evidence that a company that is still in business somewhere, but not at this site, then they can be charged with helping to clean this up.