Lindsay storm sewer outfall study

Below is the full scientific report commissioned by KLSA, produced by Fleming College Students, and released in April 2010.  An abridged version, with photographs and more charts, is included in KLSA’s 2009 Annual Report.

Preface

The Kawartha Lake Stewards Association requested that a project entitled “City of Kawartha Lakes Storm Sewer Outfall Impacts Study” be conducted by students in the Credit for Product course in the third year Ecosystem Management Technology program at Sir Sandford Fleming College. This study was conducted during the months of September – December 2009 by students Kathleen Wylie, Stephanie Theriault and Mark Gaizauskas, under the supervision of Professor Sara Kelly.

The water samples were taken from eight storm water outfalls in Lindsay, Ontario. The samples were tested for phosphorus and E. coli levels. The results of the tests were used to recommend mitigation strategies to reduce levels of phosphorus and E. coli entering water bodies such as the Scogog River from the storm water outfalls.

Introduction

In urban environments, many different contaminants run off of lawns, streets, and sidewalks during rainfalls. These contaminants then flow into a storm sewer system and usually end up in water bodies, with little to no filtration along the way. The Ministry of the Environment has designated storm water contamination a significant problem for watersheds that include urban areas (MOE, 2003). There are many techniques that can be used to lessen the damage done by contaminants (Weiss et al, 2007). First, the threat must be understood, especially its source. Two of the most significant contaminants are phosphorus and E. coli (Escherichia coli), which have been considered in this study.

E. coli can have many sources, including fertilizers and feces from agriculture, overflow from sanitary sewer systems, failing septic systems, and feces from domestic pets. E. coli is not naturally found in water, and cannot survive long once outside of the intestine of the organism. This means that any E. coli found in water samples is from recent contamination (Canadian Council of Ministers of the Environment, 2009). If water is not treated for E. coli before drinking, humans can become severely ill, with symptoms such as bloody diarrhea, abdominal cramps, and fever. In some cases, it can even lead to kidney failure and death (Canadian Council of Ministers of the Environment, 2009). There is a guideline published by the Federal-Provincial-Territorial Committee on Drinking Water, which specifies that E. coli should not be present in drinking water, and states that, for recreational water E. coli levels, “the geometric mean of at least five samples, taken during a period not to exceed 30 days, should not exceed 2000 E. coli/L. Resampling should be performed when any sample exceeds 4000 E. coli/L.” (Federal-Provincial Working Group on Recreational Water Quality, 2009).

Phosphorus is a limiting nutrient, and occurs naturally in rocks, soil, animal waste, plant material, and the atmosphere. It is also used in fertilizers, which is used in agriculture and home gardens and lawns, found in discharge of industrial and municipal waste, and surface water runoff from residential and urban areas (Canadian Council of Ministers of the Environment, 2009). Human health is not threatened directly by phosphorus, but indirectly by affecting drinking and recreational water sources. It can promote the growth of toxic algal blooms, which affect the potability, taste, odour, and color of the water. Overall, excess phosphorus can contribute to the eutrophication of water bodies (Canadian Council of Ministers of the Environment).

Because Phosphorus has no direct effect on human health, there are no set guidelines for acceptable levels found in drinking water. There also are not any national guidelines for phosphorus for the protection of aquatic life. A framework for the management of phosphorus in freshwater systems is being developed by the CCME Water Quality Task Group to address the issue (Canadian Council of Ministers of the Environment).

The location of the storm water outfall study is in the town of Lindsay (City of the Kawartha Lakes), Ontario, which has a population of 16 930. The bedrock is primarily limestone and alluvial plains. The Scugog River runs south to north through the east end of town. The majority of the storm water outfalls drain into the Scugog River, so the outfalls chosen to sample from are located at different points along the river.

Most of the outfalls are draining storm water from residential locations, and are found at the end of streets. There are also outfalls draining storm water from the downtown streets. The type of storm water system used in Lindsay is a separate system, as opposed to a combined system. This type of system is used to prevent mixing of raw sewage with storm water runoff.

Purpose and Scope

The purpose of this study is to determine the amount of phosphorus and E. coli found in runoff from storm water sewer outfalls in Lindsay, Ontario. This is a preliminary study of storm water in the Lindsay area. The results will then be used to make recommendations regarding additional studies in the area, and treatment of storm water before it can reach large water bodies such as the Scugog River. Samples of storm water runoff were collected from eight locations and tested at the Center for Alternative Wastewater Treatment lab at Sir Sandford Fleming College in Lindsay, Ontario. The final report will be given to the Kawartha Lakes Stewards Association, as well as being submitted to Sara Kelly for marking in the Credit for Product course in first semester Ecosystem Management Technology program at Fleming College.

The scope of the study is limited to storm water outfalls in Lindsay, Ontario. There are also a limited amount of samples to be taken, due to monetary and time constraints. Topics researched for this study include phosphorus, E. coli, and types of storm water systems found in municipal areas as well as treatment practices.

Methods and Materials

The City of Kawartha Lakes provided maps of the storm sewer system. From these maps eight outfall locations within the city were chosen, and samples were taken and tested for phosphorous and E. coli levels. These locations were compared against all of the outfalls in Lindsay and were then picked as representatives of the total outfalls, for their size, flow rate and land use. Please refer to Table 1 for an over view on the outfall characteristics.  Land use varied from low traffic urban sites to high traffic urban sites and from residential to commercial.  Samples were collected within the first hour of a major rainfall event, and the previous rainfall date was recorded. Clean sample bottles were rinsed twice in situ with outfall water; the bottles were filled, capped and shaken, leaving an inch at the top for thermal expansion. To ensure accuracy all samples were sent to the lab at the Center for Alternative Wastewater Treatment at the Frost Campus at Fleming College which is certified to test phosphorus and E. coli by the Canadian Association for Laboratory Accreditation.

Table 1: Outfall Characteristics
 

Outfall # Location Size (inches) Flow Rate Land Use
1 South end of Lindsay, where Lindsay Street crosses the Scugog. This outfall is upstream of the others. Medium(25-36) moderate Agricultural, Cemetery
2 End of Mary Street draining east Small (5-20) moderate Residential
3 Drains east from Russell Street Large (36-48) heavy Residential
4 Grassy area north of Riverview Road Medium (25-36) light Residential, Commercial
5 Old site of the rail station, north east of Kent and Lindsay Streets Large (36-48) heavy Commercial
6 Along the bike path north of Kent Street Small (5-20) heavy Commercial
7 Along the bike path north of Kent Street Large (36-48) very heavy Commercial
8 North end of city near Pottinger Street, draining east into the Scugog, and downstream of the other sites. Medium (25-36) moderate Residential

Results

Table 2 is the data collected from the eight samples and shows the amount of phosphorus and E. coli found in the samples. It also includes relevant information including the date and time the samples were collected.

Table 2: Displays the test results of the samples collected on November 19, 2009.

Sample Time Total Phosphorus as P (mg/L Total Coliform (cfu/100ml) E.coli (cfu/100mL)
Outfall 1  09:30 0.73 103800 1300
Outfall 2  09:40 0.17 79400 1600
Outfall 3  09:45 0.49 548000 87600
Outfall 4  09:50 0.53 236
Outfall 5  09:52 0.53 469600 23600
Outfall 6  09:55 0.26 415200 30400
Outfall 7  10:00 0.40 343200 26000
Outfall 8  10:05 0.29 13700000 2000000

Discussion

In the investigation of Lindsay and the outfalls, it was predicted that the runoff would show average levels of E. coli and phosphorus. Since the testing was conducted in the fall it was hypothesized that lower levels of phosphorus would be found, because fertilizers, which are a large source of phosphorus, are typically used during spring and summer months. Many of the studies show that commonly phosphorus levels are deemed average when they are between 0.006 to 0.561 ppm. For analytical purposes these parameters will use to determine if the runoff is average (Gartner Lee Limited, 2009). This city also contains forested areas and some natural buffers and small wetland areas around the Scugog River, which will help trap contaminants before they reach the water, and also filter runoff.

E. coli is usually a serious problem when there are heavily populated wildlife areas, water fowl or domestic animals. When areas are not permeable it causes concentrations to rise drastically (Canadian Council of Ministers of the Environment, 2009). Paved areas and turf grass are not very efficient at breaking down the wildlife feces, whereas tall grasses and natural buffers are a significantly more efficient (Turfgrrl, 2009).  During conditions of saturation-excess, E. coli are found to be quickly transported across the surface of saturated soils, and do not have much of an opportunity to unite with the soil matrix (Muirhead et al, 2005). Since the City of Kawartha Lakes has a healthy level of riparian plant life and natural buffers around the river, it was predicted that E. coli would be inhibited from flowing freely across the soil surface, and the levels should fall within the average concentrations or E. coli in sewer outfalls. 

According to the Federal-Provincial Working Group on Recreational Water Quality, in water used for recreation, concentrations of E. coli should not exceed 200 E. coli/100mL (Federal-Provincial Working Group on Recreational Water Quality, 2009).  Drinking water should contain zero E. coli after being put through a filtration process. 

The information being used as comparisons for average levels of phosphorus and E. coli are for water bodies, not outfall water, so it is expected that the numbers may be slightly higher and still in a relatively normal range.

The test results denied the hypothesis. Five of the storm water outfalls tested extremely high for E. coli, with outfall number eight having extremely high E. coli levels (2,000,000 cfu/100mL).  It is conjectured that raw sewage may be interspersed with the outfall water.  One study states that E. coli counts in storm water usually range from 103 to 104 E.coli per 100mL, and that higher counts such as 105 units per 100mL could indicate the presence of cross-connections with sanitary sewers (Marsalek and Rochfort, 2007).  Outfall numbers three, five, six, seven, and eight all fall well above the recommended range.

Test results confirmed the hypothesis for phosphorus. The first storm sewers showed slightly high levels of Total Phosphorus. The levels used for comparison were for the overall water body levels so having slightly higher levels in runoff was to be expected. This shows that the Scugog River has an acceptable amount of phosphorus. It is important to maintain or lower these levels, to prevent the lake from becoming eutrophic. If this study was conducted in the spring and summer months, the levels would most likely be higher due to high usage of fertilizers (Barbiero et Al, 2002).

During the research, some complications with the sampling were encountered due to the weather. When interpreting the results, the problem was faced of not having actual runoff averages from other studies. In the data, interferences were encountered because sampling was started 30 minutes into the rainfall and finished one hour into the rainfall. It is recommended that all samples should be collected within the first 30 minutes of the rainfall, to collect the highest and most accurate concentrations in runoff. Further research needs to be done to back up the test results. In the future areas should be tested at the same time during the rainfall; this would help remove bias from individual samples.  

 Recommendations

  The general consensus from all the literature read is that phosphorus and E. coli tests should be conducted year round for several years, in order to better understand the potential severity of the issue. Therefore it is recommended that the Kawartha Lakes Stewards Association follow-up this preliminary study with a more compete study. Several of the outfalls show high levels of phosphorus or E. coli.  The creation of more natural buffers around outfalls is also recommended. In approximately half of the outfalls studied, there is adequate space to build constructed wetlands before the runoff is introduced into the Scugog River. This is also the most natural way of solving this problem, and will mitigate other pollutants from entering the Scugog River while having the potential to be aesthetically pleasing. This technique appeared most often in the literature and seemed to have a high success rate with a relatively low cost.

From the literature that was reviewed it was concluded that constructed wetlands would be the most appropriate way to reduce the amounts of E. coli and phosphorus. This is also a cost effective way and has been proven effective. However, this will not remove all of the E. coli, but will lower the concentration. It is also a natural approach that requires little follow up work to maintain effectiveness (Weiss et Al, 2007). Bio-retention ponds are very similar and also an effective method of removing phosphorus and E. coli. A study in North Carolina showed that E. coli levels were lowered by 71% because of the use of this technique (Hunt, 2008).

Sand filtration is another possible technique for removing phosphorus and E. coli. On the other half of the storm sewers that do not have the room to construct wetlands, this should be considered. This method requires very little area and is very cost effective (Erickson et Al, 2007).

It is also recommended that the source of E. coli on outfall # 8 be researched further. It is possible that raw sewage was interspersed with the outfall water. The best analysis of this would be that there may be a cross-connection with a sanitary sewer (Marsalek and Rochfort, 2007). There is also a possibility that a sewage pipe has started to leak and is infecting the area that drains into this outfall.

During sampling it was also observed that there is a good possibility of high levels of chemical pollutants and sediment loading during rainfall events. This may also be causing problems for the water body. It would be an asset to have this data as well to get a better analysis of the health of the river and the runoff quality. 

Conclusion

 Understanding the effects of storm water on local water bodies is always important.  In the area this study was conducted in, the effects are especially important because the town of Lindsay draws its drinking water from the Scugog River, and it is also used for recreational purposes.

In the urban areas of Ontario, beaches are seasonally shut down because of high levels of E. coli, which may cause health problems for people that use the water for recreational activities. This also applies to the Kawartha Lakes.  If there are high levels of E. coli and phosphorus this should be publically noted and corrected.

 Excess phosphorus loading causes plankton and algae to grow exponentially. This will eventually cause aquatic organisms to suffocate because of the large amount of oxygen required to decompose algae. This will also make the body of water become less attractive because the taste, color, and odour will change (Canadian Council of Ministers of the Environment, 2009).

The results of testing showed that there are extremely high concentrations of E. coli in five of the runoff samples. They also showed that one outfall had above average levels of phosphorus. This study should be followed with a more thorough and in-depth look at the storm water in Lindsay, as no data previously existed to state whether or not this is a significant and ongoing problem. The outfalls need to be monitored year round, to understand the complete cycle of water and contaminants that move through the storm water system. Only then can the impact be fully diagnosed and only then can a proper solution be put forth.

 References

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Monitoring and Sustaining the Health of the Kawartha Lakes

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