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South Nation River Conservation Authority

Dignard Artificial Wetland

Year 3 of Operation
1997 YEAR-END REPORT

 


EXECUTIVE SUMMARY
ACKNOWLEDGEMENTS
TABLE OF CONTENTS

View /Download Final Report [534 KB pdf]

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EXECUTIVE SUMMARY

This report describes the third year of operation of the Dignard Constructed Wetlands near Embrun in Eastern Ontario. The introduction and the chapter about wetland system design are a synthesis of sections of two previous reports, Proposed Natural System, Dignard Farm - Embrun, Ontario (Weil et al., 1994) and Dignard Artificial Wetland 1995 Year End Report (Weil et al., 1996). The chapter about system performance contains a synthesis of the results obtained during the first two years of operation (Weil et al., 1997). These chapters have been included as background material for readers not familiar with the three previous reports. Readers are referred to these publications for further details on design, construction and results.

At the Dignard dairy operation, stormwater runoff from a solid manure pile and a 0. 75 ha cattle yard is being treated using a constructed wetlands system to avoid polluting a nearby creek. Prior to construction, the runoff from the feedlot was not collected. The runoff from the solid manure pile was stored in an anaerobic lagoon and periodically spread on cropland. The owner of the 100 cow, 165 heifer herd required a system that would treat all the liquid runoff, otherwise separate systems would have been required for handling liquid and solid manure, increasing equipment and labour costs and wasting precious time in the spring.

In 1994, a wetlands system was designed and constructed, following the guidelines advocated by Donald Hammer of Purdue University (Hammer, 1994) with some site specific improvements, to treat the effluent from the manure lagoon and the cattle yard runoff. Wastewater is stored over the winter months and treated during the summer. The wetlands were planted in the spring of 1995 and the system was put into operation that summer. Settleable solids form a nutrient rich sludge on the wetland floor. Aquatic plants (cattails and bulrushes) supply oxygen to the sludge zone through their roots, promoting the breakdown of the pollutants. The plants also act as physical supports for microorganisms which form a "biofilm" surrounding the plant from the water surface to the wetland floor. As water passes through the thick growth of plants, it is exposed to the living biofilm, which filters pollutants and decomposes them. An overland flow system (filter strip) polishes the effluent.

The wetland system has performed beyond expectations over the first three years of operation. Average reductions in concentrations at the outlet of the second wetland cell (compared to levels in the lagoon) in 1996 were: 98.7% (33.3 mg/l), 97.8% (19.7 mg/l) and 95.3% (4.27 mg/l) for BOD5, TKN and TP, respectively. Mass reduction of these pollutants at the same stage of treatment was higher than 98.8% during the same year. Based on the concentrations, overall performance of the system in 1997 is similar to 1996 for BOD5, but somewhat inferior for TKN and TP. Average reductions in concentrations at the outlet of the second wetland cell (compared to levels in the lagoon) were: 97.2% (32.8 mg/l), 93.7% (26.5 mg/l) and 86.4% (9.07 mg/l) for BOD5, TKN and TP, respectively. It should be mentioned that true comparison of the performance can only be achieved with a mass balance. A mass balance would indicate a higher performance, as water flow diminishes along the system. Due to evaporation, the water flow on the filter strip was so small that it could not even be sampled. Considering this small flow and the level of concentration reduction, the overall performance of the constructed wetland was good.

 

ACKNOWLEDGEMENTS

The following partners made the construction of the Dignard Constructed Wetland possible:

Agriculture and Agri-Food Canada (Rural Conservation Clubs)
Alfred College of Agriculture and Food Technology
Michel and Hector Dignard - landowners
McNeely Engineering Consultants, Ltd.
Ontario Cattleman’s Association
Ontario Ministry of Agriculture, Food and Rural Affairs
Ontario Ministry of Environment and Energy
Ontario Soil and Crop Improvement Association
Russell Soil and Crop Improvement Association
South Nation River Conservation Authority

The Dignard Constructed Wetland project was managed by a committee composed of the following members:

Gaston Patenaude, Committee Chair
Michel Dignard, Landowner
William Kollaard, Alfred College, University of Guelph
André Lemay,Ontario Ministry of Agriculture, Food and Rural Affairs
Cam McGowan,South Nation River Conservation Authority
Denis Perrault,Ontario Soil and Crop Improvement Association
Gerald Poupart,Russell Soil and Crop Improvement Association
Paul Sabourin,Ontario Ministry of Agriculture, Food and Rural Affairs
Eric Tousignant, McNeely Engineering
Leslie Vanclief,South Nation River Conservation Authority
Claude Weil,Alfred College, University of Guelph
Mary-Ann Wilson,South Nation River Conservation Authority

The 1997 Year End Report was written with the collaboration of the following people:

Pierre-Alain Blais, Alfred College, University of Guelph
Olivier Fankhauser, Alfred College, University of Guelph
William Kollaard, Alfred College, University of Guelph
Leslie Vanclief,South Nation River Conservation Authority
Claude Weil, Alfred College, University of Guelph

 

TABLE OF CONTENTS

Executive Summary
Acknowledgements
Table of contents
1. INTRODUCTION
2. WETLAND SYSTEM DESIGN
2.1 Free water surface wetlands
2.2 Layout of Dignard wetland system
2.3 Design parameters
   2.3.1. Hydrological considerations
   2.3.2. Surface loading rates
2.4 Summary of dimensions
2.5 Schedule of operation
3. MONITORING
3.1 Surface water monitoring
3.2 Ground water monitoring
3.3 Temperature and water levels
4. SYSTEM PERFORMANCE
4.1 Reduction in pollutant concentrations during the 1996 monitoring season
4.2 Mass balance of pollutants for the second year of operation
   4.2.1 Methodology
   4.2.2 Results
   4.2.3 Discussion
4.3 Results for the 1997 operating season
   4.3.1 BOD5
   4.3.2 Nitrogen
   4.3.3 Phosphorus
   4.3.4 Dilution and concentration effects
5. COST ANALYSIS
6. CONCLUSION
REFERENCES


 

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