Environmental Management Plan

One of the key ways that York Region can ensure that the project is not negatively affecting the natural environment is to monitor for any changes. There are two "Governing Environmental Principles" for this project:
1. Proactive management of stress to the natural environment, and
2. A mitigation plan that incorporates comprehensive monitoring and adaptive management.

The Environmental Management Plan (EMP) that has been developed for this project is designed to protect the natural functions of the ecosystem, including:

Fish and fish habitat
Wetlands
Streams
Woodlots

EMP Binder Downloads:

16th Avenue Trunk Sewer Phase II Environmental Management Plan Executive Summary - Document 1 of 5 - May 2004 EMP Binder 1
16th Avenue Trunk Sewer Phase II Environmental Management Plan Report - Project Understanding - Sections 1 to 7 - Document 2 of 5 - May 2004 EMP Binder 2
16th Avenue Trunk Sewer Phase II Environmental Management Plan Report - Fish Habitat - Section 8 - Document 3 of 5 - May 2004 EMP Binder 3
16th Avenue Trunk Sewer Phase II Environmental Management Plan - Wetlands and ESA - Section 9 - Document 4 of 5 - May 2004 EMP Binder 4
16th Avenue Trunk Sewer Phase II Environmental Management Plan Report - Environmental Management Plan - Section 10 - Document 5 of 5 - May 2004 EMP Binder 5

Please click on your choice of the above areas to find more detailed information on the monitoring and protection zone of each natural functions as it is described in the Environmental Management Plan (EMP).

Figure 4.1 below shows all of the monitoring sites and the Zone of Influence (ZOI) for the 16th Avenue project.

Fish and Fish Habitat:

"During construction of the sewer along 16th Avenue, it is necessary to depressurize and dewater the confined aquifer in order to create safe working conditions as discussed in Section 3 of this report [the EMP]. Once the desired water levels have been achieved the pumps must remain active to maintain the pressure relief until the majority of the sewer construction is complete. As a consequence of confined aquifer dewatering, impacts on the natural environment can manifest in two forms:

Impacts due to reduced groundwater upwelling; and
Impacts due to dispersal of dewatering discharge.

The reduction of groundwater contribution may reduce the baseflow in creeks thereby impacting potential spawning, rearing and overwintering areas for native fish species. The dispersion of large volumes of dewatering discharge to the tributaries south of 16th Avenue may alter the geomorphology of the creeks by eroding the creek banks or create higher velocities that prevent upstream fish migration. The difference between groundwater and surface water physical and chemical characteristics may also negatively impact aquatic or benthic life functions and cause fish species migration. Robinson, Bruce, Berczy, Burndenet and Exhibition creeks are proposed to receive dewatering discharge under the operational plan for Phase II. The bulk of the dewatering discharges to the streams will be released at 16th Avenue. The potential effects in the streams associated with dewatering discharges under Phase II could include:

Potential erosion of the creek banks and substrates on occasions when the critical discharge threshold is exceeded;
Increase in frequency of inundation of the streambanks and riparian vegetation during natural freshets;
Seasonal alteration of natural hydrographs as a result of the scheduled dewatering discharges;
Increases in available fish habitat through increases in channel wetted perimeter and alcove and off-channel habitat area;
Increased opportunity for fish to migrate upstream because of increased flows and behavioural response to higher flows;
Increased coldwater habitat area causing migration and dispersion of coldwater species (i.e., salmonids) into tributaries where the coldwater species would normally have been limited by lower flows and higher temperatures;
Disruption and possibly curtailment of metabolism, respiration, feeding, reproduction, larval development, and migratory behaviour in some native fish;
Displacement downstream, away from the cold water influx, by some intolerant warmwater fish species; and
Thermal shock if discharges occurred during high summer temperatures or a period of acclimation did not occur.

In the following sections, the zones of impact are delineated, fish species composition and stream habitats are described, and the potential impacts, proposed mitigation and monitoring for the Phase II project within each stream are outlined. Further information and details on these topics are provided in Appendix D [of the EMP].

Figure 10.2 from the EMP shown below shows the response plan for Fisheries if monitoring indicates that a "trigger" for mitigating action has been set off."

[Source: Binder 3 of the EMP, pages 8-1 and 8-2 and Binder 5, Figure 10.2]

Wetlands:

"In establishing any monitoring program, the rationale of the monitoring must be clear, cause and effect relationships must be established, and a decision must be made on what is to be done should impacts be observed. Before describing the individual candidate wetlands being considered for monitoring, it is important to establish these principles as they relate to all such wetlands. The following considerations are of particular relevance to this exercise.

The ultimate objective of the monitoring is to determine whether the long-term functions and attributes of wetlands within the shallow zone of impact are being negatively impacted by dewatering.
While, in a best case scenario, it may be possible to intervene should there be evidence of changes within a wetland, there may be several technical obstacles to doing this. In this regard, the replacement of baseflow within a creek, which will have positive influences several kilometres downstream, is much simpler than restoring losses of groundwater contributions to a wetland in which such contributions may be much more widespread. Should impacts be observed, a variety of options will need to be assessed, to determine whether wetland functions and attributes can be maintained; however, the monitoring program must have secondary objectives of:

assessing the permanent nature of any such changes, and whether the wetland's functions and attributes are restored following the termination of dewatering activity;
assessing functions and attributes which may be lost, but which can later be restored through active intervention; and
determining the magnitude and significance of potential short-term and long-term losses of wetland functions, in order that appropriate compensatory measures can be considered.

Initial monitoring work will be necessary to fine-tune the monitoring program, and longer-term monitoring should remain adaptive to the results. For example, in certain wetlands, it may be decided that additional monitoring is warranted, whereas at others it may be appropriate to pare the efforts down, or discontinue the monitoring altogether.
As intervention may be possible, it is important to select parameters which are clearly related to dewatering and which provide, to every extent possible, an "early warning" system, allowing for intervention before the flora and fauna of the wetland are negatively impacted.
At the same time, it must be recognized that a change in, for example, soil moisture levels, does not necessarily translate into a negative impact on vegetation or wildlife resources (which, given the nature of wetlands, must be at least somewhat resilient to changing environmental conditions). It is therefore important to monitor parameters which more directly relate to negative impacts (i.e., components of the biological community), and an adjunct to the "early warning" measurements.
The specific monitoring locations within these wetlands must be those most sensitive to changes in groundwater discharge, thereby serving as a sentry location for the wetland as a whole.
By choosing a good cross-section of wetlands through the area of potential impact, which includes those areas considered most sensitive to change, it is not necessary to monitor all wetlands. The selected monitoring locations can serve as sentry locations for similar wetland areas within the region.
When this approach is taken, it is necessary that the monitoring program allow for additional wetlands to be assessed when impacts are detected on one of the sentry wetlands.
Given the nature of wetlands, establishing cause and effect relationships is inherently difficult. Parallel monitoring of control sites is important to best ensure success.
Due to the complexity of wetlands, impacts may be subtle, and only distinguishable over a period of years. It is important that a multi-disciplinary approach be taken to analyzing the wetland data, in association with data on groundwater levels, fisheries resources, etc., in assessing whether there are changes. It is also important that the data be openly communicated and discussed with the commenting authorities to gain from their insight."

[Source: Binder 4 of the EMP, pages 9-4, 9-5 and Figure 9.1 (ES-12)]
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Streams:

"To delineate the zone of impact associated with the dewatering operation a 3-D groundwater flow model developed by the York-Peel Durham-Toronto (YPDT) Study group was used. This model was developed by the Regional Municipalities and Conservation Authorities within the GTA and the Oak Ridges Moraine with support from the Province and provides the most up-to-date understanding of the geology and hydrogeology of the study area. Details of the model are provided in Section 5 [of the EMP]. As a consensus with TRCA, it was agreed that the regional model developed as part of the YPDT study was to be used to assess drawdown of the shallow water table aquifer and the area within 0.5 m drawdown in the shallow aquifer will be considered as the Zone of Impact (ZOI). The 0.5 m boundary was chosen as it represents the limits of certainty associated with model assumptions as well as field measurements, as the shallow water table varies significantly with seasons. This 0.5 m Zone of Impact (ZOI) as defined in Section 5 [of the EMP] delineates the area with the highest likelihood of potential impact to the stream baseflow as a consequence of drawdown of the shallow aquifer. Also, impacts to streams, fish and fish habitat that result from the release of dewatering discharges to the streams will be most apparent within the ZOI downstream of 16th Avenue. The following creeks or sections of the creeks were identified within the ZOI:

Little Rouge Creek
Berczy Creek
Exhibition Creek
Apple Creek
Robinson Creek
Rouge River mainstem
Burndenet Creek
Beaver Creek
Bruce Creek

All of these streams are managed as cool to coldwater fish communities, even though warmwater species are present. In general, coldwater fish communities are dependent on permanent groundwater discharge for spawning, incubation and thermal refugia, while coolwater communities are less directly dependent on groundwater discharge but require the temperature moderating effect to maintain an optimal thermal regime. Baseline fish surveys were conducted on Highland, German Mills, Duncan Woods, and Morningside creeks. All of these streams are located outside of the ZOI and buffer zone and no significant impact from the Phase II project is anticipated. However, monitoring to assess expansion of the ZOI will be undertaken in Highland Creek and, if needed, mitigation will be adaptively managed according to the process described in Section 10 [of the EMP]."

[Source: Binder 3 of the EMP, pages 17 and 18]

As was previously mentioned, a necessary companion to dewatering is the dispersion of the water once removed from the ground. The map below shows the sites where water will be discharged into streams.

The following is a list of the stream monitoring sites in place as of January 2005:

42 sites measuring temperature, DO, Discharge and Piezometer
31 sites monitoring fish
21 sites monitoring Benthos
12 sites monitoring water chemistry

Woodlots:

"Construction of the 16th Avenue Trunk Sewer Phase II will require dewatering of a major aquifer in the tunnel zone to create safe working conditions for the workers. However, dewatering has the potential to create adverse impacts to other groundwater users as well as the natural environment. The main issues concerning the natural environment are associated with the loss of groundwater contribution to streams, wetlands and ESAs within the zone of dewatering impact and the discharge of excess volume of water from the dewatering operations and its potential to change the natural regime of the receiving water courses. Also of interest are the possible impacts that aquifer drawdown could have on the health of forest stands within the area impacted by the groundwater removal. The relationship between tree growth and water availability has been the subject of considerable study. Of particular interest are the physiological responses of trees to water deficit. However the potential impacts of short-term mechanical groundwater removal on tree growth have received little attention." (p. 139 Binder 4 of the EMP)

"Of particular concern are the potential impacts of the groundwater drawdown on woodlots in areas where the Newmarket Till is less than 30 metres thick and within 2 kilometres of 16th Avenue. This includes the 0.5 km primary Zone of Impact and portions of the 2 km buffer zone. Woodlots on these sites would be more likely to show symptoms of drought than woodlots farther away from 16th Avenue or where the till layer is deeper. A total of 84 separate woodland patches exist within this zone of interest (Figure 1), and amount to about 237 hectares." (p. 145 Binder 4 of the EMP)

"Trees display a variety of responses to drought, most of which are quite subtle and manifest over several years. A long-term monitoring program is necessary to identify any effects that groundwater removal might have on forest health. Monitoring will involve periodic measures of tree growth and soil moisture in woodlots situated inside and outside of the area impacted by the groundwater removal. The monitoring will last a minimum of 5 years and may be extended based on results of the study. Stress in trees manifests in a variety of forms, such as reduced growth, and under severe conditions wilting, leaf shedding and crown dieback. Annual forest growth, referred to as current annual increment (CAI), is often used as a measure of abiotic stress such as prolonged drought (Eamus 2001). Forest growth can be monitored through permanent sample plots. The techniques for establishing sample plots in forests are well defined (Hayden 2003). Permanent sample plots will be established in woodlots along a gradient of soil moisture conditions. Eight plots will be established consisting of 4 plots within the study area, and 4 control plots outside of the area impacted by the groundwater removal. In concert with monitoring of forest growth, measures of soil moisture will be taken at each growth plot using moisture probes located at various depths in the soil. When compared to the control woodlots, these measures will help to determine if soil moisture in the rooting zone of trees is impacted by the groundwater removal and possible relationships with tree growth. The null hypothesis of this study is that groundwater removal does not affect forest growth or soil moisture quantities.

A preliminary analysis of the woodlots in the zone of interest found riparian woodlots where soil moisture is generally readily available and upland woodlots which are typically drier. The effect of groundwater removal may be different between these forest types. As a result, two monitoring plots will be established in each of the upland and bottomland forest types. The proposed location of these plots is illustrated on Figure 2 [of Appendix A in Binder 4 of the EMP]. The figure also identifies woodlots of similar forest types located outside of the area impacted by groundwater removal and that are suitable as control study sites (Table 3). Control plots were located within 10 km of the plots in the zone of interest to minimize potential differences in soil moisture that may result from dissimilar patterns in precipitation. The study sites in the zone of interest were categorized by ELC (Lee et al. 1998) to facilitate selection of control sites of similar forest type. One of each upland and bottomland monitoring plots were located within 0.5 km of 16TH Avenue where the effect of dewatering would likely have the greatest effect on soil moisture." (p. 147 Binder 4 of the EMP)

[Source: Binder 4 of the EMP, pages marked in text]
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