Below you will find the Town…

Below you will find the Town of New Tecumseth and the Town's consultant, WSP’s peer review comments for the Ministry’s consideration in review of the Tottenham Airfield Corporation (TAC) ECA (Industrial Sewage) application, Ministry Reference No. 0402-B6XSCA. The comments remain outstanding in reference to the review of the following reports believed to form part of the ECA application submission.

• Tottenham Airfield Erosion and Sediment Control Plan (site wide, rev. June 2018)
• Engineering Report on Erosion and Sediment Controls at Northwestern Perimeter of Tottenham Airfield (rev. June 2018)
• Tottenham Airfield Concept Drainage and Stormwater Management Plan (rev. June 2018)
• Aforementioned reports review reference materials based on grading plans (rev.’s May & July 2018)

Town General Comments:

• Presently, it appears unlikely that the proposed grading and elevation targets denoted in the reports may be achieved by TAC. The Site has been under Town Notice to suspend fill importation as of August 2018 and still in effect. Further, the fill permit expires on May 1st, 2019 that will conclude the ability to import additional fill to the site. To date, a permit extension request has not been formally made and approval for extension is uncertain, a decision to be made by Town Council.
• Grading, SWM and some general airfield facilities details identified in the aforementioned reports and plans are consistent with grading plans (rev.’s May & July 2018) and the Development Plan forming part of the Site Plan Agreement. However, when cross referenced with the revised grading plans (rev. December 2018), there appears to be various changes to overall airfield improvement details including grading and SWM. These proposed changes will need to be addressed to align with current soil volumes on site and the status of the fill permit. The Town respectfully refers to the MECP to evaluate any inconsistencies during their ECA review.
• Consistent with the aforementioned northwestern perimeter ESC engineering report, the Town notes an engineering report submission regarding the February 2018 breach event along the westerly boundary of the site was a requirement that remains outstanding to date. This outstanding report is considered the standalone report required to document the spill event from the background and cause of the spill, to the corrective actions in accordance with their corrective action plan as accepted by the Town. As a matter of due process, there has been no opportunity to review the standalone engineering report and cross reference with the summarized discussion found in the site wide ESC report.
• The Town’s Fire and Rescue department have not been contacted for consultation on fire suppression requirements, contrary to the statement made in the Fire Suppression section of the SWM report. The report does not clearly identify the fire suppression approaches and the Town continues to recommend that the Town’s Fire and Rescue department be contacted for input.

WSP Comments:

Tottenham Airfield Erosion and Sediment Control Plan:

• Include contour labels In Appendix C, Figures 3 and 4.
• In Appendix C, Figure 4: Several swales appear to extend down steep slopes and have 90 degree turns. Please provide more detail on velocity controls to prevent scour and erosion of these swales.
• No cross sections or details of the existing or proposed works are provided in this report. The reader is referred to the Northwest ESC report to find details and calculations for ESC measures within the northwest perimeter of the site.  The full-site ESC report should be a self-contained report that does not refer to other reports for design calculations.
• No cross sections or details of the existing or proposed works are provided in this report. The reader is referred to the Northwest ESC report to find details and calculations for ESC measures within the northwest perimeter of the site.  The full-site ESC report should be a self-contained report that does not refer to other reports for design calculations.
• No cross sections or details of the existing or proposed works are provided in this report. The reader is referred to the Northwest ESC report to find details and calculations for ESC measures within the northwest perimeter of the site.  The full-site ESC report should be a self-contained report that does not refer to other reports for design calculations.
• Include within the appendices various final meeting minutes with Town of New Tecumseth and WSP staff.
• Distinguish between proposed and implemented measures on figures in Appendix C.
• Insufficient construction detail is provided for the proposed BMPs. Include standards and notes on drawings showing construction phasing.

Engineering Report on Erosion and Sediment Controls at Northwestern Perimeter of Tottenham Airfield:

• Provide as-built drawings for all constructed works.
• When are the recommended projections for swales to be established? Some of the swales have been constructed, however, not all are hydroseeded as recommended.
• Add stationing to the cross sections and profiles included in Figure 4 in Appendix B.
• The width and location of swale C701 needs clarification. In particular there appears to be a narrowing of the swale at the downstream end just before a 90-degree bend in the swale.  Please provide construction details for this swale including erosion protections, scour protections at all sharp bends (two bends appear to be 90-degrees), and refence to calculations documenting that the swale is adequate to carry the flows it is designed for.
• Swale slopes vary greatly. Confirm flow velocities for swales and specify velocity controls where required.
• Provide details on proposed erosion and scour protection at the confluence of swales C703 and C704.

Tottenham Airfield Concept Drainage and Stormwater Management Plan:

• Figure 4-13 “Pre-Development Model Layout” – provide labeling for junctions and ensure catchment and junction labels are consistent with report body and tables.
• Figure 4-14 Post-Development Model Layout – it is difficult to determine which label belongs to which model object. Please provide closer scale to distinguish labels.
• Drawings are missing from Appendix C which currently includes grading plans. Provide stormwater management plans and details as referenced in the report.
• Peak runoff increases under some design storms and decreases in others for nodes J102 and J203 (Tables 4-19 and 4-20) between existing and proposed conditions; provide the design rationale for this condition. Why are proposed conditions for peak runoff with no stormwater management features substantially different for Node J203 between Table 4-20 and Table 5-5?
• Provide discussion on Quality Control as part of the stormwater management plan.
• Table 4-16 and Table 4-17 present the catchment parameters for pre- and post development conditions to be used in the numerical model. Catchments that are off the airfield property do not have the same catchment parameters in the post development conditions as the pre-development conditions despite no changes being made to these catchments.  Revise the tables and ensure the model reflects the changes.
• Our review of the PCSWMM existing conditions model results suggests several inconsistencies with reporting. Widths for catchments are not consistent with those reported in Table 4-16.  For example, the width of Catchment 1100 in Table 4-16 is listed as 425m – the model lists it as 1008.99.  Several outfalls have not been assigned the correct elevation in the model.  Review and revise.  Conduct a general review of the model and reporting to ensure consistent and correct information in both.
• A review of the PCSWMM post development conditions model generated the following comments (i) outfall 400 and 500 do not have an elevation properly assigned to them, assign proper elevations, and (ii) what is conduit OL1 and why is it surcharging?
• Additional details on the proposed stormwater facility are required: (i) how long is the extended detention? (ii) is the pond designed to achieve quality control? (iii) What is the catchment area for the pond?
• Drawing 15 in Appendix C - provide additional water level elevations; specifically provide the 100 year and extended detention levels.
• Swale C806 discharges to the stormwater management facility close to the outlet of the facility. What steps are being taken to ensure that there is no short-circuiting of the pond to ensure proper quality controls?
• The Transport Canada document Aviation, Land Use in the Vicinity of Aerodromes (Transport Canada Publication TP1247E, 2013/14) is not referenced within the Stormwater Management Report. TP1247E should be considered within the Tottenham Airfield Stormwater Management Plan; particularly the sections of TP1247E that deal with bird and wildlife hazards as they relate to the presence of the proposed stormwater management pond.