Biju Karumanchery, Director of Planning & Urban Design, introduced the item, advising that today’s presentation will provide an overview of City’s existing stormwater management ponds, and the approach the City has taken in regards to unground stormwater management facilities. Mr. Karumanchery advised that the staff recommendation focuses on the permitting an underground stormwater management tank for the two draft approved plans of subdivision in the Future Urban Area of the Robinson Glen Secondary Plan, but noted that other developers have also approached the City in regards to permitting underground tanks on their development sites.
Frank Clarizio, Director of Engineering, provided a presentation entitled “An Overview of Stormwater Management Ponds and Unground Tanks”.
The following deputations were made on the presentation “An Overview of Stormwater Management Ponds and Underground Tanks”:
Greg Dziewiecki, Stormcom Inc. was hopeful that the City of Markham will be open to many different concepts pertaining to storm water management facilities. Mr. Dziewiecki supported storm water facilities versus storm water ponds.
Don Given, Malone Given Parsons, requested that the Development Services Committee support the staff recommendation on underground storm water management facilities. Mr. Givens spoke of the benefits of underground stormwater management facilities, such as it promotes a more efficient use of land and it beautifies the community. Mr. Given displayed an aerial sketch of the Robinson Glen Demonstration Plan showing where the underground stormwater facility would be located, and how it will create more parkland for future residents of this community. Mr. Given showed other examples of underground stormwater facilities, including a stormwater storage tank located under a sports field at Bill Crothers Secondary School.
Katya Servalle, Decast Ltd., displayed different types of underground stormwater management systems to the Committee, explaining how they are designed and maintained. Ms. Servalle noted that based on their models their underground stormwater management facilities should not require servicing for 100 years.
Dave Hardy, Hardy Stevenson and Associates Ltd., suggesting that having underground stormwater management facilities increases property values. Mr. Hardy shared the results of a survey his organization took on stormwater management ponds, which found that 97% of the people surveyed would prefer a public park on top of a tanked stormwater management pond rather than a stormwater management pond. Mr. Hardy advised that he did not think the wording of the survey was biased.
The Committee discussed the following relative to the presentation “An Overview of Stormwater Management Ponds and Underground Tanks”:
- Suggested that it is logical to bury stormwater management ponds when land is very expensive;
- Discussed the various types of stormwater management facilities and the types of considerations that are made when selecting a stromwater management facility, such as the load it will need to hold, and the building standards it will have to meet.
- Noted that the City does not typically get complaints regarding the odour of its stormwater management ponds;
- Questioned how the City will protect future residents against substantial future costs related to maintaining parks built on top of stormwater management tanks.
Staff and the deputant provided the following responses to inquiries from the Committee:
Mr. Clarizio clarified that only City managed stormwater management ponds were included in the presentation, and that the developer is responsible for developing the stormwater management pond or facility. Mr. Clarizio noted that some type of an agreement would need to be made with the developer in regards to the maintenance of any underground stormwater facility. Mr. Clarizio advised that the City will need to develop policies to determine when it is suitable to have an unground stormwater management tank, and that requests for underground tanks would need to be reviewed on a case by case basis.
Ms. Servalle advised that water from a stormwater management tank can be used for irrigation or other purposes, and that a bobcat cleaner can be put inside the tank to clean it. Ms. Servalle clarified that water in stormwater management tanks does not typically have an odour, as the water is generally quite clean as it is not exposed to the outer environment and does not stay stagnant for long periods of time. Ms. Servalle suggested that it is unlikely that the entire case of the stormwater tank will ever have to be replaced, rather damage can be addressed locally, similar as to how a bridge would be repaired.