Bentley University
OP-27: Rainwater Management

The Bentley University campus is fortunate to contain an open channel stormwater collection system that captures and conveys stormwater runoff through campus. The campus is split into two general areas, the north side of campus where a majority of the academic buildings and several dorms exist and the south side of campus where a majority of the athletic fields exist with more dormitories. The north campus sits largely on a hill with shallow overburden before encountering bedrock, there are exposed rock faces and bedrock outcroppings. At the south campus the topography flattens out to a more level plateau where athletic fields and fitness areas exist and there is a shallow depth to groundwater. The open channel stormwater system sets the tone for stormwater management on campus as an existing openwater system that begins off campus to the north and discharges off campus to the south, the stormwater channel system contains its own homeostatic sustainable ecosystem that has adapted to the urban enviroment that exists in Waltham and through campus.. The University addresses the three main components of stormwater runoff mitigation, Peak Rate control, Water Quality improvement and Total Volume control. The type of stormwater mitigation implemented on campus is dependent on the location on campus. At the north campus the shallow depth to bedrock makes it difficult to infiltrate Stormwater runoff and challenging to install infrastructure systems that are deep so the standard approach to Stormwater mitigation is through surface swales and shallow treatment pools that all eventually connect via pipe or swale, to the main drainage channel on campus. Whereas at the south campus the depth to bedrock is deeper and the groundwater is shallower which allows for the construction of open water extended retention basins.

The current strategy, in addition to complying with standard engineering practice and the City of Waltham design requirements; is to implement the appropriate LID techniques depending on the location on campus. For the North Campus, this generally includes open channel stormwater conveyance to the main stormwater channel and for the South Campus it includes open air extended retention basins that have controlled discharges to the channel.

The University does not currently implement rainwater harvesting strategies. The perennial stream running through campus is dependent on receiving stormwater runoff from the campus in order to maintain a steady flow. Stormwater is delivered to the stream either via overflow discharges from the green infrastructure or through replenishment of the groundwater system.

It has not been a policy of the University to implement proprietary stormwater treatment devices.

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Two new patios, installed during the summer of 2015, used permeable pavers. One at Boylston and the other at the Rhodes building.

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The campus currently does not utilize any formal rain gardens for stormwater management.

There exists two main ponds on campus that are part of the stormwater system. One pond is located on Forest Street near the north entrance of campus and one pond is located on the south campus adjacent to Beaver Street near the location of the new hockey rink. Both ponds receive and treat flow from existing campus facilities such as buildings and parking lots. Most stormwater conveyed to the ponds is treated and conveyed via closed and open drainage.

There are several bioswales on campus, these swales are constructed of both vegetation and rip rap where slopes and low points warrant. The swales as they are implemented address the physical challenges of depth to bedrock and steep slopes that exist on the north campus and serve to slow, infiltrate and clean stormwater runoff prior to discharging to the retention ponds or closed drainage systems.

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