Green Roofs - Living Architecture Monitor - Spring 2018 - 21

CASE STUDY

EPA'S DENVER MODULAR
GREEN ROOF MANAGES
STORMWATER AND MAKES
SPACE FOR PARKING RENTALS
BY STEVEN W. PECK, GRP, HONORARY ASLA

After a green roof design and installation training in Denver in 2017, my
students and I had a special treat - we visited the 10 year old modular green
roof system that lies on the top of the Environmental Protection Agency's
(EPA) Region 8 headquarters.

I

t's the first time I've seen one of the early modular systems, in this case a
Green Grid system, after many years of wear and tear. It was holding up
very nicely. The 19,840 square foot green roof is accessible to building
occupants, features four inches of proprietary growing medium, and six
species of drought tolerant sedum. It's been the subject of plant research
by Jennifer Bousselot of Colorado State University who focused on how
solar panels on the roof impacted plant survival. There is a weather station
that collects rainfall, temperature and other data, as well as a supplemental
irrigation system that provides water during periods of drought. The plant
coverage rises and falls depending on the season, and it was November when
we arrived.
Back in 1969, Denver State Legislators created a quasi-governmental
organization called the Urban Drainage and Flood Control District following some significant flooding events. This new body established water
management goals regarding drainage and flood control over a 1,608 square
mile area, which includes Denver and more than 2.8 million people. The
stormwater retention goal is to retain the 85-percentile storm event, which
in Denver averages out to a 0.6 of an inch precipitation event or less. Cities
determine how the stormwater goals are to be met. In urban areas, buildings

LIVINGARCHITECTUREMONITOR.COM

with more than one half an acre footprint,
such as the EPA headquarters, are required
to manage the 85th percentile storm event
onsite. Typically, civil engineers have met
this requirement by building large retention
vaults for projects in urban areas, which take
up considerable space in the basements of
the buildings. The retention of stormwater
onsite does not contradict Denver's Water Law
requirements for infiltration, as long as stormwater management technologies are allowed to
drain within 72 hours of a rain event.
Research conducted on the EPA building's
green roof demonstrated clearly that the
modular system had no trouble in managing
this much water. Our tour guide, Greg Davis,
of USEPA Region 8 told us, "The green roof
works really well and consistently to meet the
water quality capture requirements. It is also
LIVING ARCHITECTURE MONITOR / SPRING 2018 / 21


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Table of Contents for the Digital Edition of Green Roofs - Living Architecture Monitor - Spring 2018

Table of Contents
Green Roofs - Living Architecture Monitor - Spring 2018 - I
Green Roofs - Living Architecture Monitor - Spring 2018 - Cover1
Green Roofs - Living Architecture Monitor - Spring 2018 - Cover2
Green Roofs - Living Architecture Monitor - Spring 2018 - Table of Contents
Green Roofs - Living Architecture Monitor - Spring 2018 - A1
Green Roofs - Living Architecture Monitor - Spring 2018 - 1
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Green Roofs - Living Architecture Monitor - Spring 2018 - Cover3
Green Roofs - Living Architecture Monitor - Spring 2018 - Cover4
Green Roofs - Living Architecture Monitor - Spring 2018 - M1
Green Roofs - Living Architecture Monitor - Spring 2018 - AD1
Green Roofs - Living Architecture Monitor - Spring 2018 - AD2
Green Roofs - Living Architecture Monitor - Spring 2018 - AD3
Green Roofs - Living Architecture Monitor - Spring 2018 - AD4
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