On Monday, Crozier & Associates Partner and Senior Water Resources Engineer Nick Mocan presented alongside Dr. Kevin Stevens of Wilfrid Laurier University at the 2019 CWRA National Conference on how targeted vegetation plantings can be used to enhance water quality treatment in stormwater management facilities. Their presentation covered the last 8 months of site visits, vegetation surveys, and water sampling at a stormwater management (SWM) pond near a subdivision in the Credit Valley Conservation Authority watershed. Dr. Stevens, an expert in wetland plant ecology, discussed the science behind how plants can contribute to water quality treatment, the types of vegetation found at the site, and preliminary water quality analysis results. Mocan drew on his expertise in stormwater management to review the impact of climate change on SWM facility inputs, hydrology, and hydraulics. Mocan also highlighted how this multi-disciplinary research can help stormwater facilities cope with the effects of a changing climate. Preliminary results show that vegetation in the subject SWM pond is performing nutrient removal year-round, but that removal rates are diminished during colder periods. However, there appear to be increasing removal efficiencies as vegetation begins to re-establish itself. Vegetation surveys also noted that volunteer species are contributing to increased species richness, but these plants may not all be desirable. The second stage of this project will involve developing targeted planting mixes based on local hydrologic, hydraulic, and environmental conditions. We anticipate these mixes will provide improved water quality treatment in SWM facilities, prevent incursions of invasive plant species, and contribute to the reduction of nutrient loading in urban stormwater that reaches lakes and streams.

1. Existing Stormwater Management Facilities
Source:
15,000
Municipal Stormwater Management Facilities
2/3
Constructed after 1999

2. ENHANCING YEAR-ROUND FUNCTION
in Stormwater Management Facilities
Through Targeted Vegetation Plantings
CWRA CONFERENCE – MAY 27, 2019
Nick Mocan, M.Sc., P.Eng. | Crozier & Associates Consulting Engineers
Dr. Kevin Stevens | Wilfrid Laurier University

3. The ClimateThe Climate
WINTER
Increased average
winter temperature
RAINFALL
increased winter
runoff
CONTAMINANTS
increased transport of
water-soluble
contaminants
INVASIVE increased
northern limits of
invasive species
2070-2100
+3
to +6
2041-2070
+2
to +4
2011-2040
0
to +2
Reference period: 1971-2000. Climate change scenario: B2
In Colombo et al. (2007); MNR Climate Change Research Report, 2011.

4. The Challenges
1
How well are existing
SWM facilities coping
with climate change?
3
How can we minimize
incursion of invasive
species while still
having cost-effective
plantings?
2
Can we optimize year-round
function in SWM facilities?

5. Dr. Kevin Stevens Nick Mocan, M.Sc., P.Eng. Engage Grant
The Team

6. SAMPLING
 Wet Pond
 Vegetation Survey
 Hydraulic Monitoring
 Water Quality Sampling
ANALYSIS
 Removal Efficiencies
 Key Observations
 Recommendations
 Subdivision
 Coldwater Creek
 CVC Watershed
LOCATION
SW
M
The Project

7. Directly uptake
nutrients
Provide a haven
for microbes
The Science
Re-oxygenate soils
(all seasons)
O2
O2
O2
O2

8. The Science
Permanent pool
Active storage level
Emergent
Free-floating
Floating-leaved Submerged
Wet Pond

9. 86%
91%
94%
20
40
60
80
100
% Removal
Suspended Solids
81%
74%
96%
20
40
60
80
100
% Removal
Dissolved Organic
Compounds
Source: Gersberg et al. 1986
The Science
% Removal
Ammonia
94%
29%
78%
20
40
60
80
100
Scirpus Validus
(Bulrush)
Phragmites Communis
(Common Reed)
Typha Latifola
(Cattail)

10. ANALYSES: YSI Professional Plus Multiparameter Meter, Hach SR3900 Spectrophotometer, Gravimetric:
Total Suspended Solids
The Methodology
 Sampling: Fall 2018
 Identified using
Michigan flora
 Survey: Spring 2019
Vegetation
Survey
 Water depth: Water
level data logger
 Rainfall:
Environment Canada
& Credit Valley
Conservation
Hydraulic
Monitoring
 Water samples
collected at inlet
& outlet
 pH, salinity,
conductivity, K,
NH3, NO3-, NO2−,
N2, TP, O4P-3, Cl-,
TSS
Water Quality
Sampling

11. Alismataceae Apiaceae Asteraceae
Alisma subchordatum Daucus carota Erigeron strigosus
Euthamia graminifolia
Eutrochium maculatum
Lactuca sp.
Solidago canadensis
Symphyotrichum ericoides
Symphyotrichum lateriflorum
Symphyotrichum novae-angliae
Cornaceae Cyperaceae Fabaceae
Cornus stolonifera Eleocharis obtusa
Scirpus atrovirens
Shoenoplectus
tabernaemontani
Securigera varia
Trifolium hybridum
Juncaceae Lythraceae Poaceae
Juncus tenuis Lythrum salicaria Echinochloa muricata
Leersia oryzoides
Panicum capillare
Setaria viridis
Phragmites australis
Polygonaceae Rosaceae Salicaceae Typhaceae
Persicaria hydropiper
Polygonum tenue
Rumex crispus
Spirea alba
Salix sp. Typha latifolia
7
Introduced Species
13
Families
28
Species
The Species

12. Precipitation
mm
Sample
Date
The Monitoring
Oct Nov Dec Jan Feb Mar Apr
18 18 18 19 19 19 19
0
10
20
30
Precipitation
(mm)

13. Total Phosphorus Concentration, μg/L P04 3-
0
500
1000
1500
2000
2500
OCT 31NOV 02NOV 26DEC 18JAN 08FEB 04FEB 24MAR 11MAR 27APR 02APR 16APR 18APR 19
μg/L
The Phosphorus
OutflowInflow

14. 0
5
10
15
20
25
OCT
31
NOV
02
NOV
26
DEC
18
JAN
08
FEB
04
FEB
24
MAR
11
MAR
27
APR
02
APR
16
APR
18
APR
19
mg/L
Total Suspended Solids Concentration, mg/L
The TSS
OutflowInflow

15. Cold Tolerant Species
The Enhancements
Sediment Oxygenation

16. The Progress
1
Water is moving
through SWM facilities
throughout the year due
to winter rainfall, melt
events, and winter
runoff.
3
Need to begin
examining how to
prevent incursion of
invasive species by
using selected
plantings to limit
space for them to
colonize areas in and
around SWM facilities.
2
There is a reduction in removal efficiencies during colder periods.
However, there appear to be increasing efficiencies as
vegetation re-establishes.

17. RESEARCH
Climate change
Winter rainfall
Chloride levels
MONITORING
Rainfall gauges
Continuous
chemistry
Multiple seasons
SITES
Wetlands
Varied climates
Aging facilities
PARTNERS
NSERC
Private-sector
Municipal / Conservation
The Future

18. Contact Us
Nick Mocan, M.Sc., P.Eng.
nmocan@cfcrozier.ca
@nickmocan
linkedin.com/in/nickmocan
Dr. Kevin Stevens, PhD
kestevens@wlu.ca
linkedin.com/i/n/kevin-stevens-
3913707b
We acknowledge the support of the Natural Sciences and Engineering
Research Council of Canada (NSERC).