Bioretention basin for Erwin Methodist Church to address pooling on Westcott Street, Syracuse, NY

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Bioretention basin for Erwin Methodist Church to
address pooling on Westcott Street, Syracuse, NY
Philip M. Crim and Dr. T. Endreny. FEG340
Engineering Hydrology and Hydraulics, 212
Marshall, SUNY College of Environmental Science
and Forestry, Syracuse, NY 13210.
Design Findings The runoff depth was calculated
using the NRCS Curve Number Method.
(P-0.25S)2 VR
P0.8S The result was 3.2cm, which
multiplied over the entire watershed area results
in a runoff volume of 5.2992m3. Infiltration was
calculated using the Green and Ampt Infiltration
Model
??? fC K ( F 1 ) Using a
sandy loam soil type, infiltration was calculated
to be as high as 39.84cm per every 6-hour
increment of the precipitation event. This more
than twice the required 15cm necessary for every
6-hour increment. Underdrain size was calculated
using Haestad Methods Flowmaster. Due to the high
rate of infiltration as a result of the nature of
the parking lot and the soil type, a diameter of
6 was chosen. In terms of plant species, three
shrub and two perennial species were chosen for
the basin. All were selected for urban tolerance,
ability to survive periods of inundation,
relatively compact nature, and ability to
regenerate (sucker). The shrubs are Leitneria
floridana, Cornus stolonifera, and Alnus
glutinosa the perennials are Hordeum jubatum,
Foxtail Barley, and Puccinelia sp., Alkali Grass.
All are native American species. Conclusion This
project meets the design goals being relatively
inexpensive, not requiring any major changes to
the landscape, and incorporating native plant
species into naturalistic runoff reduction and
purification system. It exceeds the predefined
specifications for infiltrating runoff without
overflowing its berms. In addition, it improves
driver safety by eliminating a large pool of
standing water that forms on a traffic-heavy
street. REFERENCES Atlas of Florida Vascular
Plants. University of South Florida, 2007.
http//www.plantatlas.usf.edu Wurbs, Ralph A, and
James, Wesley P. Water Resources Engineering.
Saddle River, NJ Prentice Hall, 2002. Endreny,
Theodore PhD. Class Notes, FEG340, Spring 2007.
SUNY College of Environmental Science and
Forestry.
Design Goals The purpose of this design is to
provide a solution that is low-cost, requires
minimal changes to the existing landscape, melds
with existing drainage systems, and combines
ecology and aesthetics while satisfying design
criteria/constraints. Bioretention area
diagram(EPA Bioretention Area Fact Sheet,
1993) Design Constraints As with any project,
the design for the bioretention basin must
operate within a certain range of prerequisite
specifications. The maximum basin dimensions for
the project are not limited to a 4x4m area, which
is relatively small. It must be capable of
capturing the volume of discharge created by a
24-hour 2-year precipitation event of 6.8cm. Berm
height, and thus ponding depth, must not exceed
15cm and the underdrain must be tied into the
existin stormsewer/groundwater system. Also,
there must be plants and soil layers present as
outlined in the EPA Bioretention Facility Fact
Sheet. Photo of Leitneria floridana showing
off its ornamental foliage Atlas of Florida
Vascular Plants (2007)
Location Characteristics In its current
incarnation, the site is designed in a very
convenient manner for the placement of the basin,
as the gradual slope of the pavement is such that
almost all of the runoff is conveyed directly
towards the proposed location. Additional runoff
from surrounding areas is insignificant. The
parking lot is completely paved, rectangular and
approximately 36x46m wide, with the longest
hydraulic flow length being 58m. Average slope is
0.0139, and the Manning roughness value for
overland flow is 0.01. The total watershed
drainage area is 1656m2, not counting the basin
itself. Run off drains towards the proposed area
for the basin a driveway leading onto Westcott
Street, where the worst of the pooling occurs.
There is a second driveway leading onto Euclid
Ave, but the pavement is graded so that runoff
drains away from it towards the Westcott street
driveway. Design Alternatives Alternatives
for this project included many options. The
conceptually simplest option is to replace the
blacktop with highly absorbent pavement, which
would greatly reduce runoff, especially since the
parking lot is relatively small. This would,
however, be very expensive. Another option is to
put the basin at the current site of the driveway
on Euclid Ave, but this would also require a
great expenditure as the entire parking lot would
need to be regarded/paved. Overall, no
alternatives came close to the selected design in
terms of cost and utility.
Erwin Methodist Church