HomeMy WebLinkAbout08/16/2011 Engineering Services for July FloodMount Prospect
n/ Mount Prospect Public Works Department
INTEROFFICE MEMORANDUM
TO: VILLAGE MANAGER MICHAEL E. JANONIS
FROM: DIRECTOR OF PUBLIC WORKS
DATE: AUGUST 12, 2011
SUBJ: ACCEPT PROPOSAL FOR HATLEN HEIGHTS AND NORTH PINE /NORTH
WILLE AREA FLOOD STUDIES.
Background
The severe weather that struck the Village on July 23� 2011 resulted not only in a record - setting
rainfall event; it also appears to have set a record for damage to Mount Prospect homes. To
date, almost 700 homeowners have reported basement or other structural damage to their
homes as a result of flooding associated with this storm. Without question, damage of this
magnitude has not been visited upon the Village since the flood events of 1987 and 1988.
The damage appears to be distributed throughout the Village. Attachment A graphically
displays the flood damage reports received to date. It seems that no areas of the Village were
left untouched by this storm. Homes served by separate sanitary sewers seem to have been
affected as much as homes served by combination sewers.
However, the ways in which homes were flooded do vary. Some homes received back -up via
basement floor drains or bathrooms. Other homes were flooded by failed or overwhelmed sump
pumps. Still others took on water via cracks and defects in basement walls. Most unusual are
the homes that were inundated by surface flooding originating in the streets or backyards.
It is the intention of staff to investigate each complaint as thoroughly as possible utilizing the
following protocols:
• Visit each home to learn how they flooded and clearly identify the flood water
pathway(s). Flooding incidents will be classified and mapped.
• Inspect or review (recent) inspection records (CCTV video, manhole inspection reports,
etc.) of Village -owned sewers and facilities to identify defects that could limit the
performance of existing sewer systems.
• Review past flooding complaints, maintenance work orders, and service requests
generated from impacted area.- • Where applicable, evaluate or update sewer flow monitoring data.
• Where applicable, perform surveys of rim and invert elevations to collect information
necessary to understand surface flooding problems.
• Where applicable, develop computerized models (XP -SWMM) to understand the
hydrology of surface flooding problems.
• Prepare a "cause and effect" document that explains why flooding occurred.
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Accept Proposal for Hatlen Heights and North Pine /North Wille Area Flood Studies
August 12, 2011
Formulate options, including cost estimates, to improve the performance of Village
sewer systems and /or reduce the potential for future flooding.
At this juncture, staff has identified two (2) distinct areas that warrant further examination.
These areas are the Hatlen Heights residential subdivision and the single - family homes situated
in the general vicinity of North Pine Street and North Wille Street. Attachment B depicts these
areas.
The Hatlen Heights area is a single - family residential subdivision originally developed as part of
unincorporated Cook County and later annexed to the Village. It is comprised of 354 homes.
48 of these homes (14 %) reported basement or structure flooding following the July 23� storm.
Some of the damage reports detailed extreme flooding: basements filled with 4 -5 feet of water.
Most homes reported basement flooding via surcharging sanitary sewers. However, the most
dramatic flooding is associated with homes flooded by surface waters that travelled overland.
Sanitary wastes generated in this area are conveyed via 23,491 feet of separate sanitary
sewers ranging in size from 8" to 60" in diameter. The separate sanitary sewer system
discharges to the MWRDGC interceptor system on Lincoln Street. The discharge structure
features a pumping station that can maintain some hydraulic flow even when the MWRDGC
interceptors are in a surcharged condition. The sanitary sewer system in the Hatlen Heights
area also features approximately 3,000 feet of 60" diameter sanitary relief sewer installed in
1993/1994 at a cost of $1.9 million.
Stormwater generated in the area is conveyed to Weller Creek via 18,908 feet of separate storm
sewer ranging in size from 6" to 72" in diameter. The entire Hatlen Heights area is tributary to
the Crumley Detention Basin situated on the east side of Busse Road adjacent to Weller Creek.
The North Pine /North Wille area is comprised of 1,019 houses, 3 multi - family buildings, and 10
commercial buildings. It is one of the oldest areas of the Village with a portion of the area
included in the original incorporation and the remaining portions annexed during the 1920s. 100
of these homes (9.8 %) have reported basement or structure flooding following the July 23r
storm. Most homes reported basement flooding via surcharged combination sewers. However,
some homes also reported flooding associated with waters that travelled overland.
Sanitary and stormwater flows generated in this area are conveyed via 48,088 feet of combined
sewer mains ranging in size from 6" to 66" in diameter. All flows are discharged to the
MWRDGC interceptor system beneath Rand Road near Isabella Street. The MWRDGC
interceptor system near this discharge point features a drop shaft connection to the Tunnel And
Reservoir Plan (TARP or "Deep Tunnel'). A portion of this area (bounded by Route 83, Rand
Road, and Isabella Street) benefited from the $4.05 million Prospect Manor /North Main
combined relief sewer project completed in 1993/1994. This project featured the construction of
a large diameter combination relief sewer that drains to the TARP drop shaft near Isabella and
Rand. However, it appears that the most severe flooding occurred in portions of the North
Pine /North Wille area that derived no benefit from the Prospect Manor /North Main relief sewer
project.
In addition, staff has 'identified a need' to "supplement existing forces in order to investigate the
700 flooding complaints received to date in a timely manner. We anticipate that we can
complete approximately 200 building inspections utilizing in -house forces. We will require
external assistance to inspect the remaining 500 homes.
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Accept Proposal for Hatlen Heights and North Pine /North Wille Area Flood Studies
August 12, 2011
Request for Proposals
Staff requested proposals from two (2) consulting engineering firms to provide specified
professional engineering necessary to effectively and expeditiously investigate and analyze the
flooding problems in the Hatlen Heights and North Pine /North Wille areas. Specifically, each
firm was asked to evaluate the existing systems and how they performed during the July 23 Id
rain event. They were also asked to review and analyze collected flooding data and sewer
attribute data as well as develop a hydraulic model that depicts surface flooding in specified
areas. In addition, both firms were asked to provide the resources necessary to investigate up
to 500 flooding complaints. Proposal solicitations were purposefully limited to firms known to
staff to have extensive experience with sewer system evaluations and stormwater management
studies as well as a high degree of familiarity with the Village's sewer systems. The results are
as follows:
Discussion
The lowest cost proposal was submitted by Burns & McDonnell of Downers Grove, Illinois.
Burns & McDonnell has successfully performed a variety of civil engineering projects for the
Village including the study that resulted in the basin 14 overhead sewer installation and footing
tile disconnection project. They also developed the Village's computerized water distribution
model. In addition, the project manager, Randy Patchett, has over 20 years of experience
working with the Village as a consultant including early career work as a staff engineer on a
number of sanitary and stormwater improvement projects.
The Burns & McDonnell fee is approximately half the cost of the Baxter & Woodman fee.
Analysis of this discrepancy revealed-that much of the differential can be attributed to a lower
cost for investigating flooding complaints (on -site building inspections). Burns & McDonnell
intends to complete the work utilizing semi - retired technical staff at a flat rate of $45 per
building. Baxter & Woodman proposes to utilize existing full -time staff at a rate of $112 per
building. The methodology proposed by Burns & McDonnell is acceptable to staff.
Recommendation
It is my recommendation to accept the lowest cost proposal to perform specified professional
engineering services related to the investigation and analysis of floo ing in the Hatlen Heights
and North Pine /North Wille areas as submitted by Burns & McDonnell of Downers Grove, Illinois
in an amount not to exceed $44,500.
can P. Dorsey