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Niles Stormwater Plan Phase I Recommendations
Stormwater Plan Phase I Recommendations Presentation & Financing Options Presentation
Updated 10/27/2011
On Tuesday, October 25, the Stormwater Commission and the engineering firm of Hey and Associates presented findings and recommendations for Phase I of the Stormwater Master Plan to the Village Board of Trustees. This was followed by a presentation on financing options by Finance Director Scot Neukirch.
Jeff Wickenkamp of Hey and Associates began by showing the Phase I and Phase II analysis areas and the first modeling overview. This was followed by an explanation of historical rainfall depths and the types of rains (by frequency and duration) that most negatively impact the village’s sewer system. Since 1987, there were three 100-year storms (storms with 1% chance of occurring in any year). The 1987 and 2008 storms were similar (a lot of rainfall over a longer period of time), but the 2011 storm had only an inch less of rainfall in only two hours time.
The topography found on the west and east side of the Phase I study area was discussed.
On the west side, stormwater flows from east to west toward Park Ridge and unincorporated Cook County. This main issue with this flooding is due to downstream flow. No matter how big the pipes are to carry away stormwater toward the west, the system it is going into is limited in capacity from the Niles border to the Des Plaines River. The water essentially hits a wall and collects along the border on Western, Sunset, Bruce, Carol, etc. It was explained that when the sewer system to the west is at capacity, stormwater from Niles begins to overwhelm the sewers becoming overland flow impacting streets, yards, and homes. It was explained that the only option for this area is developing a storage system to hold excess stormwater until it can slowly be released into the sewer system to the west.
On the east side of the Phase I study area, it is a different story. On the east side it is a matter of developing sewers that can convey more capacity away to the North Branch of the Chicago River or the Metropolitan Water Reclamation District (MWRD) system. Both the west and east side recommendations have obstacles to include areas to create stormwater storage and funding.
The recommended comprehensive stormwater program includes four parts: a) Cost Share Programs; b) Maintenance and Monitoring; c) Regulatory Program; and d) Capital Improvements.
a) The Stormwater Commission is recommending an annual $450,000 Cost Share Program which includes:
d) The Stormwater Commission has identified nine preliminary conveyance and storage capital projects for Phase I that are projected to cost between $20 million to $36 million. Once Phase II of the study is completed, this will likely result in five to eight more projects totaling $5 million to $10 million for a total cost of between $25 million to $46 million.
So what is next? Beginning in November 2011, the Stormwater Commission will begin to identify small projects, while Hey and Associates begins their Phase II analysis of the sewer system. The goal is to conduct a public open house by the end of February 2012 and to finish a draft master plan for approval and implementation in May 2012.
Updated 10/27/2011
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Jeff Wickenkamp of Hey and Associates began by showing the Phase I and Phase II analysis areas and the first modeling overview. This was followed by an explanation of historical rainfall depths and the types of rains (by frequency and duration) that most negatively impact the village’s sewer system. Since 1987, there were three 100-year storms (storms with 1% chance of occurring in any year). The 1987 and 2008 storms were similar (a lot of rainfall over a longer period of time), but the 2011 storm had only an inch less of rainfall in only two hours time.
The topography found on the west and east side of the Phase I study area was discussed.
On the west side, stormwater flows from east to west toward Park Ridge and unincorporated Cook County. This main issue with this flooding is due to downstream flow. No matter how big the pipes are to carry away stormwater toward the west, the system it is going into is limited in capacity from the Niles border to the Des Plaines River. The water essentially hits a wall and collects along the border on Western, Sunset, Bruce, Carol, etc. It was explained that when the sewer system to the west is at capacity, stormwater from Niles begins to overwhelm the sewers becoming overland flow impacting streets, yards, and homes. It was explained that the only option for this area is developing a storage system to hold excess stormwater until it can slowly be released into the sewer system to the west.
On the east side of the Phase I study area, it is a different story. On the east side it is a matter of developing sewers that can convey more capacity away to the North Branch of the Chicago River or the Metropolitan Water Reclamation District (MWRD) system. Both the west and east side recommendations have obstacles to include areas to create stormwater storage and funding.
The recommended comprehensive stormwater program includes four parts: a) Cost Share Programs; b) Maintenance and Monitoring; c) Regulatory Program; and d) Capital Improvements.
a) The Stormwater Commission is recommending an annual $450,000 Cost Share Program which includes:
- Flood control systems
- 50/50 cost share with a maximum benefit of $5,000 for an overhead sewer or backflow prevention valve installation.
- Green infrastructure
- Rain barrels at a reduced $25 price.
- 50/50 cost share with a maximum benefit of $2,000 for the construction of a rain garden.
- Floodproofing
- 50/50 cost share with a maximum benefit of $10,000 for wet or dry floodproofing of buildings.
- Local drainage improvements
- Engineering and/or construction of street or lot level drainage improvements.
- Program management
- Funds for the work associated with stormwater program management, cost share implementation, and resident assistance programs.
- Slip lining sewers
- Continue the sanitary slip lining program.
- Sewer inspection
- Continue the sewer identification and inspection program.
- Sewer monitoring
- Conduct sewer monitoring for key subareas experiencing the highest sanitary sewer backups to determine the amount of stormwater infiltration and inflow.
d) The Stormwater Commission has identified nine preliminary conveyance and storage capital projects for Phase I that are projected to cost between $20 million to $36 million. Once Phase II of the study is completed, this will likely result in five to eight more projects totaling $5 million to $10 million for a total cost of between $25 million to $46 million.
So what is next? Beginning in November 2011, the Stormwater Commission will begin to identify small projects, while Hey and Associates begins their Phase II analysis of the sewer system. The goal is to conduct a public open house by the end of February 2012 and to finish a draft master plan for approval and implementation in May 2012.