VILLAGE OF LAKE BLUFF

Transcription

1 VILLAGE OF LAKE BLUFF FINANCE COMMITTEE Monday, April 6, :00 PM VILLAGE HALL BOARD ROOM 40 E. CENTER AVE, LAKE BLUFF, IL AGENDA I. Call to Order Roll Call Trustee Steve Christensen, Chairman Trustee Brian Rener, Member Trustee Mark Dewart, Member II. Approval of Minutes March 9, 2015 III. Non-Agenda Items and Visitors The Finance Committee allocates fifteen (15) minutes at this time for those individuals who would like the opportunity to address the Committee on any matter not listed on the agenda. IV. Business Items 1. Presentation Regarding Stormwater Flooding Relief Studies V. Informational Item VI. Adjournment The Village of Lake Bluff is subject to the requirements of the Americans with Disabilities Act of Individuals with disabilities who plan to attend this meeting and who require certain accommodations in order to allow them to observe and/or participate in this meeting, or who have questions regarding the accessibility of the facilities, are requested to contact R. Drew Irvin at or TDD number promptly to allow the Village of Lake Bluff to make reasonable accommodations.

2 VILLAGE OF LAKE BLUFF - FINANCE COMMITTEE MINUTES OF MEETING March 9, 2015 I. Call to Order Roll Call The Finance Committee of the Village of Lake Bluff was called to order on Monday, March 9, 2015 at 6:00 PM in the Village Hall Board Room, 40 E. Center Ave., Lake Bluff, Illinois. Members Present: Trustee Steve Christensen, Chairman Trustee Brian Rener, Member Trustee Mark Dewart, Member Others Present: Kathleen O Hara, Village Board President Barbara Ankenman, Village Clerk Eric Grenier, Village Board Trustee John Josephitis, Village Board Trustee (arrived at 6:15) William Meyer, Village Board Trustee R. Drew Irvin, Village Administrator Susan Griffin, Finance Director Marlene Scheibl, Assistant Finance Director Brandon Stanick, Assistant to the Village Administrator Michael Croak, Building Code Supervisor Jake Terlap, Public Works Superintendent II. Approval of Minutes Member Dewart moved to approve the minutes of the February 21, 2015 meeting as presented; seconded by Member Rener and approved unanimously on a voice vote. III. Business Items 1. Discussion Regarding Possible Village Canopy Tree Planting Program PW Superintendent Terlap said the purpose of a tree planting program would be to provide monetary assistance to residents who have lost trees due to Emerald Ash Borer, or other circumstances, and would like to replace trees on their private property. Two types of programs that could be considered are a cost share program or a tree sale. In a cost share program the resident could purchase and plant the trees and the Village could match a portion of their expense or Public Works could plant the trees, but this option would involve much more time and labor from the Public Works staff. If the Village held a tree sale for residents who had lost trees, the program would be much more owner driven. The owner would pick up the trees and plant the trees themselves. These would be small trees about one and a half inch around and in a burlap bag. Public Works could have an Open House at its facility on the same day as the tree sale. The Village tree permits would provide information on tree replacements. Member Rener asked how much of a discount the Village would receive on the cost of the trees. PW Superintendent Terlap said it is hard to say because we would negotiate the price of the trees based on the quantity purchased. Chairman Christensen suggested we add money to the budget for this program and see if this event could take place at Public Works this fall. The consensus of the committee was to add $4,000 to the FY16 tentative budget to purchase trees for the tree planting program. Page 1 of 2

3 Village of Lake Bluff Finance Committee Minutes March 9, Discussion Regarding Village Travel Reimbursement Policy VA Irvin stated the Village has adopted a policy regarding travel reimbursements for Village employees, but all other individuals who perform volunteer services on behalf of the Village are not subject to this policy. With a planned trip to the state capital by Village President O Hara to advocate on behalf of the Village, the Finance Committee should discuss use of this same policy to reimburse President O Hara and possibly, other Village volunteers as they travel for Village business. Member Dewart asked who would approve the expenditures. President O Hara responded the expenses would be approved by the Village Board. The item would appear as an Agenda Item for the Village Board and would be public record. VA Irvin suggested it could be added to the policy with it applying to Elected Officials. 3. Discussion Regarding Tentative Budget VA Irvin said the Village had received the Scranton/Route 176 Viaduct and Campbell Court storm water planning studies by Christopher Burke Engineering late on Friday. Village Engineer Russell had sent Christopher Burke is waiting for replies to his queries on the reports. The flooding issue at Scranton & Route 176 does not appear to have a quick inexpensive solution. VA Irvin said the Village has had recent discussions with the City of Lake Forest Engineering staff about jointly working on connecting pedestrian systems at the intersection of Sheridan Road and Moffett Road. The new section of sidewalk would run along the east side of Moffett Road at the extreme south end of the Village to connect with the City of Lake Forest s northerly walk extension. Village staff recommends inclusion of this project in the FY16 budget, particularly since Lake Forest is offering to split the cost. The cost to install the sidewalk will be about $60,000 with the Village half being $30,000. The second reading of the budget ordinance is scheduled for March 23 rd so there is still time to make adjustments to the budget, if necessary. This would be an addition to the budget. The members agreed to recommend inclusion of $30,000 into the FY2016 tentative annual budget. 4. Executive Session Personnel Matters Member Rener made a motion to enter into Executive Session to discuss Personnel at 6:35 PM, seconded by Member Dewart and all members voted aye. Chairman Christensen made a motion to adjourn the Executive Session at 6:45PM, seconded by Member Rener and all members voted aye. IV. Next Meeting The next meeting will be scheduled as needed. V. Adjournment Member Rener made a motion to adjourn the meeting at 6:47 PM, seconded by Member Dewart and all members voted aye. Respectfully submitted, Marlene Scheibl Assistant Director of Finance Page 2 of 2

4 VILLAGE OF LAKE BLUFF Memorandum To: From: Subject: Lake Bluff Finance Committee George Russell, Lake Bluff Village Engineer Review of Initial Draft Drainage Studies West Scranton Avenue Underpass Campbell Court Subdivision Date: April 3, 2015 As a result of the severe rain storm event experienced by the Village of Lake Bluff on May 12, 2014, the Village engaged the services of Christopher B. Burke Engineering, Ltd. (Christopher Burke) to perform two separate drainage investigations of the two more significant flood impacted areas of the Village. These areas are the West Scranton Avenue Underpass and the Campbell Court Subdivision area. Christopher Burke has recently submitted an initial draft report to the Village for each of the two areas that were studied. A copy of each of the reports is attached. At Monday evening s Finance Committee meeting Mr. Darren Olsen of Christopher Burke will be present to review with the Finance Committee the findings of the two investigations. Mr. Olsen will also recommend next steps that may be taken to further evaluate the various remedial options under consideration prior to the Village selecting and commencing with detailed designs of selected alternatives.

5 WEST SCRANTON AVENUE VIADUCT DRAINAGE ANALYSIS VILLAGE OF LAKE BLUFF LAKE COUNTY, IL Prepared for: Village of Lake Bluff 40 E. Center Avenue Lake Bluff, IL February 2015 Prepared by: Christopher B. Burke Engineering, Ltd W. Higgins Road Suite 600 Rosemont, Illinois CBBEL Project No

6 West Scranton Ave Viaduct Drainage Analysis February 2015 TABLE OF CONTENTS TABLE OF CONTENTS... i LIST OF EXHIBITS... ii LIST OF APPENDICES... ii EXECUTIVE SUMMARY... 1 INTRODUCTION... 1 HYDROLOGIC AND HYDRAULIC ANALYSIS... 2 EXISTING CONDITIONS... 2 PROPOSED CONDITIONS... 3 ALTERNATIVE YEAR STORM SEWER FROM VIADUCT TO LAKE MICHIGAN... 4 ALTERNATIVE 2 10-YEAR STORM SEWER FROM VIADUCT TO LAKE MICHIGAN... 5 ALTERNATIVE 3 STORMWATER STORAGE BASIN UPSTREAM OF VIADUCT... 6 SUMMARY OF RESULTS... 8 i

7 West Scranton Ave Viaduct Drainage Analysis February 2015 LIST OF EXHIBITS 1. Site Location Map 2. USGS Quad Map 3. Existing Conditions Exhibit 10-Year Storm Event 4. Existing Conditions Exhibit 100-Year Storm Event 5. May 2014 Rainfall Event Inundation Exhibit 6. Proposed Condition Alternative 1 Exhibit 7. Proposed Condition Alternative 1A Exhibit 8. Proposed Condition Alternative 2 Exhibit LIST OF APPENDICES 1. Hydrologic Parameters Calculations 2. Engineer s Estimates of Probable Cost 3. CD-ROM with XP-SWMM Models and Supporting Data ii

8 West Scranton Ave Viaduct Drainage Analysis February 2015 EXECUTIVE SUMMARY The West Scranton Avenue Viaduct (Viaduct) Drainage Analysis was initiated by the Village of Lake Bluff in response to frequent flooding of the Viaduct. The results of the engineering study show that the Viaduct floods during events greater than or equal to the 1-year return interval storm event. During more severe events such as the 100-year design storm event, the viaduct would be flooded up to 7 feet deep and would remain flooded for up to 40 hours. As part of this study, following three drainage improvement alternatives were developed to reduce the risk of flooding in the Viaduct: Alternative Year Storm Sewer from Viaduct to Lake Michigan: Under this alternative, a 48-inch diameter storm sewer would be installed from the Viaduct to Lake Michigan under North Avenue. This would provide a 100-year level of protection for the Viaduct and the engineer s estimate of probable cost is $18.2M. Alternative 2 10-Year Storm Sewer from Viaduct to Lake Michigan: Under this alternative, a 30-inch diameter storm sewer would be installed from the Viaduct to Lake Michigan under North Avenue. This alternative would provide a 10-year level of protection for the Viaduct and the engineer s estimate of probable cost is $3.4M. Alternative 3 Stormwater Storage Upstream of Viaduct: Under this alternative, a stormwater storage basin would be constructed upstream of the Viaduct to reduce the flowrate of water toward the Viaduct. This alternative would provide a 10-year level of protection for the Viaduct and the engineer s estimate of probable cost is $1.6M. Each alternative will require permitting through various regulatory agencies, with Alternatives 1 and 2 requiring the most regulatory review due to the proximity of the proposed alternatives to Lake Michigan. Upon selection of a preferred alternative, it is recommended that additional data collection such as detailed topographic survey and geotechnical borings be completed in addition to meeting with regulatory agencies and stakeholders. Using this information, additional preliminary engineering will be required to refine the concept design for the selected alternative. INTRODUCTION This report summarizes a Christopher B. Burke Engineering, Ltd. (CBBEL) analysis for the West Scranton Avenue Viaduct Drainage Analysis. The Viaduct is located is located in the Village of Lake Bluff (Village), Lake County, Illinois. The purpose of this study was to determine the current level of protection the Viaduct and to develop drainage improvement alternatives that will increase the level of flood protection. The Viaduct is the only permanent access road for emergency vehicles to cross the Union Pacific Railroad (UPRR) tracks within the Village and closure of the Viaduct results in health and safety concerns. An exhibit showing the location of the Viaduct is shown on Exhibit 1. The USGS Quadrangle Map showing the project location is included as Exhibit 2. There is no mapped floodplain at the Viaduct according to the Federal Emergency Management Agency (FEMA) Flood Insurance Rate Map (FIRM) for Lake County. 1

9 West Scranton Ave Viaduct Drainage Analysis February 2015 Existing Conditions HYDROLOGIC AND HYDRAULIC ANALYSIS The Viaduct is drained by a 24-inch diameter clay storm sewer that was constructed in 1903 and discharges to the ravine east of Evanston Road and north of Sylvan Road. The clay storm sewer has been inspected recently and determined to be in satisfactory condition. However, the ravine downstream of the outfall has experienced significant erosion problems in the past and the Village recently completed channel stabilization work to protect existing infrastructure and properties adjacent to the ravine. The direct tributary area to the Viaduct is approximately 103 acres under normal flow conditions when storm sewers convey runoff toward the Viaduct during typical rainfall events. The direct tributary area is bound by Green Bay Road to the west, Washington Avenue to the north, Park Lane to the south and the UPRR tracks to the east. During larger storm events, the tributary area can increase to 222 acres when the storm sewer system in areas outside of the direct tributary becomes surcharged and overland flow is directed toward the Viaduct. Under these conditions, the tributary area includes portions of the Bath and Tennis Club subdivision and other areas adjacent to the railroad tracks. An existing conditions hydrologic and hydraulic model was developed using XP-SWMM software. The XP-SWMM software is a dynamic modeling program that calculates the hydrologic response (Runoff Mode) from a storm event and routes the runoff through a storm sewer network and overland drainage system (Hydraulics Mode). The XP-SWMM software was chosen for this analysis as it is able to simulate surcharged storm sewer systems overland flow and surface storage using the St. Venant equations for unsteady flow. This software was originally developed by the U.S. Environmental Protection Agency (USEPA) for analyzing urban flooding and is widely used locally and nationally in this capacity. The XP-SWMM model for the Viaduct was developed based on site visits, Lake County 1-foot aerial topography, aerial photography, soils mapping, Village storm sewer atlas and site specific survey. The site specific survey was performed by Thomson Surveying, Ltd. and included the rim elevations of catch basins, storm sewer inverts and pipe diameters of the existing storm sewer system. The tributary area to the Viaduct was divided into approximately 20 subbasins and the Runoff Curve Number (RCN) and Time of Concentration (t c ) for each subbasin were calculated using National Resources Conservation Services (NRCS) methodologies. These calculations are provided in Appendix 1. A critical duration analysis was performed to determine the critical peak elevations for both the Viaduct and the East Terrace subdivision using Lake County rainfall data and Huff rainfall distributions. The results of the critical duration analysis show that the 2-hour design storm event is the critical duration event for the East Terrace subdivision storm sewer system and the 18-hour design storm event is the critical duration event for the Viaduct. The May 2014 rainfall event was also analyzed as a verification storm event for the model. During this event, 3-inches of rain fell over a 5.5 hour time period resulting in the Viaduct closing for approximately 12 hours from May 12 th 13 th. This event was approximately equivalent to a 2

10 West Scranton Ave Viaduct Drainage Analysis February year recurrence interval storm event. The results of XP-SWMM model for the May 2014 storm event match closely with the depth and duration of flooding reported by Village staff. The May 2014 inundation exhibit is included as Exhibit 5. The results of the existing conditions analysis are summarized in Table 1. The table provides the peak water surface elevation at the Viaduct and also the drawdown time to get to an elevation below the lowest pavement elevation of approximately.0 ft. An exhibit showing the existing conditions inundation area for the 10-year storm event and 100-year storm event is included as Exhibit 3 and Exhibit 4 respectively. TABLE 1 Existing Conditions XP-SWMM Model Results Peak Water Surface Elevation and Drawdown Time at Viaduct* Return Interval Storm Event Elevation (ft) Depth of Flooding (ft) Drawdown Time (Hours) 1-Year Year Year Year Year Year May *Low pavement elevation in underpass =.0 ft **18-hour critical duration design storm event The results of the existing conditions drainage system determined that the existing 24-inch diameter storm sewer draining the Viaduct provides less than a 1-year level of protection as it is undersized given the tributary area to the Viaduct. This is consistent with the frequent flooding of the Viaduct that has been reported by Village staff and seen in May and June Proposed Conditions The proposed conditions analysis identified three drainage improvement alternatives that will increase the level of flood protection for the Viaduct. The alternatives were developed to a concept level that allowed for incorporation of the improvements into the XP-SWMM model to identify project benefits as well as preparation of an engineer s estimate of probable cost. The proposed projects consist of conveyance improvements to remove water from the Viaduct faster and upstream flood storage upstream to reduce the rate at which water enters the Viaduct. The three alternatives evaluated as part of the Viaduct improvements include the following: A new 48-inch diameter storm sewer to convey stormwater from the Viaduct to Lake Michigan that will provide a 100-year level of protection for the Viaduct. 3

11 West Scranton Ave Viaduct Drainage Analysis February 2015 A new 30-inch diameter storm sewer to convey stormwater from the Viaduct to Lake Michigan that will provide a 10-year level of protection for the Viaduct. A flood storage basin located upstream of the Viaduct that will provide a 10-year level of protection for the Viaduct. Based on the recent stabilization and current condition of the ravine system downstream of the existing 24-inch storm sewer outfall, additional conveyance improvements directed toward the ravine system were ruled out as a proposed drainage improvement. Alternative Year Relief Storm Sewer from Viaduct to Lake Michigan The first alternative consisted of a new 48-inch diameter relief storm sewer from the Viaduct to Lake Michigan. The existing 24-inch storm sewer draining the Viaduct would remain in service and will continue to drain the Viaduct in addition to the proposed storm sewer. The alignment of the proposed storm sewer will be west of Sheridan Road, within the open space and east towards Lake Michigan within the North Avenue Right of Way (ROW). Due to the depth of the proposed storm sewer, it is proposed to be installed using tunneling methodologies rather than open cutting of the streets. At the western limits of Lillian Dells, the proposed 48-inch storm sewer will be installed in the ravine via open cut and will connect to a new 60-inch diameter outfall pipe to Lake Michigan. The 60-inch diameter outfall pipe will replace the existing 48-inch outfall pipe currently draining the existing storm sewer from the intersection of East Washington Avenue and Maple Avenue. The proposed 48-inch diameter storm sewer has been sized to convey the 100-year storm event for the Viaduct and will allow for future storm sewer connections within East Lake Bluff that will provide flood reduction benefits to this area as well. In addition to the improvements described above, Alternative 1 also included the minor storm sewer improvements at Lincoln Avenue and Hancock Avenue previously designed by the Village. The results of the Alternative 1 analysis are summarized in Table 2. TABLE 2 Alternative 1 XP-SWMM Model Results Peak Water Surface Elevation at the Viaduct* Return Interval Storm Event** Existing Conditions (ft) Proposed Conditions (ft) Difference (ft) 1-Year Year Year Year Year Year *Low pavement elevation in underpass =.0 ft **18-hour critical duration design storm event 4

12 West Scranton Ave Viaduct Drainage Analysis February 2015 Alternative 1 will provide a 100-year level of protection for the Viaduct and will allow the road to remain open during severe rainfall events up to and including the 100-year storm event. The proposed storm sewer alignment for Alternative 1 is included as Exhibit 6. The engineer s opinion of probable cost for Alternative 1 is $18.2M as shown in Appendix 2. The estimate does not include the minor storm sewer improvements at Lincoln Avenue previously designed by the Village. This alternative will likely require permitting through the Lake County Stormwater Management Commission (SMC), Illinois Department of Transportation (IDOT), the Illinois Environmental Protection Agency (IEPA), the Illinois Department of Natural Resources (IDNR), the U.S. Army Corps of Engineers (USACE) and other regulatory agencies. The construction of a replacement outfall to Lake Michigan is required as part of this alternative. This may be considered maintenance by the regulatory agencies or it may be considered as a new outfall to the lake. Based on this determination, extensive water quality treatment of the stormwater may be required prior to discharge to the lake. The water draining through the proposed storm sewer outfall will likely improve water quality to the lake as it will not contribute to erosion of the existing ravine system at the current storm sewer outfall from the Viaduct. However, the specific water quality treatment measures required cannot be quantified until the concept is presented to the regulatory agencies, and a 30% contingency was included in the estimate of cost to reflect the potential need for water quality measures as part of this alternative. Alternative 2 10-Year Relief Storm Sewer from Viaduct to Lake Michigan Alternative 2 is similar to the previously discussed Alternative 1, but the level of protection for the Viaduct is proposed to be a 10-year level of protection rather than a 100-year level of protection. A 30-inch diameter relief storm sewer is proposed to provide a 10-year level of protection for the Viaduct. The existing 24-inch storm sewer draining the Viaduct would remain in service and will continue to drain the Viaduct in addition to the proposed storm sewer. In addition to the reduction in flooding frequency, this alternative will also greatly reduce the drain down time during storm events greater than the 10-year event. Due to the depth of the proposed storm sewer, it is proposed to be installed using Horizontal Directional Drilling (HDD) methods. Based on our discussions with several HDD contractors, a 30-inch diameter storm sewer is the largest diameter that can be installed using these methods. Similar to Alternative 1, the proposed storm sewer will installed in the ravine at the eastern limits of the project via open cut and will connect to a new 60-inch diameter outfall pipe to Lake Michigan. The 60-inch diameter outfall pipe will replace the existing 48-inch outfall pipe currently draining the existing storm sewer from the intersection of East Washington Avenue and Maple Avenue. The proposed 30-inch diameter storm sewer has been sized to convey the 10-year storm event for the Viaduct and will allow for future storm sewer connections within East Lake Bluff that will provide flood reduction benefits to this area as well. In addition to the improvements described above, Alternative 2 also included the minor storm sewer improvements at Lincoln Avenue and Hancock Avenue previously designed by the Village. The proposed storm sewer alignment for Alternative 2 is included as Exhibit 7. The results of the XP-SWMM analysis for Alternative 2 are provided in Table 3. 5

13 West Scranton Ave Viaduct Drainage Analysis February 2015 Return Interval Storm Event** TABLE 3 Alternative 2 XP-SWMM Model Results Peak Water Surface Elevation and Duration of Flooding at Viaduct* Existing Conditions (ft) Proposed Conditions (ft) Difference (ft) Existing Conditions Drawdown Time (Hours) Proposed Conditions Drawdown Time (Hours) Difference (Hours) 1-Year Year Year Year Year Year *Low pavement elevation in underpass =.0 ft **18-hour critical duration design storm event The results of the XP-SWMM analysis show that a 30-inch diameter storm sewer from the Viaduct to Lake Michigan is capable of providing a 10-year level of protection but less than the 50-year level of protection. This alternative will also decrease the time the underpass is inundated with stormwater and impassable. Exhibit 7 shows the proposed alignment of Alternative 2. The engineer s opinion of probable cost for Alternative 2 is $3.4M as shown in Appendix 2. The estimate does not include the minor storm sewer improvements at Lincoln Avenue previously designed by the Village. Similar to Alternative 1, this alternative will likely require permitting through the Lake County Stormwater Management Commission (SMC), Illinois Department of Transportation (IDOT), the Illinois Environmental Protection Agency (IEPA), the Illinois Department of Natural Resources (IDNR), the U.S. Army Corps of Engineers (USACE) and other regulatory agencies. The construction of a replacement outfall to Lake Michigan is required as part of this alternative. This may be considered maintenance by the regulatory agencies or it may be considered as a new outfall to the lake. Based on this determination, extensive water quality treatment of the stormwater may be required prior to discharge to the lake. The water draining through the proposed storm sewer outfall will likely improve water quality to the lake as it will not contribute to erosion of the existing ravine system at the current storm sewer outfall from the Viaduct. However, the specific water quality treatment measures required cannot be quantified until the concept is presented to the regulatory agencies, and a 30% contingency was included in the estimate of cost to reflect the potential need for water quality measures as part of this alternative. Alternative 3 Stormwater Storage Basin Upstream of Viaduct Alternative 3 consists of the construction of a proposed stormwater storage basin northeast of the intersection of West Center Avenue and Mawman Avenue on Village owned property. The storage basin is designed to reduce the peak flowrate into the Viaduct by capturing and 6

14 West Scranton Ave Viaduct Drainage Analysis February 2015 temporarily storing runoff from the upstream tributary area and releasing it slowly toward the Viaduct. The stormwater storage basin will be approximately 16 feet deep with 3:1 side slopes and will provide approximately 10 acre-ft of stormwater storage as shown on Exhibit 8. The stormwater storage basin will connect to the existing storm sewer system draining toward the Viaduct through a 6-inch restrictor. In addition to the improvements described above, Alternative 3 also included the minor storm sewer improvements at Lincoln Avenue and Hancock Avenue previously designed by the Village. The XP-SWMM results for Alternative 3 are summarized in Table 4. Return Interval Storm Event** TABLE 4 Alternative 3 XP-SWMM Model Results Peak Water Surface Elevation* and Duration of Flooding at Viaduct Existing Conditions (ft) Proposed Conditions (ft) Difference (ft) Proposed Stormwater Storage Basin High Water Level (ft) Existing Conditions Drawdown Time (Hours) Proposed Conditions Drawdown Time (Hours) Difference (Hours) 1-Year Year Year Year Year Year *Low pavement elevation in underpass =.0 ft **18-hour critical duration design storm event As shown in Table 4, this alternative provides a 10-year level of protection for the Viaduct. It is not possible to provide a higher level of protection with flood storage at this location given the 28 acres of tributary area that is directly tributary to the Viaduct. The proposed stormwater storage basin will also provide flood reduction benefits for events greater than the 10-year return interval design storm event, but the reductions in depth and duration of inundation are less than under Alternative 2. The engineer s opinion of probable cost for Alternative 3 is $1.6M as shown in Appendix 2. The estimate does not include the minor storm sewer improvements at Lincoln Avenue previously designed by the Village. This alternative may require permitting through the Lake County Stormwater Management Commission (SMC), Illinois Department of Transportation (IDOT), the Illinois Environmental Protection Agency (IEPA) and other regulatory agencies. As reflected in the engineer s estimate of probable cost, this alternative will require relocation of existing water and sanitary sewer lines in the vicinity of the stormwater storage basin and will required significant tree removal. The permitting for this alternative would be less complex than Alternatives

15 West Scranton Ave Viaduct Drainage Analysis February 2015 SUMMARY OF RESULTS This report summarizes the results of the West Scranton Avenue Viaduct Drainage Analysis in the Village of Lake Bluff. The three alternatives analyzed will increase the level of protection for the Viaduct from the 1-year storm event under existing conditions to a minimum of the 10-year storm event. Each alternative will also eliminate or decrease the time that the road is closed to vehicular traffic due to flooding. Alternative 1 and 2 include conveyance improvements with a relief storm sewer, which will greatly reduce the drawdown time of the Viaduct. Alternative 3 provides a stormwater storage option that will reduce peak flowrates entering the Viaduct. The alternatives range in cost from $1.6M to $18.2M depending on the level of flood protection provided. Upon selection of a preferred alternative, it is recommended that additional data collection such as detailed topographic survey and geotechnical borings be completed in addition to meeting with regulatory agencies and stakeholders. As the project involves roadway drainage related to Illinois Route 176, the results of this study should be provided to IDOT for review. While the proposed alternatives may not meet the IDOT requirements for subway conditions, each will provide a significant benefit as compared to existing conditions. Upon completion of these items, additional preliminary engineering will be required to refine the concept design of the preferred alternative. JSG N:\LakeBluff\140491\Water\Docs\r doc 8

16 Sheridan Oak I Feet 1 inch = 200 feet Washington Rockland Mawman North Walnut Scranton IL Route 176 Scranton Project Location Center Center Mawman Path: N:\LakeBluff\140491\Water\0215Report\Exhibit\Ex1.mxd CLIENT: Village of Lake Bluff TITLE: Site Location Map DSGN. SCALE: 1:0 DWN. AUTHOR: CHKD. PLOT DATE: 2/27/2015 FILE: Ex1 PROJ. NO. DATE: SHEET 1 OF 1 DRAWING NO. EXH 1

17 Oak Oak Oak Hirst Foss Blodgett Blodgett I 0 Blodgett Feet 1 inch = 600 feet Main Woodland Green Bay IL Route 131 Garfield Pine Lincoln Rockland Mawman Washington Hancock North Scranton IL Route 176 Project Location Scranton Thornwood Center Center Glen Birkdale Prospect Pine Lincoln Rockland Mawman Prospect Evanston Sylvan Sheridan Park Circle Vincent Newman Hawthorne Witchwood Hickory Witchwood Jensen Clay Wimbledon Ravine Forest Hawthorne Forest Hills Sunset Path: N:\LakeBluff\140491\Water\0215Report\Exhibit\Ex2.mxd CLIENT: Village of Lake Bluff TITLE: Mckinley Indian USGS Quadrangle Map Sheridan DSGN. SCALE: 1:0 DWN. AUTHOR: CHKD. PLOT DATE: 2/27/2015 FILE: Ex2 PROJ. NO. DATE: SHEET 1 OF 1 DRAWING NO. EXH 2

18 Tara Oak Sheridan Edgewood Oak Oak Hirst Foss N Feet 1 inch = 500 feet Armour Blodgett Bradford Brierfield Blodgett Blodgett Legend Crabtree 10-Year Inundation Overland Flow Path Subbasin Divide StormSewer Ravine Manhole / Structure Sunset Rockland Thornwood Birkdale Prospect Sunset IL Route 131 ID: 432 ID: 433 ID: 436 ID: 445 ID: 419 ID: 721 ID: 257 ID: 430 ID: 423 ID: 425 ID: 431 Sheridan Hawthorne Garfield Pine Pine Lincoln IL Route 176 Center ID: 424 Lincoln ID: 723 ID: 484 Scranton Rockland Park Rockland ID: 415 Main ID: 407 Mawman Mawman ID: 410 ID: 421 ID: 738 ID: 434 ID: 273 ID: 736 ID: 272 ID: 735 ID: 440 Woodland Washington Walnut Circle Center Witchwood ID: 555 North Scranton Evanston Ravine Glen Prospect Sylvan Vincent Newman Glen Clay Wimbledon Ravine Forest Jensen Bath And Tennis Club Forest Hills ID: 734 Hawthorne Sunset Indian Green Bay Park Oxford Greenleaf Alden Mckinley Willow Western Winthrop DSN. CL IEN T: TITLE: PR O J. N O CHKD. Village of Lake Bluff No. DATE NATURE OF REVISION FILE NAME: DATE: SCALE GIS USER MODEL ArcGIS Year Storm Event Flood Inundation Map SH EET 1 O F 1 DR AW I NG N O. EXH 3

19 Eva Tara Oak Oak Oak Hirst Foss N Feet 1 inch = 500 feet Sunset Rockland Thornwood Birkdale Prospect Sunset IL Route 131 Armour ID: 432 ID: 430 Garfield ID: 431 ID: 433 Sheridan Hawthorne Blodgett ID: 436 ID: 445 ID: 425 Jensen Pine Pine ID: 419 Lincoln IL Route 176 Center ID: 424 Lincoln ID: 721 ID: 257 ID: 723 ID: 423 ID: 484 Scranton Park Brierfield Blodgett Rockland Rockland ID: 440 ID: 415 Main ID: 407 Mawman Mawman ID: 272 ID: 410 ID: 421 ID: 738 ID: 434 Clay Wimbledon ID: 273 Blodgett ID: 736 ID: 735 Woodland Washington Walnut Circle ID: 555 Center Witchwood North Evanston Ravine Forest Ravine Sheridan Vincent Legend Scranton Subbasin Divide Glen Prospect 100-Year Inundation Overland Flow Path RAVINE StormSewer Manhole / Structure Sylvan Newman ID: 734 Hawthorne Bath And Tennis Club Forest Hills Sunset ID: 270 Indian Green Bay Park Oxford Greenleaf Alden Mckinley Willow Winthrop Burr Oak Western DSN. CL IEN T: TITLE: PR O J. N O CHKD. Village of Lake Bluff No. DATE NATURE OF REVISION FILE NAME: DATE: SCALE GIS USER MODEL ArcGIS Year Storm Event Flood Inundation Map SH EET 1 O F 1 DR AW I NG N O. EXH 4

20 12 In. Tara Oak Edgewood Oak Oak Hirst Foss N Feet 1 inch = 500 feet Rockland IL Route 131 Thornwood Sunset Birkdale Prospect Armour ID: 433 ID: In. Garfield ID: 430 ID: 425 ID: 431 Sheridan Hawthorne Blodgett Scranton Pine ID: 436 Center ID: 445 Pine Lincoln ID: In. 8 In. ID: 419 ID: 424 ID: 721 IL Route 176 Lincoln ID: 423 ID: In. Park ID: 415 ID: 723 ID: 440 Brierfield Blodgett Rockland Rockland Main ID: 407 ID: 410 ID: 421 ID: 738 ID: 434 Mawman 15 In. 18 In. Mawman 36 In. 24 In. 30 In. ID: 736 ID: 273 ID: 735 Woodland Washington Walnut Circle Witchwood Evanston Blodgett Ravine North Scranton 24 In. Sheridan Center Glen Sylvan Vincent Newman Legend Crabtree Overland Flow Path Subbasin Divide May 2014 Inundation StormSewer Ravine Manhole / Structure Prospect Briar Clay Wimbledon Ravine Forest Jensen Bath And Tennis Club Forest Hills ID: 734 Hawthorne Sunset Crescent ID: 270 Indian Green Bay Alden Mckinley Park Oxford Greenleaf Willow Ravine Park Spruce Winthrop Burr Oak Western DSN. CL IEN T: TITLE: PR O J. N O CHKD. Village of Lake Bluff No. DATE NATURE OF REVISION FILE NAME: DATE: SCALE GIS USER MODEL ArcGIS 9.2 May 2014 Storm Event Flood Inundation Map SH EET 1 O F 1 DR AW I NG N O. EXH 5

21 Moffett Oak Hirst Foss 12 in. Gurney Maple Simpson Sunrise Oak Leeds Bradford Brierfield Crabtree I Feet 1 inch = 400 feet Blodgett Blodgett Blodgett Legend Proposed MH/Inlet Proposed Storm Sewer Washington Green Bay Garfield 8 in. 12-Inch Dia RCP Pine Pine Hancock 12 in. Lincoln 8 in. IL Route 176 Lincoln Center Sheridan 15 in. Rockland Rockland 15 in. Main 18 in. Mawman 48-Inch Dia RCP Tunnel Construction 24 in. 48-Inch Dia RCP Install High Capacity Storm Sewer Inlets 30 in. North Walnut Scranton Woodland Washington 48-Inch Dia RCP Tunnel Construction Evanston Ravine Scranton 24 in. Sheridan Glen Prospect Glen Center Sylvan Birch Remove Existing 48-inch Dia RCP Replace with 60-Inch Dia RCP Bluff 48-Inch Dia RCP Open Cut Construction Mountain Proposed Bus Drop-Off Existing MH/Junction Existing Storm Sewer Park Ravine Sunrise Park Mawman 36 in. 36 in. CL I EN T: Wimbledon Village of Lake Bluff Circle Witchwood Vincent Newman NO. DATE NATU R E OF R E VISI O N CH K D. FILE NAME Ex6 PATH N:\LakeBluff\140491\Water\0215Report\Exhibit\Ex6.mxd DS GN. DWN: CH K D. SC ALE : MO D EL : PLO T D ATE Briar 1:0 Arc G IS 10 2/27/2015 TIT LE : Lakeland Alternative 1: Relief Storm Sewer to Lake Michigan Tunnel Construction PR OJ. N O DATE: SH EET 0 O F 0 DR AWI N G N O. EXH 6

22 Moffett Oak Hirst Foss 12 in. Gurney Maple Simpson Sunrise Oak Leeds Bradford Brierfield Crabtree I Feet 1 inch = 400 feet Blodgett Blodgett Blodgett Legend Proposed MH/Inlet Proposed Storm Sewer Washington Green Bay Garfield 8 in. 12-Inch Dia RCP Pine Pine Hancock 12 in. Lincoln 8 in. Lincoln IL Route 176 Center Sheridan 15 in. Rockland Rockland 15 in. Main 18 in. Mawman 30-Inch Dia PVC HDD Construction 24 in. 30-Inch Dia RCP Install High Capacity Storm Sewer Inlets 30 in. Washington Walnut Scranton North Woodland 30-Inch Dia PVC HDD Construction Evanston Ravine Scranton 24 in. Sheridan Glen Prospect Glen Center Sylvan Birch Remove Existing 48-inch Dia RCP Replace with 60-Inch Dia RCP Bluff 30-Inch Dia PVC Open Cut Construction Mountain Proposed Bus Drop-Off Existing MH/Junction Existing Storm Sewer Park Ravine Sunrise Park Mawman 36 in. 36 in. CL I EN T: Wimbledon Village of Lake Bluff Circle Witchwood Vincent Newman NO. DATE NATU R E OF R E VISI O N CH K D. FILE NAME Ex7 PATH N:\LakeBluff\140491\Water\0215Report\Exhibit\Ex7.mxd DS GN. DWN: CH K D. SC ALE : MO D EL : PLO T D ATE Briar 1:0 Arc G IS 10 2/27/2015 TIT LE : Lakeland Alternative 2: Relief Storm Sewer to Lake Michigan Tunnel Construction PR OJ. N O DATE: SH EET 0 O F 0 DR AWI N G N O. EXH 7

23 Sheridan I Feet 1 inch = 100 feet North Legend Hancock Rockland 12 in. Mawman Proposed Basin Grading Proposed MH/Inlet Proposed Storm Sewer Existing MH/Junction Existing Storm Sewer Parcel Boundary Proposed 12-in Dia RCP 18 in. 12 in. Lincoln 8 in. Lincoln Center CL I EN T: Rockland 15 in. Village of Lake Bluff Scranton Proposed 18-in Dia RCP Storm Sewer Existing Storm Sewer To Be Removed 15 in. IL Route 176 Proposed 24-in Dia RCP Storm Sewer Mawman Connect to Existing Storm Sewer DS GN. NO. DATE NATU R E OF R E VISI O N CH K D. MO D EL : FILE NAME PATH Ex8 N:\LakeBluff\140491\Water\0215Report\Exhibit\Ex8.mxd DWN: CH K D. SC ALE : PLO T D ATE 1:0 24 in. Arc G IS 10 2/27/2015 Construct 10.1 ac-ft Stormwater Storage Basin NWL = ft HWL = ft TIT LE : Outlet Control Structure 6-inch Dia ft 6 foot ft 24-inch Dia RCP Outlet Pipe Existing Storm Sewer To Be Removed 24 in. Scranton Note: As part of Alternative 3 Existing water main and sanitary sewer will be relocated south of proposed basin Alternative 3: Stormwater Storage Basin and Proposed Storm Sewer PR OJ. N O. DATE: SH EET 0 O F 0 DR AWI N G N O EXH 8

24 CAMPBELL COURT DRAINAGE INVESTIGATION VILLAGE OF LAKE BLUFF Prepared for VILLAGE OF LAKE BLUFF 40 E. Center Avenue Lake Bluff, Illinois March 2015 Prepared by Christopher B. Burke Engineering, Ltd West Higgins Road Rosemont, Illinois CBBEL Project No

25 Campbell Court Drainage Investigation March 2015 TABLE OF CONTENTS Table of Contents... i List of Tables... ii List of Exhibits... ii List of Appendices... ii EXECUTIVE SUMMARY... 1 Chapter 1 PROJECT OVERVIEW Introduction... 2 Chapter 2 EXISTING CONDITIONS Data Collection XP-SWMM Analysis & Results Observations... 4 Chapter 3 PROPOSED CONDITIONS Alternative 1A Alternative 1B Alternative Alternative Alternative Chapter 4 CONCLUSIONS i

26 Campbell Court Drainage Investigation March 2015 LIST OF TABLES 1) Table 2-1 Existing Conditions XP-SWMM Results 2) Table 3-1 Alternative 1A XP-SWMM Results 3) Table 3-2 Alternative 1B XP-SWMM Results 4) Table 3-3 Alternative 2 XP-SWMM Results 5) Table 3-4 Alternative 3 XP-SWMM Results 6) Table 3-5 Alternative 4 XP-SWMM Results 7) Table 4-1 Engineer s Estimate of Probable Cost LIST OF EXHIBITS 1) Location Map 2) Existing Conditions 3) Alternative 1A Schematic 4) Alternative 1B Schematic 5) Alternative 2 Schematic 6) Alternative 3 Schematic 7) Alternative 4 Schematic LIST OF APPENDICES 1) Engineer s Estimate of Probable Cost 2) CD-ROM with XP-SWMM Models and Supporting Data ii

27 Campbell Court Drainage Investigation March 2015 EXECUTIVE SUMMARY Christopher B. Burke Engineering, Ltd. (CBBEL) has completed a drainage analysis of the area surrounding Campbell Court that experienced flooding during the May 12, 2014 storm event. The study area is shown on the location map provided as Exhibit 1. The Village of Lake Bluff (Village) requested that CBBEL evaluate existing conditions drainage patterns and identify drainage improvement alternatives to reduce the risk of future flooding at this location. The evaluation included gathering watershed drainage data and XP-SWMM simulation of the May 12, 2014 storm event and 10-, , and 100-year design storm events. An existing condition XP-SWMM model was developed for the watershed and calibrated to known High Water Marks (HWM) provided by residents for the May 2014 flooding event. The results of the existing conditions analysis show that the May 2014 storm event exceeded the capacity of the existing drainage system and floodwaters ponded in the rear yards of Campbell Court. Four drainage improvement alternatives were developed to reduce the risk of future flooding at the study area. Alternatives 1A and 1B propose to construct 4.0 ac-ft and 6.3 ac-ft stormwater storage basins as shown on Exhibits 3 and 4. Alternative 2 proposes to construct a diversion channel and approximately 7.1 acre-ft of new flood storage as shown on Exhibit 5. Alternative 3 proposes to excavate the existing berm behind Campbell Court residences and use a portion of the material to fill backyards as shown on Exhibit 6. Alternative 4 proposes to excavate approximately 2.5 acre-ft of new flood storage volume on the Tangley Oaks property as shown on Exhibit 7. The engineer s estimate of probable cost for each alternative is summarized below. Alternative Engineer's Estimate of Probable Cost 1A $2,479,700 1B $3,356,700 2 $2,400,800 3 $1,003,500 4 $1,235,700 Regardless of whether or not one of the drainage improvement project are constructed, each property owner that experienced flooding in the past should evaluate their property and implement flood proofing measures as necessary to reduce the risk of future flooding. CBBEL also recommends that any development upstream of the study area be required to provide stormwater detention as there is inadequate downstream capacity within the study area to accommodate additional runoff. Additionally, it is recommended that that Union Pacific Railroad (UPRR) ditch through the study area be cleaned on a regular basis to improve flow and lessen that chance of culvert blockage. The culverts under the UPRR and Sheridan Road should also be televised to verify their condition. 1

28 Campbell Court Drainage Investigation March 2015 CHAPTER INTRODUCTION PROJECT OVERVIEW The Village experienced flooding at the area surrounding Campbell Court during the May 12, 2014 storm event. Based on conversations with residents and Village staff, at least two structures were flooded from standing water in the rear yard entering the home through a window well or basement window. Several of the other properties reported high standing water in the rear yards. CBBEL was hired by the Village to evaluate the existing drainage system and to develop drainage improvement alternatives to reduce the risk of future flooding. The study area is shown on the location map provided as Exhibit 1 and in Figure 1-1 below. Figure 1-1 Project Location 2

29 Campbell Court Drainage Investigation March 2015 CHAPTER 2 EXISTING CONDITIONS 2.1 DATA COLLECTION The following items were used in the CBBEL study: CBBEL topographic survey completed in December 2014; Several CBBEL site visits; As-built plans titled Campbell Woods Subdivision Improvements last revised March 19, 1992; Report titled Arden Shores South Subdivision Phase II Drainage Study, Lake County, Illinois prepared by Fluid Clarity, dated October 2007; Plan set for Great Lakes Naval Base dated December 22, 2006; 30-minute interval rainfall data from the Lake Bluff Public Works Precipitation Gage for the May 12, 2014 storm event; Lake County 1-foot contour topography; 2013 Lake County aerial photography. 2.2 XP-SWMM ANALYSIS & RESULTS Based on Lake County 1-foot contour topographic mapping data, the study area watershed consists of approximately 278 acres located within the Village and unincorporated Lake County. The watershed boundary extends from Green Bay Road on the west to Sheridan Road on the east between Tangley Oaks Subdivision and the Great Lakes Naval Base (Naval Base) as shown on Exhibit 1. Drainage is generally from west to east towards the existing culverts under the Union Pacific Railroad (UPRR) and Sheridan Road. Subbasin boundaries were delineated using Lake County 1-foot contour aerial topographic data, site specific survey data, sewer information from the as-built plans, and field observation. The subbasin boundaries are shown on Exhibit 1. Existing storm sewer information for the Campbell Court study area is shown on Exhibit 2. Hydrologic parameters including Runoff Curve Number (RCN) and Time of Concentration (Tc) were calculated for each subbasin based on existing land use determined from aerial photography. Rainfall data was taken from the Lake Bluff Public Works Precipitation Gage for the May 12, 2014 storm event. An existing conditions hydrologic and hydraulic model was developed using XP-SWMM software. The XP-SWMM software is a dynamic modeling program that calculates the hydrologic response (Runoff Mode) from a storm event and routes the runoff through a storm sewer network and overland drainage system (Hydraulics Mode). The XP-SWMM software was chosen for this analysis as it is able to simulate surcharged storm sewer systems overland flow and surface storage using the St. Venant equations for unsteady flow. This software was originally developed by the U.S. Environmental Protection Agency (USEPA) for analyzing urban flooding and is widely used locally and nationally in this capacity. 3

30 Campbell Court Drainage Investigation March 2015 The XP-SWMM model was calibrated to known May 2014 storm event High Water Marks (HWM) in the Campbell Court rear yards as indicated by the residents. The Antecedent Moisture Condition (AMC) was set to 3 for the calibration run due to 0.4 inches of rainfall on May 11, 2014 that saturated the ground. Additionally, the Village indicated that the 36-inch diameter culvert outlet under the UPRR tracks was partially blocked by a fallen tree during the May 2014 storm event. Both items were taken into consideration for the model calibration. The model was also run for the 10-, 25-, 50-, and 100-year design storm events. A critical duration analysis was performed to determine the critical peak elevations for Campbell Court rear yards using Lake County rainfall data and Huff rainfall distributions. The results of the critical duration analysis show that the 18-hour design storm event is the critical duration event for the study area. The model results agreed well with the peak flowrates from the 2007 Fluid Clarity study for Arden Shores. A summary of the existing conditions XP-SWMM results at selected locations is provided in Table 2-1 below. Storm Event May yr 50-yr 25-yr 10-yr 36" Sheridan Rd Culvert Flow (cfs) Overflow from Arden Shore Estates toward Campbell Ct (cfs) Low Entry Elevation (ft) Known HWM (ft) ±663.4 N/A XP-SWMM Peak Elevation at Campbell Ct Rear Yards (ft) Table 2-1 Existing Conditions XP-SWMM Results 2.3 OBSERVATIONS Observations from the existing conditions analysis are provided in this section. Based on aerial photography and Lake County topographic data, there is little stormwater storage available within the watershed to attenuate peak runoff rates. The Tangley Oaks Subdivision has several detention basins to store stormwater. However, the portion of the watershed within unincorporated Lake County does not have significant stormwater storage volume. This is confirmed in the 2007 Fluid Clarity report for Arden Shores. CBBEL survey shows that stormwater runoff ponds behind the 36-inch diameter UPRR culvert crossing and is able to overflow into the Naval Base detention basin at elevation feet for storm events greater than the 10-year recurrence interval. Review of Lake County 1-foot contour aerial topography indicates that the UPRR ditch overflow into the adjacent detention basin is approximately 1.4 feet lower than it was prior to construction of the detention basin. Additionally, the existing overflow into the detention basin is 4

31 Campbell Court Drainage Investigation March 2015 approximately 0.8 feet below the low entry elevation of the lowest house on Campbell Court. The results of the XP-SWMM modeling show that stormwater runoff surcharges the existing 18-inch diameter storm sewer immediately south of the Naval Base and flows overland from Arden Shore Estates towards Campbell Court for the 10-year storm event. Based on CBBEL survey data and detailed XP-SWMM modeling, Campbell Court structures have a 50-year level of flood protection. 5

32 Campbell Court Drainage Investigation March 2015 CHAPTER ALTERNATIVE 1A PROPOSED CONDITIONS Alternative 1A consists of constructing approximately 4.0 acre-ft of flood storage volume in two storage basins on the north and south sides of Melvin Drive in Arden Shore Estates. For larger storm events, stormwater runoff will be diverted to the new flood storage from the overland channel immediately north of the Melvin Drive/Douglas Terrace intersection. Low flow will continue to be conveyed by the overland channel to the existing 18-inch diameter storm sewer during smaller storm events. A schematic of the concept level improvements is provided as Exhibit 3. Alternative 1A will require acquisition of eight parcels. Significant clearing of trees and brush will be required. The Village has indicated that existing roads in this area likely will not be able to withstand the heavy truck traffic required to complete excavation of the new flood storage basins. Reconstruction of roadways from the proposed storage basins to Green Bay Road will be required. This alternative will require a Watershed Development Permit (WDP) from Lake County that may include wetland permitting through the U.S. Army Corps of Engineers (USACE). Coordination with private property owners will also be required. CBBEL updated the existing conditions XP-SWMM model to reflect the concept level improvements and ran the model for the 10-, 25-, 50-, and 100-year design storm events. A comparison of the proposed conditions XP-SWMM results to existing conditions is provided in Table 3-1 below. The engineer s estimate of probable cost for concept level Alternative 1A improvements is $2,479,700. Cost estimates are included in Appendix yr 50-yr Existing Proposed Difference Existing Proposed Difference 36" Sheridan Rd Culvert Flow (cfs) Overflow from Arden Shore Estates toward Campbell Ct (cfs) XP-SWMM Peak Elevation at Campbell Ct Rear Yards (ft) yr 10-yr Existing Proposed Difference Existing Proposed Difference 36" Sheridan Rd Culvert Flow (cfs) Overflow from Arden Shore Estates toward Campbell Ct (cfs) XP-SWMM Peak Elevation at Campbell Ct Rear Yards (ft) Table 3-1 Alternative 1A XP-SWMM Results 6

33 Campbell Court Drainage Investigation March 2015 The results of the XP-SWMM modeling show the following: The peak WSEL at the Campbell Court rear yards is minimally reduced for the 25-, 50-, and 100-year storm events. This is due to overflow from the UPRR ditch to the Naval Base detention basin at elevation feet. The 10-year storm peak WSEL is reduced by 0.5 feet. Once the peak WSEL falls below the overflow elevation to the Naval Base detention basin, the effect of upstream storage volume within the watershed is more pronounced. Peak overflow rates toward Campbell Court from areas within unincorporated Lake County are significantly reduced for all analyzed storm events. Peak flowrates to the existing 36-inch diameter Sheridan Road culvert crossing are not appreciably reduced due to overflow from the UPRR ditch to the Naval Base detention basin. Therefore, it is not possible to install an additional outlet pipe under the UPRR and Sheridan Road from the study area without causing increases in flowrates and velocities of floodwater during storm events. 7

34 Campbell Court Drainage Investigation March ALTERNATIVE 1B Alternative 1B consists of constructing approximately 6.3 acre-ft of flood storage volume in three storage basins on the north and south sides of Melvin Drive and west of Douglas Terrace. For larger storm events, stormwater runoff will be diverted to the new flood storage from the overland channel immediately north of the Melvin Drive/Douglas Terrace intersection. Low flow will continue to be conveyed by the overland channel to the existing 18-inch diameter storm sewer during smaller storm events. A schematic of the concept level improvements is provided as Exhibit 4. Alternative 1B will require acquisition of eleven parcels. Significant clearing of trees and brush will be required. The Village has indicated that existing roads in this area likely will not be able to withstand the heavy truck traffic required to complete excavation of the new flood storage basins. Reconstruction of roadways from the proposed storage basins to Green Bay Road will be required. This alternative will require a WDP from Lake County that may include permitting through USACE. Coordination with private property owners will also be required. CBBEL updated the existing conditions XP-SWMM model to reflect the concept level improvements and ran the model for the 10-, 25-, 50-, and 100-year design storm events. A comparison of the proposed conditions XP-SWMM results to existing conditions is provided in Table 3-2 below. The engineer s estimate of probable cost for concept level Alternative 1B improvements is $3,356,700. Cost estimates are included in Appendix yr 50-yr Existing Proposed Difference Existing Proposed Difference 36" Sheridan Rd Culvert Flow (cfs) Overflow from Arden Shore Estates toward Campbell Ct (cfs) XP-SWMM Peak Elevation at Campbell Ct Rear Yards (ft) yr 10-yr Existing Proposed Difference Existing Proposed Difference 36" Sheridan Rd Culvert Flow (cfs) Overflow from Arden Shore Estates toward Campbell Ct (cfs) XP-SWMM Peak Elevation at Campbell Ct Rear Yards (ft) Table 3-2 Alternative 1B XP-SWMM Results 8

35 Campbell Court Drainage Investigation March 2015 The results of the XP-SWMM modeling show the following: The peak WSEL at the Campbell Court rear yards is minimally reduced for the 25-, 50- and 100-year storm events. This is due to overflow from the UPRR ditch to the Naval Base detention basin at elevation feet. The 10-year storm event peak WSEL is reduced by 0.85 feet. Once the peak WSEL falls below the overflow elevation to the Naval Base detention basin, the effect of upstream storage volume within the watershed is more pronounced. Peak overflow rates toward Campbell Court from areas within unincorporated Lake County are significantly reduced for all analyzed storm events. Peak flowrates to the existing 36-inch diameter Sheridan Road culvert crossing are not appreciably reduced due to overflow from the UPRR ditch to the Naval Base detention basin. Therefore, it is not possible to install an additional outlet pipe under the UPRR and Sheridan Road from the study area without causing increases in flowrates and velocities of floodwater during storm events. 9

36 Campbell Court Drainage Investigation March ALTERNATIVE 2 Alternative 2 consists of analyzing the benefits to Campbell Court by implementing Option 1 from the 2007 Fluid Clarity report. A diversion channel is proposed from the existing 30-inch diameter culvert under the EJ&E railroad tracks to the open space wetland area north of Juneway Terrace. The diversion re-directs all runoff from the 25 acre Subbasin 207 and eliminates flow through the 30-inch diameter culvert. All of the runoff from this area would be diverted away from the Campbell Court area. Approximately 7.1 acre-ft of new flood storage is proposed to mitigate peak flowrates from the diversion channel. A schematic of the concept level improvements is provided as Exhibit 5. Alternative 2 will require significant clearing of trees and brush. The open space north of Juneway Terrace likely contains wetland areas with specific permitting and construction requirements that may complicate the completion of this alternative. The Village has indicated that existing roads in this area likely will not be able to withstand the heavy truck traffic required to complete excavation of the new flood storage. Reconstruction of roadways from the proposed storage to Green Bay Road will be required. This alternative will require a WDP from Lake County that may include permitting through USACE. Coordination with private property owners on Bayshore Drive and with the EJ&E railroad will also be required. CBBEL updated the existing conditions XP-SWMM model to reflect the concept level improvements and ran the model for the 10-, 25-, 50-, and 100-year design storm events. A comparison of the proposed conditions XP-SWMM results to existing conditions is provided in Table 3-3 below. The engineer s estimate of probable cost for concept level Alternative 2 improvements is $2,400,800. Cost estimates are included in Appendix yr 50-yr Existing Proposed Difference Existing Proposed Difference 36" Sheridan Rd Culvert Flow (cfs) Overflow from Arden Shore Estates toward Campbell Ct (cfs) XP-SWMM Peak Elevation at Campbell Ct Rear Yards (ft) yr 10-yr Existing Proposed Difference Existing Proposed Difference 36" Sheridan Rd Culvert Flow (cfs) Overflow from Arden Shore Estates toward Campbell Ct (cfs) XP-SWMM Peak Elevation at Campbell Ct Rear Yards (ft) Table 3-3 Alternative 2 XP-SWMM Results 10

37 Campbell Court Drainage Investigation March 2015 The results of the XP-SWMM modeling show the following: The peak WSEL at the Campbell Court rear yards is reduced by about 0.1 feet for the 25-, 50-, and 100-year storm events. This is due to overflow from the UPRR ditch to the Naval Base detention basin at elevation feet. The 10-year storm peak WSEL is reduced by 0.61 feet. Once the peak WSEL falls below the overflow elevation to the Naval Base detention basin, the effect of upstream storage volume within the watershed is more pronounced. Peak overflow rates toward Campbell Court from areas within unincorporated Lake County are reduced for all analyzed storm events. Peak flowrates to the existing 36-inch diameter Sheridan Road culvert crossing are not appreciably reduced due to overflow from the UPRR ditch to the Naval Base detention basin. Therefore, it is not possible to install an additional outlet pipe under the UPRR and Sheridan Road from the study area without causing increases in flowrates and velocities of floodwater during storm events. 11

38 Campbell Court Drainage Investigation March ALTERNATIVE 3 Alternative 3 proposes to excavate the existing berm behind Campbell Court residences within the Lake County Division of Transportation (LCDOT) Right-of-Way (ROW) and use a portion of the excavated material to fill low areas in rear yards of 1005, 1009, 1013, 1017, and 1021 Campbell Court. The remaining excavated material will be distributed within the LCDOT ROW south of the excavation. The project results in a net increase of approximately 3.9 acre-ft in stormwater storage volume below the peak 100-year WSEL. An approximately 10-foot wide shelf is proposed to be graded along the existing distribution pole alignment to maintain access to the structures. A small concrete retaining wall is proposed behind the residence at 1017 Campbell Court with a small pump to evacuate any runoff that may collect behind the wall. Overland flow from the northwest of Campbell Court will be directed to the UPRR ditch through a new swale on Naval Base property. A schematic of the concept level improvements is provided as Exhibit 6. Alternative 3 will require significant clearing of trees and brush and coordination with multiple property owners for work on private property. Easements from each property owner will be required and significant coordination would be required for this alternative. This alternative will require a WDP from Lake County that may include permitting through USACE. Reconstruction of roadways will not be required as all material is proposed to be re-used onsite. Based on preliminary discussions with the LCDOT, they were agreeable to using their property for flood storage improvements. CBBEL updated the existing conditions XP-SWMM model to reflect the concept level improvements and ran the model for the 10-, 25-, 50-, and 100-year design storm events. A comparison of the proposed conditions XP-SWMM results to existing conditions is provided in Table 3-4 below. The engineer s estimate of probable cost for concept level Alternative 3 improvements is $1,003,500. Cost estimates are included in Appendix yr 50-yr Existing Proposed Difference Existing Proposed Difference 36" Sheridan Rd Culvert Flow (cfs) Overflow from Arden Shore Estates toward Campbell Ct (cfs) XP-SWMM Peak Elevation at Campbell Ct Rear Yards (ft) yr 10-yr Existing Proposed Difference Existing Proposed Difference 36" Sheridan Rd Culvert Flow (cfs) Overflow from Arden Shore Estates toward Campbell Ct (cfs) XP-SWMM Peak Elevation at Campbell Ct Rear Yards (ft) Table 3-4 Alternative 3 XP-SWMM Results 12

39 Campbell Court Drainage Investigation March 2015 The results of the XP-SWMM modeling show the following: The peak WSEL at the Campbell Court rear yards is not significantly reduced for the 10-, 25-, 50-, and 100-year storm events. This is due to overflow from the UPRR ditch to the Naval Base detention basin at elevation feet. Peak overflow rates toward Campbell Court from areas in unincorporated Lake County are not reduced for all analyzed storm events. Stormwater is directed to the UPRR ditch through a new swale. Alternative 3 provides a benefit to Campbell Court homeowners by creating a larger usable backyard space that is inundated by floodwaters less frequently than under existing conditions. The area of frequent flooding would be shifted further east within the LCDOT ROW adjacent to the UPRR property and away from residences. Peak flowrates to the existing 36-inch diameter Sheridan Road culvert crossing are not appreciably reduced due to overflow from the UPRR ditch to the Naval Base detention basin. Therefore, it is not possible to install an additional outlet pipe under the UPRR and Sheridan Road from the study area without causing increases in flowrates and velocities of floodwater during storm events. While this alternative will not significantly reduce flood elevations in the study area, it will raise the rear yards of the housed along the east side of Campbell Court above the 100- year flood elevation. The excavation within the LCDOT ROW would provide a surplus of compensatory storage for this fill. While not specifically included as part of the alternative, the rear yards along the west side of Campbell Court could also be filled, but this would require removal of large mature trees. 13

40 Campbell Court Drainage Investigation March ALTERNATIVE 4 Alternative 4 proposes to excavate approximately 2.5 acre-ft of flood storage volume in the Tangley Oaks Subdivision located immediately south of the Village s sanitary lift station. The cut material will be distributed within the LCDOT ROW east of the excavation. A schematic of the concept level improvements is provided as Exhibit 7. Alternative 4 will require significant clearing of trees and brush. Reconstruction of roadways will not be required. Based on preliminary discussions with the LCDOT, they were agreeable to using their property for flood storage improvements. This alternative will require a WDP from Lake County that may include permitting through USACE. Coordination with the Tangley Oaks homeowner s association will also be required. CBBEL updated the existing conditions XP-SWMM model to reflect the concept level improvements and ran the model for the 10-, 25-, 50-, and 100-year design storm events. A comparison of the proposed conditions XP-SWMM results to existing conditions is provided in Table 3-5 below. The engineer s estimate of probable cost for concept level Alternative 4 improvements is $1,235,700. Cost estimates are included in Appendix yr 50-yr Existing Proposed Difference Existing Proposed Difference 36" Sheridan Rd Culvert Flow (cfs) Overflow from Arden Shore Estates toward Campbell Ct (cfs) XP-SWMM Peak Elevation at Campbell Ct Rear Yards (ft) yr 10-yr Existing Proposed Difference Existing Proposed Difference 36" Sheridan Rd Culvert Flow (cfs) Overflow from Arden Shore Estates toward Campbell Ct (cfs) XP-SWMM Peak Elevation at Campbell Ct Rear Yards (ft) Table 3-5 Alternative 4 XP-SWMM Results 14

41 Campbell Court Drainage Investigation March 2015 The results of the XP-SWMM modeling show the following: The peak WSEL at the Campbell Court rear yards is minimally reduced for the 25-, 50-, and 100-year storm events. This is due to overflow from the UPRR ditch to the Naval Base detention basin at elevation feet. The 10-year storm peak WSEL is reduced by 0.5 feet. Once the peak WSEL falls below the overflow elevation to the Naval Base detention basin, the effect of upstream storage volume within the watershed is more pronounced. Peak overflow rates toward Campbell Court from areas in unincorporated Lake County are not reduced. Peak flowrates to the existing 36-inch diameter Sheridan Road culvert crossing are not appreciably reduced due to overflow from the UPRR ditch to the Naval Base detention basin. Therefore, it is not possible to install an additional outlet pipe under the UPRR and Sheridan Road from the study area without causing increases in flowrates and velocities of floodwater during storm events. 15

42 Campbell Court Drainage Investigation March 2015 CHAPTER 4 CONCLUSIONS The improvement alternatives discussed in Chapter 3 will benefit Campbell Court residences. Flood storage in the upstream watershed significantly lowers peak WSEL for the 10-year design storm event. However, the volume of stormwater storage that can be provided within the available open space areas does not significantly lower peak WSEL for larger storm events. CBBEL calculations show that approximately 23 acre-ft of upstream stormwater storage volume would be required to lower the peak 100-year WSEL by 1-foot in the Campbell Court rear yards. A summary of the engineer s estimates of probable cost is provided in Table 4-1 below. Alternative 1A Alternative 1B Alternative 2 Alternative 3 Alternative 4 Engineer's Estimate of Probable Cost $2,479,700 $3,356,700 $2,400,800 $1,003,500 $1,235,700 Table 4-1 Engineer s Estimate of Probable Cost Regardless of whether or not one of the drainage improvement project are constructed, each property owner that experienced flooding in the past should evaluate their property and implement flood proofing measures as necessary to reduce the risk of future flooding. CBBEL also recommends that any development upstream of the study area be required to provide stormwater detention as there is inadequate downstream capacity within the study area to accommodate additional runoff. Additionally, it is recommended that that Union Pacific Railroad (UPRR) ditch through the study area be cleaned on a regular basis to improve flow and lessen that chance of culvert blockage. The culverts under the UPRR and Sheridan Road should also be televised to verify their condition. The results of this study should be used as the basis for further detailed analysis and design of the preferred improvement alternative. Upon selection of a preferred alternative(s), it is recommended that additional data collection such as detailed topographic survey and wetland delineation be completed in additional to meeting with regulatory agencies, stakeholders, and residents. All projects will require a WDP which may be issued by Lake County or the Village depending on the selected alternatives. It is recommended that the results of this study be discussed with Lake County to discuss permitting requirements and funding opportunities. N:\LakeBluff\ Campbell\Water\Docs\R.Campbell Ct docx 16

43 UNNAMED BRIERFIELD CT OHIO ST MAINE AVE N ST I Feet 1 inch = 450 feet ILLINOIS ST 6TH AVE IL ROUTE 131 UNNAMED N ADMIRAL DR ILLINOIS ST 4TH AVE Union-Pacific Railroad EJ&E Railroad FORRESTAL DR Great Lakes Naval Base S ADMIRAL DR SPRING LN SHERIDAN RD MERIDIAN DR HAWAII AVE GREEN BAY RD BAYSHORE DR HILLSIDE AVE 207 GLENDELL AVE 206 FOREST VIEW DR RIVERS DR ST AVE ARKANSAS AVE ALABAMA AVE ATLANTIC RD IL ROUTE NORWICH CT MARGATE CT 806 W KOHL AVE 260 W MELVIN DR CAMPBELL CT 217 ARBOR DR SIGNE CT OAK RIDGE CT 210 BELLE FORET DR WARRINGTON DR 200 JAMES CT JAMES CT PHILIP CT 202 HEATHROW CT Tangley Oaks Subdivision HAMILTON CT GREENWICH CT THORNVALLEY RD ROTHBURY CT GRAFTON CT CRABTREE LN WINCHESTER CT ARMOUR DR COVENTRY CT ASCOT CT CARLYLE CIR Legend WEATHERFORD CT Existing Storm Sewer BUCKMINSTER CT Subbasin Boundary Unincorporated Lake County B C B Christopher B. Burke Engineering, Ltd West Higgins Road, Suite 600 Rosemont, IL (847) / FAX (847) CLIENT TITLE VILLAGE OF LAKE BLUFF LOCATION MAP PROJECT NO DSGN. DEV DATE CHKD.. 03/03/15 EXHIBIT 1

44 30" CAMPBELL CT OHIO ST 36" I Feet 1 inch = 150 feet j 36" 15" j 15" 36" Great Lakes Naval Base j ILLINOIS ST j 1ST AVE 18" j j SHERIDAN RD SHORE ACRES DR ARDEN SHORE DR " W MELVIN DR " 36" DOUGLAS TRCE j j " W KOHL AVE 15" 24" 30" 1005 j j LANCASTER CT Tangley Oaks Subdivision j 2-18" 24" ARBOR DR Legend ARMOUR DR j Existing Storm Sewer 10-Year Inundation 100-Year Inundation Parcel Bondary Flow Direction Unincorporated Lake County INVERNESS CT Union-Pacific Railroad B C B Christopher B. Burke Engineering, Ltd West Higgins Road, Suite 600 Rosemont, IL (847) / FAX (847) CLIENT TITLE VILLAGE OF LAKE BLUFF EXISTING CONDITIONS PROJECT NO DSGN. DEV DATE CHKD.. 03/03/15 EXHIBIT 2

45 " 18" I inch = 100 feet Feet ILLINOIS ST 1ST AVE " Flood Storage #1 +/- 1 ac-ft " W MELVIN DR 30" Flood Storage #2 +/- 3 ac-ft Legend Existing Storm Sewer Proposed Storm Sewer 683 Proposed Grading Parcel Boundary DOUGLAS TRCE W KOHL AVE " " 24" 662 N:\LakeBluff\ Campbell\GIS\Exhibits\EXH 3_Alternative 1A.mxd C B Christopher B. Burke Engineering, Ltd West Higgins Road, Suite 600 Rosemont, IL B(847) / FAX (847) CLIENT TITLE VILLAGE OF LAKE BLUFF DSGN. DEV JOB# ALTERNATIVE 1A SCHEMATIC CHKD. DATE 03/03/15 EXHIBIT 3

46 " 18" I inch = 100 feet Feet ILLINOIS ST 1ST AVE " Flood Storage #1 +/- 1 ac-ft " 24" W MELVIN DR 30" Flood Storage #3 +/- 2.3 ac-ft 12" Flood Storage #2 +/- 3 ac-ft DOUGLAS TRCE " Legend Existing Storm Sewer Proposed Storm Sewer W KOHL AVE " 664 Proposed Grading Parcel Boundary N:\LakeBluff\ Campbell\GIS\Exhibits\EXH 4_Alternative 1B.mxd C B Christopher B. Burke Engineering, Ltd West Higgins Road, Suite 600 Rosemont, IL B(847) / FAX (847) CLIENT TITLE VILLAGE OF LAKE BLUFF DSGN. DEV JOB# ALTERNATIVE 1B SCHEMATIC CHKD. DATE 03/03/15 EXHIBIT 4

47 UNNAMED I inch = 100 feet Feet JUNEWAY TER Subbasin 207 = 25 Acres SPRING LN BAYSHORE DR " Diversion Channel j Create 7.1 ac-ft of storage volume j j " FOREST VIEW DR Legend Existing Storm Sewer Existing Subbasin Boundary Proposed Grading B C B Christopher B. Burke Engineering, Ltd West Higgins Road, Suite 600 Rosemont, IL (847) / FAX (847) CLIENT TITLE VILLAGE OF LAKE BLUFF ALTERNATIVE 2 SCHEMATIC PROJECT NO DSGN. DEV DATE CHKD.. 03/03/15 EXHIBIT 5

48 30" CAMPBELL CT I inch = 60 feet Feet ST AVE Construct Overland Flow Swale OHIO ST j j 18" 660 j j " W MELVIN DR " 36" Pump Behind Wall " W KOHL AVE 24" 30" 15" Legend Existing Storm Sewer Existing Distribution Pole Access Path Proposed Grading Wetland (EL ft) Concrete Wall (EL 644 ft) Parcel Boundary Proposed Swale j 10 ft Wide Access Path for Dist Pole Access B C B Christopher B. Burke Engineering, Ltd West Higgins Road, Suite 600 Rosemont, IL (847) / FAX (847) CLIENT TITLE VILLAGE OF LAKE BLUFF ALTERNATIVE 3 SCHEMATIC PROJECT NO DSGN. DEV DATE CHKD.. 03/03/15 EXHIBIT 6

49 30" I inch = 100 feet Feet " W KOHL AVE 15" " CAMPBELL CT 30" Flood Storage #4 +/- 2.5 ac-ft " " Legend 672 Existing Storm Sewer Proposed Grading Parcel Boundary N:\LakeBluff\ Campbell\GIS\Exhibits\EXH 7_Alternative 4.mxd C B Christopher B. Burke Engineering, Ltd West Higgins Road, Suite 600 Rosemont, IL B(847) / FAX (847) CLIENT TITLE VILLAGE OF LAKE BLUFF DSGN. DEV JOB# ALTERNATIVE 4 SCHEMATIC CHKD. DATE 03/03/15 EXHIBIT 7