THE VILLAGE OF LOMBARD TERRACE VIEW POND STORMWATER IMPROVEMENTS FEASIBILITY STUDY

Transcription

1 THE VILLAGE OF LOMBARD TERRACE VIEW POND STORMWATER IMPROVEMENTS FEASIBILITY STUDY Prepared by: Christopher B. Burke Engineering, Ltd W. Higgins Road, Suite 600 Rosemont, IL Date: October 6, 2011

2 TERRACE VIEW POND IMPROVEMENTS Village of Lombard PROJECT DEVELOPMENT REPORT This report examines options for increasing stormwater storage /storm sewer capacity on the site to potentially reduce flooding in the adjoining neighborhoods. It is important that this goal be achievable while considering the aesthetic and recreational aspects of pond and adjoining open space. The report evaluates the capacity of the existing storm sewer network upstream of the pond in the neighborhood that currently experiences flooding as well as the downstream sewer system that drains the pond. It is important to determine that any proposed pond or storm sewer improvements will not adversely affect upstream or downstream areas. Several different options will be explored for achieving increased stormwater storage or increasing storm sewer capacity within the Terrace View Pond site. Each of the options will be defined and the implications of implementing each of the options will be discussed. 1 Village of Lombard

3 REPORT OUTLINE I. Description of Project Site II. III. IV. History of Site Existing Conditions a. Stormwater infrastructure b. Wetland shoreline Options a. Option A - Lower water level +/- 1' with new pump station and vegetate newly exposed mudflat habitat b. Option B - Excavate the area to the southeast and create a detention facility adjoining the pond. c. Option C - Lower water level +/- 1' with new gravity sewer and re-grade / re-vegetate banks d. Option D - Lower water level +/- 1' with new pump station, re-grade / re-vegetate banks and dredge pond in order to maintain or increase depth of water e. Option E Remove all normal water and create a wetland bottom detention facility f. Option F - Install relief sewers from Crystal Avenue into Terrace View Pond without lowering the normal water level of the pond. g. Lower water level ± 1 and install relief sewers from Crystal Avenue into pond V. Hydraulic Analysis VI. VII. VIII. Option Comparison Matrix Recommendation Appendix a. Wetland report b. Minutes of Meeting with DuPage County EDP Division of Environmental Concerns c. EcoCAT Review/IDNR Letter d. Summary of Hydraulic Analysis e. Historic Terrace View Documents 2 Village of Lombard

4 I. DESCRIPTION OF PROJECT SITE Terrace View Pond is located in the northwest corner of the Village of Lombard. The site is bounded to the north by Crystal Avenue, the east by Park Avenue, the south by Greenfield Avenue and the west by Elizabeth Street and is just east of Terrace View School. The pond drains through the Village s gravity sewer system to the Route 53 Pump Station and ultimately to the East Branch of the DuPage River. The pond is used primarily for recreational purposes but also provides important stormwater storage for the surrounding areas, which have experienced repeated flooding events. Terrace View Pond has a direct tributary area of over 240 acres. Additionally, Broadway Slough located to the northwest is conveyed to Terrace View Pond via storm sewer. The other areas north of the Great Western Trail are also tributary to Terrace View Pond via overland flow for a total tributary area of approximately 425 acres, as shown on the figure below. BROADVIEW SLOUGH DRAINAGE AREA LIMIT TERRACE VIEW POND OUTLET SEWER N. Elizabeth St. Greenfield Ave. GREAT WESTERN TRAIL Drainage Area 3 Village of Lombard

5 II. HISTORY OF THE SITE Since there are a multitude of elements that influence the nature of the site, it is worthwhile to look at the history of the site. Frequently stormwater features are manmade creations built at the time of the adjoining development. As illustrated in the following aerial photos, the site that we now know as Terrace View Pond was once a naturally occurring wetland. There is no evidence that it ever had an open water area prior to the 1970 s. It appears that it was a naturally occurring depression that local farmers tiled and attempted to farm. You can see evidence of the wetlands in the irregular shaped clusters of vegetation along the edges of the farm fields. N. Elizabeth St. Farmed Wetland Future site of Terrace View School Greenfield Avenue 1939 Aerial Photo of Project Site 4 Village of Lombard

6 N. Elizabeth St. Terrace View School Wetland Greenfield Avenue 1961 Aerial Photo of Project Site Then in the 1950 s and 1960 s the surrounding neighborhoods were beginning to be developed. In the 1961 aerial photo the farming had stopped and area was reverting to its natural vegetated wetland state. 5 Village of Lombard

7 N. Elizabeth St. Terrace View School Terrace View Pond Pump Station Greenfield Avenue 1974 Aerial Photo of Project Site By 1974 the pond had been constructed. Note the perimeter trail had not been constructed yet. Between 1972 and 1977 the Village and the Park District discussed the use of the site as a stormwater facility while maintaining passive recreation opportunities. Copies of these documents are included under Appendix E. Initially, when storm events occurred or pond maintenance was required, the ponds water elevation was lowered by a pump station located at the southwest corner of the pond. Unfortunately, it is not known if the pond was designed for a specific amount of stormwater storage. 6 Village of Lombard

8 Former Pump Station at Outlet Sewer The pump station structure still exists but the pump and its electrical service have been removed. Currently the concrete pump station box acts as a control structure. It has a weir that controls the amount of water flowing from the pond into the outlet sewer. Once the water in the pond exceeds the weir elevation, discharge from the pond is controlled by the capacity of the downstream sewer system. N. Elizabeth St. Terrace View School Terrace View Pond Pond Excavation Spoil Pile Greenfield Avenue 1988 Aerial Photo of Project Site 7 Village of Lombard

9 By 1988 the perimeter trail had been installed along with some of the shoreline trees. The adjoining shorelines appear to be turf and mowed to the water s edge. A large spoil pile from pond excavation was deposited to the south of the pond. 8 Village of Lombard

10 III. EXISTING CONDITIONS At the time of the project survey (July 2011), the pond water surface area covered +/-12.8 acres giving it a shoreline of approximately 4,227 linear feet. Native plants have been planted along the entire perimeter of the shoreline. The excavated spoil pile that was created in the 1970 s has been removed and that area has been graded out to be used as a passive recreation area. The pond receives surface runoff from the surrounding open space and from various storm sewers systems. There is a 36 sewer and a 27 sewer with a 12 overflow outlet that drain Crystal Avenue; a 12 culvert under the path at the north end of the pond and a 30 sewer that drains Park Avenue/Brown Street. A 36 sewer brings in stormwater from the areas to the west. There is also a swale that drains the green area southeast of the pond. The storm sewer systems and swale that drain into the pond, are identified below. 27 RCP 12 RCP 12 RCP 36 RCP 30 RCP 36 RCP SWALE Indicates piped supply Indicates overland flow RCP = Reinforced Concrete Pipe Supply of stormwater to the pond Terrace View Pond is part of a historic drainage way that has always been naturally tributary to the east branch DuPage River. The pond itself is within the regulatory floodplain. The DuPage Regulatory Flood Map (RFM) is shown below. 9 Village of Lombard

11 Regulatory Flood Map of the Terrace View Pond Area 10 Village of Lombard

12 Photo taken at outfall structure (former pump station) looking east Mature trees and native forbs grow to the edge of the shoreline in some places. Photo taken along south shoreline looking northeast Lily pads dominate the shallow southern shoreline. 11 Village of Lombard

13 Photo taken on east shoreline looking west This view illustrates the open water of the south portion of the pond. Photo taken on east shoreline looking south Native grasses dominate the sunny western facing banks. 12 Village of Lombard

14 South Outfall Structure Outfall Structure Existing Path Water leaves pond at Gravity line Water enters Greenfield Avenue system Detail of South Outfall Structure 13 Village of Lombard

15 Wetland Shoreline Portions the pond fringe and pond are considered to be wetland; additionally a swale that drains to the Pond was also identified as wetland. Terrace View Pond has a planted wetland perimeter consisting of wet prairie and prairie vegetation. Additionally, the pond contains white water lily, duckweed and algae. The prairie and wet prairie established vegetation is a fairly diverse and is dominated by natives and received a high floristic rating. Existing Shoreline Cross Section CBBEL staff met on site with Mary Beth Falsey of DuPage County on July 26, 2011 who confirmed the wetland boundaries that were staked by CBBEL staff. According to the County, the pond/wetland area is considered a critical wetland based on the floristic inventory. CBBEL also met with County staff to discuss the pond s wetland qualities and how changes to the pond would impact the wetland habitat. Minutes from this meeting are attached in the appendix of this document. The result from the wetland delineation and meeting with the County is that the recognized wetland adjoining the pond has an impact and influence on any improvements considered. 14 Village of Lombard

16 IV. OPTIONS A variety of options for increasing the storage capacity of the pond or increasing storm sewer capacity into the pond have been developed and are described in this section of the report. A hydraulic analysis describing the benefits of each option is summarized in the following section. Option A Lower water level +/- 1' with new pump station and re-grade/re-vegetate banks As previously discussed, stormwater is stored above the pond s normal water level, therefore one way to increase the available volume of stormwater storage is to lower the normal water level. FLOOD LEVEL Existing Condition NORMAL WATER ELEVATION 15 Village of Lombard

17 FLOOD LEVEL Proposed Condition ADJUSTED NORMAL WATER The current water surface area is 12.8 acres. If the water level is lowered by 1 foot the new water surface area will be 12.6 acres. This will achieve approximately 12.8 ac ft of additional stormwater storage. 16 Village of Lombard

18 Detail #1 Detail #2 Detail #3 Pump Station Detail Detail #4 Surveyed Pond The following details illustrate the effect on the existing shoreline by lowering the pond level by 1 foot. Detail 1 illustrates that at that location approximately 6.5 feet of new shoreline will be created/exposed if the pond level is lowered by 1 foot. Detail 2 illustrates 3.6 feet of additional shoreline and details 4 and 5 each illustrate 2 feet of additional shoreline. The variation in the shoreline width is a result of the irregular depth of the pond along its perimeter edge. 17 Village of Lombard

19 Existing Bench Perimeter Path Identified Wetland Limits Existing Shoreline New Shoreline if water level is lowered by of new shoreline will be exposed. Detail #1 Asphalt Path from School Perimeter Path Identified Wetland Limits Existing Shoreline New Shoreline if water level is lowered by of new shoreline will be exposed. Detail #2 18 Village of Lombard

20 Perimeter Path Existing Bench Identified Wetland Limits Existing Shoreline New Shoreline if water level is lowered by 1. 2 of new shoreline will be exposed. Detail #3 New Shoreline if water level is lowered by 1. 2 of new shoreline will be exposed. Existing Shoreline Identified Wetland Limits Existing Sign Perimeter Path Detail #4 19 Village of Lombard

21 New Inlet POND New Wet Well With Pump Station Existing Path Force Main Existing Outlet Structure Check Valve Existing Gravity Pipe Water enters Greenfield Avenue system at Detail of Pump Station A Simplex pump station is proposed that will lower the pond water level approximately 1 foot. The proposed pump will be housed in a precast concrete wet well hydraulically connected to the pond via flared end section and reinforced concrete intake pipe. The pump will be sized at approximately 1,500 gpm to pump down the approximate 13 acre-ft volume within a 48 hour duration. The pump will be a submersible type similar to those currently in use at the Village s existing storm and sewage lift stations. Electric service will be obtained from the nearest available local utility pole with three phase power which appears to be on the west side of the pond along the rear yard of a residence. Electric service and pump controls will be housed in an above grade, stainless steel enclosure located adjacent to the proposed pump station wet well. The forcemain will be ductile iron pipe and will discharge into a proposed structure constructed on the existing 42 gravity outlet from the pond. 20 Village of Lombard

22 As illustrated in the following cross sections some of the exposed areas will be quite narrow. Park patrons may not sense much of a difference. The existing landscape could seamlessly blend into the exposed areas. Other areas will be a couple of yards wide. These wide areas could be treated with a conventional seed mix and plant plugs that are suitable for this type of situation. There are three options for the landscape restoration of this newly exposed shoreline. 1 st This is the simplest solution for the exposed shoreline restoration. A coir log will be staked in front of any exposed vertical shoreline. Coir fiber rolls are tightly bound rolls of coconut fiber that natural decompose over a 3-5 year period. This will have the least impact to the existing wetland. It will be visible the first season but will completely disappear from view as the newly installed plants establish. 2 nd In this solution, imported fill is placed in the area of the newly exposed shoreline. The fill material being placed within the flood plain, estimated to be approximately 280 cubic yards, would require 21 Village of Lombard

23 permitting efforts but would not require compensatory storage since it is below the current water level. Using a combination of erosion control fabric and plant plugs the placed material should be quickly stabilized. 3 rd In this option the entire bank slope is cut back in order to relax the previous sharp back cut. This solution actually increases the amount of flood plain storage but it disturbs large portions of the existing wetland vegetation. We recommend a combination of the 1 st and 2 nd shoreline treatment options. The more costly 1 st option using the coir fiber roll would be used along the far south and west pond edges where ponds fetch has caused a vertical slough. The 2 nd option would be used for the remainder of the shoreline. WETLAND PERMITTING Regardless of the solution for restoring the exposed shoreline, the lowering of the normal water level will have an effect on the fringe wetland as determined by DuPage County. The representatives with the County anticipate that existing vegetated fringe will shift downward to compensate to the lowering of the pond water level. This shifting will cause a loss in overall area of wetland plants. The extent of loss, if any, will be determined during an inspection of the site completed after 3 years after the project. This delineation will be compared to the original delineation and the difference calculated. The difference will be the basis for the area of mitigation required. Each of the previously mentioned solutions will have to be evaluated for their effect to the wetland. Once a solution is selected, CBBEL will then proceed with the appropriate permitting. The goal will be to have the least amount of impact on the wetland habitat and have the most increase for stormwater storage. 22 Village of Lombard

24 HYDRAULIC IMPACTS The hydraulic analysis included in the following section of the report details the benefits created by this scenario. There are no negative impacts throughout the system. The benefits to the flooding area on Crystal Avenue are quantified in Appendix E. COST ESTIMATE OPTION A Lower water level +/- 1' with new pump Station and regrade / revegetate banks UNIT TOTAL COSTS QTY. UNIT PRICE PRICE Pond Landscape Minor regrading of shoreline (no haul off) 1980 SY $20.00 $39, Coir fiber log (entire length of shoreline) 1255 LF $40.00 $50, Plant plugs (18" oc) 4486 EA $4.00 $17, Contractor access restoration 200 SY $1.50 $ Site Civil / MEP Erosion control 300 LF $4.00 $1, Construction entrance 1 LS $4, $4, Pump, guiderails & accessories 1 LS $20, $20, Simplex pump control panel 1 LS $70, $70, Electrical conduit & cable 1 LS $20, $20, Wet well, 6 ft. dia 1 LS $30, $30, Check valve 1 LS $5, $5, Wet well piping and valves 1 LS $8, $8, Inlet pipe, 24" RCP 50 FOOT $60.00 $3, Force main, 8" DIP 50 FOOT $50.00 $2, Discharge structure, 8 ft. dia 1 LS $10, $10, Electrical service 1 LS $10, $10, Contingency 20% $291, $58, CONSTRUCTION SUB TOTAL $350, Potential Wetland Impact Cost 0.3 AC $150, $45, PROFESSIONAL Design Engineering (8% of Construction Cost) $350, $28, Permitting (wetland hydrology and hydraulic analysis) (8%) $350, $28, Construction Engineering (10%) $350, $35, TOTAL $486, Village of Lombard

25 Option B Excavate the area to the southeast and create a detention facility adjoining the pond. The photo below illustrates that if the pond is expanded to the southeast approximately 8 acre feet of storage area will be achieved. Pipe Connection Approx. 8 ac ft Indicates location of detention facility Approx. 32,500 cubic yards of soil to be removed Approx. 25 trees to be removed Approx. 2.8 acres of wetland created 24 Village of Lombard

26 Typical cross section in the area of the pond expansion This option achieves 8 acre-feet of storage, although it is distributed throughout several vertical feet instead of at the bottom of the basin as in Option A. A portion of the existing wetland swale is disturbed as is a significant portion of the upland park site. This solution also places a wetland bottom detention basin close to the adjoining residents along West View Street. The detention facility would be excavated down to the elevation of the existing normal water level. It is possible that groundwater occurs naturally at this level and if the detention facility was made deeper it would fill in with ground water. If this were to occur it would affect the normal water elevation of the pond. WETLAND PERMITTING This option will likely have the least amount of impact on the adjoining existing wetland. The swale that currently drains into the pond would be disturbed but this would be compensated by the creation of the wetland bottom of the new detention facility. HYDRAULIC IMPACTS The hydraulic analysis included in the following section details the benefits created by this option. There are no negative impacts throughout the system. However, because this option does not lower the normal water level, it does not have the same benefits as Option A. The benefits from Option B are not significant and costs are relatively high. Therefore CBBEL does not recommend it. The flood elevations throughout the system are quantified in Appendix E. 25 Village of Lombard

27 COST ESTIMATE OPTION B Excavate the area to the southwest and create a detention facility adjoining the pond. UNIT TOTAL COSTS QTY. UNIT PRICE PRICE Tree removal 25 EA $ $12, Site Erosion Control Silt fence 2500 LF $3.00 $7, Construction access road 1 LS $4, $4, Earthwork Cut (haul off site) CY $30.00 $975, Pipe connection to pond 200 LF $50.00 $10, Landscape Walking path restoration 70 SY $20.00 $1, Site lawn restoration 2800 SY $10.00 $28, Basin bank seeding 4802 SY $3.00 $14, Bottom basin seeding SY $4.00 $55, Contingency 20% $1,108, $221, CONSTRUCTION SUB TOTAL $1,329, PROFESSIONAL Design Engineering (8% of Construction Cost) $1,329, $106, Permitting (wetland hydrology and hydraulic analysis) (8%) $1,329, $106, Construction Engineering (10%) $1,329, $132, TOTAL $1,675, Village of Lombard

28 Option C Lower water level +/- 1' with new gravity sewer and re-grade / re-vegetate banks Lower pond by 1 INV New Gravity Sewer 941lf INV This option would use a gravity sewer rather than a pump station to maintain the normal water level. The most direct route from the pond to the downstream system would connect at the intersection of Elizabeth Street and Windsor Avenue. The construction of this sewer would require acquisition of an easement from one or more property owners. This route would have approximately 2.5 of vertical drop over 941 linear feet of horizontal run, which is a slope of 0.27%. This indicates that the pipe would be relatively flat and may not be self cleaning due to the flat slope, which would likely require routine maintenance. Furthermore, there is a 48 water main running perpendicular to the route of 27 Village of Lombard

29 the proposed sewer which may pose a constructability issue if proper clearance cannot be achieved. Further investigation of the exact location of the water main will be necessary to complete the evaluation of this option. HYDRAULIC IMPACTS This scenario was not explicitly modeled but is hydraulically similar to Option A. COST ESTIMATE OPTION C Lower water level +/- 1' with new gravity sewer and re-grade / re-vegetate banks UNIT TOTAL COSTS QTY. UNIT PRICE PRICE Pond Landscape Minor regrading of shoreline (no haul off) 1980 SY $20.00 $39, Coir fiber log 1255 LF $40.00 $50, Plant plugs 4486 EA $4.00 $17, Contractor access restoration 200 SY $1.50 $ Site Civil Erosion control 300 LF $3.00 $ Construction entrance 1 LS $4, $4, Sewer pipe 941 LF $ $94, Control structure 1 EA $15, $15, Landscape Erosion control 1900 LF $3.00 $5, Pipe trench restoration 1255 SY $10.00 $12, Street patch 50 SY $ $5, Contingency 20% $245, $49, CONSTRUCTION SUB TOTAL $294, Potential Wetland Impact Cost 0.3 ACRE $150, $45, Easement Costs $75, PROFESSIONAL Surveying $5, Plats & Legals $5, Design Engineering (8% of Construction Cost) $294, $23, Permitting (wetland hydrology and hydraulic analysis) (8%) $294, $23, Construction Engineering (10%) $294, $29, TOTAL $500, Village of Lombard

30 Option D Lower water level +/- 1' with new pump station, re-grade / re-vegetate banks and dredge pond in order to create more open water 3 Acres 1 Acre Indicates areas to be dredged In this option the same 13 ac ft of storage is achieved as in option A. The other benefit of this solution is that current depths of the deep water portions of the pond are maintained for fish habitat. The current deeper areas are approximately 4 feet at the south and 5 feet at the north which provide marginal habitat to fish. The size and condition of the area for fish habitat is correlated to the species of fish. The size and the depth of the two deeper areas will only support smaller species of fish and scavenger fish. If only 1 foot depth of material is removed from the pond bottom (to compensate for lowering the water level) then 7,745 cubic yards of material will be removed. The above photo illustrates deepening of the pond in two locations. To achieve this, hydraulic dredging would be necessary. This process pulls material from the bottom of the pond without 29 Village of Lombard

31 completely draining the pond. A slurry of water and mud is pulled from the pond and pumped to an upland area. A portion of the park would have to be dedicated to the drying of the dredged material. The next issue is the permanent location of the dredged material. The material could be spread across the upland portion of the park or hauled off site. This may result in the temporary disruption the perimeter wetland edge. WETLAND PERMITTING This option would have the same shoreline restoration issues as Option A plus a portion of the bank edge would be disturbed during the dredging process for equipment access. This option would likely require significant wetland mitigation. HYDRAULIC IMPACTS This scenario was not explicitly modeled but is hydraulically identical to Option A. COST ESTIMATE OPTION D Lower water level +/- 1' with new pump station, re-grade / re-vegetate banks and dredge pond in order to maintain or increase depth of water UNIT TOTAL COSTS QTY. UNIT PRICE PRICE Pond Landscape Coir fiber log 4227 LF $40.00 $169, Plant plugs 4486 EA $4.00 $17, Contractor access restoration 200 SY $1.50 $ Site Civil / MEP Erosion control 300 LF $3.00 $ Construction entrance 1 LS $4, $4, Pump, guiderails & accessories 1 LS $20, $20, Simplex pump control panel 1 LS $70, $70, Electrical conduit & cable 1 LS $20, $20, Wet well, 6 ft. dia 1 LS $30, $30, Wet well piping and valves 1 LS $8, $8, Inlet pipe, 24" RCP 50 FOOT $60.00 $3, Force main, 8" DIP 50 FOOT $50.00 $2, Discharge structure, 8 ft. dia 1 LS $10, $10, Electrical service 1 LS $10, $10, Dredging Dredge operation 7745 CY $50.00 $387, Haul off * 7745 CY $40.00 $309, Landscape restoration 9200 SY $1.50 $13, Village of Lombard

32 Contingency 20% $1,076, $215, CONSTRUCTION SUB TOTAL $1,291, Potential Wetland Impact Cost 0.3 AC $150, $45, PROFESSIONAL Design Engineering (8% of Construction Cost) $1,291, $103, Permitting (wetland hydrology and hydraulic analysis) (8%) $1,291, $103, Construction Engineering (10%) 8% $1,291, $129, TOTAL $1,672, * Note: If the material was allowed to be spread on site this cost could be reduced to approximately $10/cy for a construction cost savings of approximately $230, Village of Lombard

33 Option E Remove all open water and create a wetland bottom detention facility WETLAND / NO OPEN WATER A section illustrating the drained pond 32 Village of Lombard

34 This option drains the water from the current pond and creates a wetland bottom detention facility. A full topography of the bottom of the pond is currently unavailable so the total volume of the pond that would be available for storage is unknown. CBBEL estimates that ac-ft of storage could be achieved. The pond would be drained by a proposed pump station. It is unclear as to how much of the current water in the facility is supplied from ground water sources so it is unknown if it is even possible to keep the facility dry. The historical air photos indicate that a wetland did exist here in the past without standing water however impervious surface that drain to areas have increased dramatically. Plus the pond was deepened at some point and it is possible that normal ground water would fill those areas in. Thus, we assume this option would consist of a combination of lowering the water level ± 2 feet and filling in the deeper areas to the new lower water level. WETLAND PERMITTING This solution would have a dramatic effect on the existing wetland fringe and it would remove the lily pad habitat that occurs today. The result of implementing this solution is a high impact on the existing wetland and result in expensive wetland banking to compensate for the loss of the existing wetlands. For the cost estimate we have assumed that the County would accept a 50% credit for the wetlands disturbed due to new wetlands created on site. HYDRAULIC IMPACTS The hydraulic analysis included in the following section of the report details the benefits created by this scenario. There are no negative impacts throughout the system. This option functions similar to Option A but provides greater benefits due to the further lowering of the normal water level and the increase in storage volume. The flood elevations throughout the system for this option are quantified in Appendix E. COST ESTIMATE OPTION E Remove all normal water and create a wetland bottom detention facility UNIT TOTAL HARD COSTS QTY. UNIT PRICE PRICE Pond Landscape Minor regrading of shoreline (no haul off) 2500 SY $20.00 $50, Coir fiber log 4227 LF $40.00 $169, Plant plugs EA $4.00 $40, Contractor access restoration 170 SY $1.50 $ Site Civil / MEP Erosion control 300 LF $3.00 $ Construction entrance 1 LS $4, $4, Village of Lombard

35 Fill deeper areas 9995 CY $15.00 $149, Pumps, guiderails & accessories 1 LS $50, $50, Duplex pump control panel 1 LS $85, $85, Electrical conduit & cable 1 LS $30, $30, Wet Well, 8 ft. dia 1 LS $40, $40, Wet well piping and valves 1 LS $20, $20, Inlet pipe, 30" RCP 50 FOOT $ $5, Force mains, 12" DIP 100 FOOT $75.00 $7, Discharge structure, 8 ft. dia 1 LS $10, $10, Electrical service 1 LS $20, $20, Maintenance & Monitoring (5 Years) 5 Year $10, $50, Contingency 20% $731, $146, CONSTRUCTION SUB TOTAL $877, Potential Wetland Impact Cost 4 AC $150, $600, PROFESSIONAL Design Engineering (8% of Construction Cost) $877, $70, Permitting (wetland hydrology and hydraulic analysis) (8%) $877, $70, Construction Engineering (10%) $877, $87, TOTAL $1,706, Village of Lombard

36 Option F Install relief sewers from Crystal Avenue into Terrace View Pond without modifying the pond Relief Sewers During the course of the hydraulic analysis (described in the following section), it became apparent that increasing the sewer capacity into Terrace View Pond would provide positive flood control benefits. There is a large drainage area that contributes runoff to Crystal Avenue, and the storm sewers there are undersized, backpitched in many locations, and submerged by Terrace View Pond s water level. This option considered the addition of twin 24 relief sewers directly from the low point on Crystal Avenue into Terrace View Pond. A specific route for the sewers has not been chosen; homes on the south side of Crystal will cause construction conflicts. The feasibility of the proposed sewer alignment, easements or property acquisition, and other issues need to be investigated further. 35 Village of Lombard

37 WETLAND PERMITTING This option would have minimal wetland impacts and is not anticipated to require significant permitting effort. HYDRAULIC IMPACTS The hydraulic analysis included in the following section of the report details the benefits created by this scenario. The relief sewer option performs better than lowering the normal water elevation or increasing the storage volume for the high intensity storm events for the upstream storm sewer system. Permutations of Options A and B that include the twin 24 relief sewer were also analyzed and provide a higher level of protection. Please note that Option F alone does not provide any benefits to the downstream sewer system to the south. The flood elevations throughout the system for this option are quantified in Appendix E. COST ESTIMATE OPTION F Install relief sewers from Crystal Avenue into Terrace View Pond without modifying the pond UNIT TOTAL COSTS QTY. UNIT PRICE PRICE Site Civil Erosion control 700 LF $3.00 $2, Construction entrance 1 LS $4, $4, Sewer pipe 2, 24" dia. 600 LF $ $60, Junction chamber 1 EA $15, $15, Flared end sections 2 EA $2, $5, " Check valves 2 EA $6, $12, RipRap 10 SY $ $1, Landscape Tree removal 1 EA $ $ Erosion control 1900 LF $3.00 $5, Pipe trench restoration 975 SY $10.00 $9, Path restoration 60 SY $50.00 $3, Street patch 50 SY $ $5, Contingency 30% $123, $36, CONSTRUCTION SUB TOTAL $159, Buyout Costs $250, PROFESSIONAL Surveying $5, Plats & Legals $5, Village of Lombard

38 Design Engineering (10% of Construction Cost) $159, $15, Permitting (wetland hydrology and hydraulic analysis) (8%) $159, $12, Construction Engineering (10%) $159, $15, TOTAL $464, Option G Lower NWL by 1 and add 2-24 relief sewers from Crystal Avenue into pond 2-24 Relief Sewers Lower NWL by 1 This option is a combination of Options A and F. It would provide the benefits associated with increasing both the storage volume and sewer capacity. 37 Village of Lombard

39 WETLAND PERMITTING The same permitting issues identified in Option A and F would apply. HYDRAULIC IMPACTS The hydraulic analysis included in the following section of the report details the benefits created by this scenario. Since this option combines both the additional storage and increased sewer capacity, it creates the greatest benefits. The flood elevations throughout the system for this option are quantified in Appendix E. COST ESTIMATE OPTION G Combine Options A & F TOTAL COSTS PRICE OPTION A CONSTRUCTION SUB TOTAL $350, OPTION F CONSTRUCTION SUB TOTAL $159, $510, Associated Wetland Impact $45, Buy Out Costs $250, PROFESSIONAL Design Engineering (10% of Construction Cost) $51, Permitting (wetland hydrology and hydraulic analysis) (8%) $40, Construction Engineering (10%) $51, TOTAL $947, Village of Lombard

40 V. HYDRAULIC ANALYSIS PURPOSE AND METHODOLOGY The purpose of this study was to evaluate the function of the existing Terrace View Pond as a stormwater storage basin and to quantify the flood reduction benefits that will be created by increasing the storage volume. There are areas adjacent to Terrace View Pond, particularly on Crystal Avenue to the north, that have experienced repeated flooding. This study will quantify the reduction in water elevations on Crystal Avenue and other locations throughout the watershed. As part of the study, CBBBEL has expanded and enhanced an ongoing analysis of the watershed being completed by CBBEL for the purpose of developing a master sewer separation plan. That analysis uses XP-SWMM modeling software to model the existing sewer systems and storage areas. The model was developed using the Village s sewer atlases, aerial topography, and supplemental survey data. The XP-SWMM model uses this input data to evaluate the sewer system capacity and the predicted water surface elevations throughout the system, including Terrace View Pond and the surrounding areas. EXISTING CONDITIONS There is approximately 240 acres of direct tributary area to the Terrace View Pond and surrounding storm sewer system. Additionally, the Broadview Slough is connected to the Terrace View Pond via storm sewer. This storm sewer and the Slough contribute an additional 113 acres of tributary area. The remaining 72 acres of tributary area is from overland flow north of the Great Western Trail. Terrace View Pond is part of a larger watershed referred to as the NAS (northern areas sewers) watershed. The NAS watershed generally flows from east to west and has approximately 840 acres of tributary area primarily consisting of residential area. There are several areas of ponding that occur within the watershed. The existing Terrace View Pond drains by gravity through a control structure and 48 storm sewer that flows west on Greenfield Avenue and then south Elizabeth Street; although a portion of this sewer is back pitched and allows runoff to flow backwards into Terrace View Pond. The downstream sewer system ultimately flows to a pump station on the west side of IL Route 53/I-355, where it is pumped to the East Branch DuPage River. There are several known ponding or flooding areas throughout the watershed. In general, these areas flood in storms greater than the 10-year event. Crystal Avenue, which is just north of Terrace View Pond, floods in a 1-year event. The flood depths on Crystal Avenue are significant, for instance approximately 0.8 feet (9.6 inches) in the 1-year event. 39 Village of Lombard

41 PROPOSED CONDITIONS Five alternatives were evaluated and four more modeled hydraulically to determine the benefits to the existing ponding areas. A detailed description of each alternative is provided in the previous sections of this report. The following alternatives were analyzed with XP-SWMM modeling: Lowering NWL by 1 to gain +13 ac-ft storage volume (Option A and Option C) New excavated basin adjacent and connected to Terrace View Pond (Option B) Converting Terrace View Pond to dry bottom wetland basin (Option E) Construction of a relief sewer of twin 24 pipes (Option F) Lowering NWL by 1 to gain ± 13 ac-ft storage volume and construction of a relief sewer of twin 24 pipes (Option G) 40 Village of Lombard

42 Option A and Option C Option A increases the storage capacity of Terrace View Pond by approximately 13 ac-ft. It also provides the increase in volume at the lowest elevation of the pond, therefore it provides benefits for the smallest frequent storms. The existing conditions XP-SWMM model was modified by simply lowering the normal water level (NWL) by 1 and adding a 3.3 cfs pump station. Although the purpose of the pump is to maintain the NWL, it was assumed that the pump would run during a storm event or any time that the NWL was elevated. The following table summarizes the impacts of Options A and C on water surface elevations at various locations throughout the watershed: Table 1 Option A/Option C Water Surface Elevations at Various Locations 2-year 5-year 10-year Location 1-hr 6-hr 1-hr 6-hr 1-hr 6-hr EX PR EX PR EX PR EX PR EX PR EX PR Crystal Ave Terrace View Pond Eugenia St & Elizabeth St (downstream of pond) Village of Lombard

43 Option B Option B provides approximately 8 ac-ft of storage, however it is provided throughout the elevation range between the NWL and HWL. Therefore, the full benefits from the increase in storage would not be realized for the more frequent storm events. For scenario B, the existing conditions model was modified by increasing the storage footprint of the pond. A pump was not included as was the case for Scenario A. The following table summarizes the impacts of Option B on water surface elevations at various locations throughout the watershed: Table 2 Option B Water Surface Elevations at Various Locations 2-year 5-year 10-year 1-hr 6-hr 1-hr 6-hr 1-hr 6-hr Location EX PR EX PR EX PR EX PR EX PR EX PR Crystal Ave Terrace View Pond Eugenia St & Elizabeth St (downstream of pond)) Village of Lombard

44 Option E Option E would drain the entire basin and create a dry or shallow water wetland basin. It is unknown if a dry basin is sustainable or whether local groundwater levels would cause the basin to return to a higher level. Pumping could be utilized to maintain the desired NWL, however it is unknown what pump rate would be required and how frequently the pumps would run. For the purpose of estimating the volume that this option could provide, it was assumed that the NWL would be dropped by 3. This would conservatively create an estimated 27 ac-ft of new storage volume. This option reduces the HWL in Terrace view pond significantly since the increase in volume is at the lowest elevation of the pond. In this scenario, the NWL does not submerge the outlet of the 36-inch storm sewer draining Crystal Avenue and therefore increases conveyance from Crystal Avenue into the pond. Like Option A, this option also provides the increase in volume at the lowest elevation of the pond, therefore it provides benefits for the smallest frequent storms. Greater benefits are seen during the longer duration storm events. The following table summarizes the impacts of Option E on water surface elevations at various locations throughout the watershed: Table 3 Option E Water Surface Elevations at Various Locations 2-year 5-year 10-year Location 1-hr 6-hr 1-hr 6-hr 1-hr 6-hr EX PR EX PR EX PR EX PR EX PR EX PR Crystal Ave Terrace View Pond Eugenia St & Elizabeth St (downstream of pond) Village of Lombard

45 Option F Option F would not physically modify Terrace View Pond but would include the construction of a relief sewer from Crystal Avenue directly into the pond. The analysis assumed twin 24 relief sewers, although additional or larger sewer may create larger flood reductions. Option F assumes that the normal water level of the pond would remain unchanged. Two additional scenarios were also modeled which included the addition of the relief sewers to Options A and B. Those results are included in the summary of Appendix E. The following table summarizes the impacts of Option F on water surface elevations at various locations throughout the watershed: Table 4 Option F Water Surface Elevations at Various Locations 2-year 5-year 10-year Location 1-hr 6-hr 1-hr 6-hr 1-hr 6-hr EX PR EX PR EX PR EX PR EX PR EX PR Crystal Ave Terrace View Pond Eugenia St & Elizabeth St (downstream of pond) Village of Lombard

46 Option G Option G is the combination of lowering the NWL of Terrace View Pond and constructing a relief sewer from Crystal Avenue into the pond. This option would benefit longer duration storms by increasing the storage volume in the pond. It would also benefit short duration storms by increasing sewer capacity, both by adding the relief sewer and lowering the NWL of the pond. The following table summarizes the impacts of Option G on water surface elevations at various locations throughout the watershed: Table 5 Option G Water Surface Elevations at Various Locations 2-year 5-year 10-year Location 1-hr 6-hr 1-hr 6-hr 1-hr 6-hr EX PR EX PR EX PR EX PR EX PR EX PR Crystal Ave Terrace View Pond Eugenia St & Elizabeth St (downstream of pond) Conclusions 45 Village of Lombard

47 Due to the unknowns with Scenario D concerning groundwater issues and potential for high wetland impact costs, Scenarios A and C are considered more likely alternatives for creating additional storage. The results of the modeling show that neither scenario creates significant benefits at the main flooding area on Crystal Avenue, in particular for short duration, high intensity storms. This is due to the size of the watershed, the undersized sewer system that drains Crystal Avenue, and the fact that the sewer system is several feet below Terrace View Pond. The extent of additional storage to be created (+13 ac-ft) was not expected to significantly reduce flooding for larger storms; however, it was hoped that benefits would be created for more frequent storms. For Option B, due to the way the storage would be distributed between the NWL and HWL, no benefits are realized on Crystal Avenue. Therefore, Option B is not recommended. Options A and C both show a reduction in flood elevations on Crystal for several storms, although they are generally 0.5 or less. Lowering the NWL of Terrace View consistently reduces flood depths on Crystal Avenue for longer duration storms (6-hour storms and longer). There are also benefits for shorter, more intense storms, however the benefits are limited to the 1- and 2-year storms. For instance, the 1-year 1-hour storm shows a reduction of 0.5, but only a 0.1 reduction in the 2-year 1- hour storm. Because the existing storm sewer system is submerged by the NWL of Terrace View Pond and Option A and C lower the NWL, this alternative improves the capacity of the storm sewer system. Option E provides the greater benefits than A or C, which is expected due to the amount of storage created. However, it is unknown whether a dry bottom facility is sustainable and whether this option is feasible. Option E creates significant reductions on Crystal Avenue for the 6-hour and longer storm events. For 6-hour storms, it provides a 10-year level of protection and keeps the 25-year level of ponding near 1. However, even Option E has limited benefits in a 1-hour storm. The 1-year, 1-hour storm has a reduction of 0.7 but the 2-year, 1-hour storm is reduced by only 0.2 The major conclusion to be drawn is that lowering the NWL of Terrace View Pond is beneficial for longer duration storms but has limited benefits for shorter, more intense storms. This is due to the fact that the storm sewer system surrounding Crystal Avenue lacks capacity. Many of the sewer segments are backpitched. All of the options analyzed would benefit from additional sewer capacity. Increasing the Terrace View storage has only an indirect benefit on Crystal Avenue by lowering the hydraulic grade lines in the system. For these reasons, Option F was developed. Based on the modeling results, a relief sewer from Crystal Avenue into Terrace View Pond performs better than Options A, C, or E for most storm events, in particular for the high intensity storms. For larger storms with more rainfall (50- and 100-year storm, 6-hour or longer), the relief sewer would provide little benefit because it does not increase the storage volume. Combining Option A and Option C with the relief sewer would benefit both short and long duration storms. 46 Village of Lombard

48 Option G is the combination of lowering the NWL of Terrace View Pond (either option A or C) and constructing a relief sewer from Crystal Avenue into the pond. This option creates the greatest benefits and shows improvements for both short and long duration storms. Therefore, Option G is the preferred option. It should be noted that all of the improvements analyzed showed benefits in the immediate vicinity of Terrace View Pond but did not extend far downstream. One of the comparison points used in the report is at the intersection of Eugenia and Elizabeth Streets, which is downstream of the pond. This location has experienced localized flooding in the past. However, modeling indicates that the proposed Terrace View Pond improvements would not significantly improve the sewer system capacity in that location. Adding stormwater storage anywhere throughout the watershed can only benefit the system and improve its performance. However, the scope of the improvements is not large enough to show downstream benefits at Elizabeth and Eugenia. This is likely due to the fact that the flow of water leaving the Terrace View system is controlled by the existing sewer system, which is full. To reduce downstream water levels, Terrace View storage would have to be expanded significantly so that the sewer system is no longer full, which cannot be accomplished with the proposed scope of improvements. 47 Village of Lombard

49 VI. OPTIONS COMPARISON MATRIX Ac. Ft. of Estimated Cost Per Overall OPTIONS Storage Cost** Ac. Ft. Benefit Ranking PROS CONS Option A 13 $486, $37,390 2 Very little visual change to the sites appearance. Doesn't significantly impact flood relief, especially for more frequent events. Future pump station maintenance / cost. Option B 8 $1,675, $209,460 4 Does not affect the appearance of the existing pond. Significant impact to the upland portion of the site and expensive to implement. Minor flood relief benefits. Option C 13 $500, $38,529 3 Very little visual change to the sites appearance. Doesn't significantly impact flood relief, especially for more frequent events. Disturbs land off site and will require acquisition of easements from adjoining land owners. Option D 13 $1,672, $128,680 4 Maintains depth of deep areas. Very little visual change to the sites appearance. Expensive to implement and does not have significant impact to flood relief. *Option E $1,706, $85,300 68,250 3 Significant flood relief benefits Significant change to the appearance and use of the site. High cost. Option F 0 $464, NA 2 No change to the site Significant flood relief benefits Low cost to implement Will require acquisition of adjoining lot. Most significant flood relief benefits. Will require acquisition of adjoining lot. Option G 13 $947, $37,390 *** 1 Very little visual change to the site's appearance. *A full topography of the bottom of the pond is unavailable at this time so the total volume of the pond that would be available for storage is unknown.. **Costs include construction, engineering and permitting *** Cost per acre foot only considers portions of costs associated with additional storage 48 Village of Lombard

50 VII. RECOMMENDATION Based on the results of the hydraulic analysis as well as the estimated construction costs, we recommend Option G-Crystal Avenue relief sewer and lowering the normal water of the pond +/- 1 foot via pump. This option provides the highest stormwater benefit. Note that if full funding is not available that the project could be staged between the relief sewer and lowering of the normal water level. 49 Village of Lombard

51 VIII. Appendix a. Wetland Report b. Minutes of Meeting with DuPage County EDP Division of Environmental Concerns c. EcoCAT Review/IDNR Letter d. Summary of Hydraulic Analysis e. Historic Terrace View Documents 50 Village of Lombard

52 A. WETLAND REPORT

53 August 31, 2011 Village of Lombard 1051 S. Hammerschmidt Avenue Lombard, IL Attention: Subject: David A. Dratnol, PE, Village Engineer Wetland Assessment of Terrace View Pond, Lombard, DuPage County, Illinois (CBBEL Project No ) Dear Mr. Dratnol: As requested, Christopher B. Burke Engineering, Ltd. (CBBEL) completed a wetland assessment of Terrace View Pond in Lombard, DuPage County, Illinois. The pond fringe and a portion of the pond interior are considered to be wetland; additionally a swale that drains to the Pond was also identified as wetland. The wetland perimeter was flagged and surveyed as part of the overall study. An aerial photograph delineation showing the wetland and waters limit is included as Exhibit 7. Terrace View Pond has a planted wetland perimeter consisting of wet prairie and prairie vegetation. Additonally, the pond contains white water lily, duckweed and algae. The prairie and wet prairie established vegetation is a fairly diverse and is dominated by natives and received a high floristic rating. Because the native vegetation was installed, conversations with County Staff and the Corps of Engineers will be necessary to determine the impact the presence this vegetation may have on permitting of any proposed improvements. CBBEL staff met on site with Mary Beth Falsey of DuPage County on July 26, 2011 who confirmed the staked wetland boundaries. The pond/wetland area appears to qualify as a critical based on the floristic inventory. However it is possible that the wetland area is exempt from regulation because the area was excavated. If the area is not exempt from regulation, then any impact to the wetlands will require certification from the County, as well as mitigation for those impacts. If the area is considered to be critical, the mitigation ratio will be 3:1. Under the current version of the Ordinance, impacts to critical wetland are prohibited unless certain conditions are met. This project is somewhat unique in that the wetland area is critical because the area was planted and is established with a higher quality plant community. If it were not for these improvements the area would be regulatory, which would reduce the regulatory burden for permitting. Discussions with the County will be necessary to determine how the wetland area will be classified and reviewed. Christopher B. Burke Engineering, Ltd. Village of Lombard Terrace View Pond 1

54 The attached report presents the methodology and reference material used to complete the assessment. Routine On-Site Data Forms, required by the USACE, are also included. This assessment is based on field conditions at the time of the CBBEL site visit and our understanding of current federal, state and local regulations. If you have any questions, please call. Sincerely, Jedd Anderson Vice President Head, Environmental Resources Department Christopher B. Burke Engineering, Ltd. Village of Lombard Terrace View Pond 2

55 WETLAND ASSESSMENT REPORT TERRACE VIEW POND, LOMBARD, IL (CBBEL Project No ) WETLAND DELINEATION On July 20, 2011, Christopher B. Burke Engineering, Ltd. (CBBEL) completed a wetland field investigation of the Terrace View Pond to determine on-site wetland and waters of the U.S. boundaries. This report documents our findings. The subject site is located south of W. Crystal Ave, east of N. Elizabeth St., north of W. Greenfield Ave, and west of Main St. in Lombard, DuPage County, Illinois, as shown on Exhibit 1. Wetland and waters of the U.S. boundaries were delineated in accordance with the methodology established in the Regional Supplement to the 1987 U.S. Army Corps of Engineers (COE) Wetland Delineation Manual. Mary Beth Falsey of DuPage County confirmed the wetland boundaries on July 26, The wetland and waters of the U.S. boundaries are shown on Exhibit 7. Information collected on site is listed in the attached data forms. METHODOLOGY The Regional Supplement to the Corps of Engineers Wetland Delineation Manual: Midwest Region (August 2010), identifies the mandatory technical criteria for wetland identification. The three essential characteristics of a jurisdictional wetland are hydrophytic vegetation, hydric soils and wetland hydrology as described below: Hydrophytic Vegetation: The hydrophytic vegetation criterion is based on a separation of plants into five basic groups: (1) Obligate wetland plants (OBL) almost always occur (estimated probability >99%) in wetlands under natural conditions; (2) Facultative wetland plants (FACW) usually occur in wetlands (estimated probability 67-99%), but occasionally are found in non-wetlands; (3) Facultative plants (FAC) are equally likely to occur in wetlands or nonwetlands (estimated probability 34-66%); (4) Facultative upland plants (FACU) usually occur in non-wetlands (estimated probability 67-99%), but occasionally are found in wetlands; and (5) Obligate upland plants (UPL) almost always occur (estimated probability >99%) in non-wetlands under natural conditions. Four procedures completed in the following order are used to determine if hydrophytic vegetation is present: Christopher B. Burke Engineering, Ltd. Village of Lombard Terrace View Pond 3

56 1) Rapid Test: The Rapid Test for hydrophytic vegetation is met if all dominant species across all strata are OBL or FACW, or a combination of the two based on a visual assessment. 2) Dominance Test: Using the 50/20 Rule, if greater than 50% of the plants present are FAC, FACW, or OBL, the subject area meets the hydrophytic vegetation criterion. 3) Prevalence Index: Each plant species in a sampling plot is assigned a numeric value (OBL=1; FACW=2; FAC=3; FACU=4; UPL=5). Based on the sampling data, the absolute cover is calculated for each species in each stratum and using the specified formula, if the Prevalence Index is 3 or less, hydrophytic vegetation is present. 4) Morphological Adaptations: Various species may develop physical characteristics after growing in wetland areas such as multi-stemmed trunks, shallow roots and buttressed stems. Hydrophytic vegetation is present if an adaptation is observed in more than 50% of FACU species growing in an area that contains hydric soil and wetland hydrology. Hydric Soils: Hydric soils are defined in the manual as "soils that are saturated, flooded or ponded long enough during the growing season to develop anaerobic conditions in the upper part." Field indicators of hydric soil are found in the NTCHS Field Indicators of Hydric Soils in the United States (USDA Natural Resources Conservation Service 2006b or current version). Wetland Hydrology: The wetland hydrology criterion is often the most difficult to determine. Typically, the presence of water for a portion of the growing season creates anaerobic conditions. Anaerobic conditions lead to the prevalence of wetland plants. Morphological adaptations of plants, driftlines and watermarks are examples of wetland hydrology field indicators. RESULTS AND DISCUSSION Terrace View Pond Terrace View Pond was constructed in the 1960s or 70s based on a review of historic aerial photographs. Based on the photographs, the pond was excavated out of an existing wetland area. Until recently, the pond had a mown shoreline then was converted to having a naturalized shoreline and prairie buffer. It appears that white water lily was also planted within the pond. The wetland and prairie communities are dominated by native species and based on field evidience has undergone routine maintenance to promote and maintain the native species dominance. The established vegetation is diverse and consequently was calculated to have a relatively high floristic quality. Soils around the entire pond perimeter were not uniform showing evidence of disturbance. The material consisted of clays, sand and gravel. The material did not have normal soil profiles. Many places had little to no topsoil present within the wetland fringe, probably from years of wave action/erosion. No typical hydric soil characteristics Christopher B. Burke Engineering, Ltd. Village of Lombard Terrace View Pond 4

57 were noted. Though due to its nature had evidence of hydrology and was therefore assumed to be hydric. The following is a list of identified plant species observed and their corresponding wetland indicator categories. A coefficient of conservatism (C-value) is also included for each plant species. C-values were established by Swink and Wilhelm (1999) to quantify a wetland s native attributes for comparative purposes. Each plant species is rated on a scale of 0 to 10, 0-representing non-native or noxious species commonly found in a variety of habitats, and 10 representing plants found only under specific ecological conditions. The C-values of plants found in wetland areas can give some insight as to the overall quality or value of the wetland. Wetlands containing an abundance of plants with a low C-value suggest that these wetlands have been disturbed in the past. Wetlands containing an abundance of plants with a high C-value suggest that specific ecological conditions necessary for their survival are intact thus disturbance is probably minimal and the wetland maintains at least some of its original integrity. FLORISTIC QUALITY DATA Native % Adventive % 50 NATIVE SPECIES Tree 3 4.2% Tree 4 5.6% 71 Total Species Shrub 2 2.8% Shrub 1 1.4% 3.1 NATIVE MEAN C W-Vine 1 1.4% W-Vine 0 0.0% 2.2 W/Adventives H-Vine 0 0.0% H-Vine 0 0.0% 22.1 NATIVE FQI P-Forb % P-Forb % 18.5 W/Adventives B-Forb 0 0.0% B-Forb 3 4.2% -1.2 NATIVE MEAN W A-Forb 5 7.0% A-Forb 1 1.4% -0.2 W/Adventives P-Grass 6 8.5% P-Grass 3 4.2% AVG: Faculative (+) A-Grass 0 0.0% A-Grass 0 0.0% P-Sedge % P-Sedge 0 0.0% A-Sedge 0 0.0% A-Sedge 0 0.0% Cryptogam 0 0.0% C SCIENTIFIC NAME W WETNESS PHYSIOGNOMY COMMON NAME 0 Acer negundo -2 FACW- Nt Tree BOX ELDER 0 ACER PLATANOIDES 5 UPL Ad Tree NORWAY MAPLE 0 Acer saccharinum -3 FACW Nt Tree SILVER MAPLE 0 AGROSTIS ALBA -3 FACW Ad P-Grass REDTOP 0 Amaranthus hybridus 5 UPL Nt A-Forb GREEN AMARANTH 0 Ambrosia artemisiifolia elatior 3 FACU Nt A-Forb COMMON RAGWEED 0 Ambrosia trifida -1 FAC+ Nt A-Forb GIANT RAGWEED 5 Andropogon gerardii 1 FAC- Nt P-Grass BIG BLUESTEM GRASS 5 Andropogon scoparius 4 FACU- Nt P-Grass LITTLE BLUESTEM GRASS 4 Apocynum cannabinum 0 FAC Nt P-Forb INDIAN HEMP 0 ARCTIUM MINUS 5 UPL Ad B-Forb COMMON BURDOCK 7 Asarum canadense 5 UPL Nt P-Forb WILD GINGER 4 Asclepias incarnata -5 OBL Nt P-Forb SWAMP MILKWEED 0 Asclepias syriaca 5 UPL Nt P-Forb COMMON MILKWEED 4 Aster novae-angliae -3 FACW Nt P-Forb NEW ENGLAND ASTER 0 Aster pilosus 2 FACU+ Nt P-Forb HAIRY ASTER 6 Carex lacustris -5 OBL Nt P-Sedge COMMON LAKE SEDGE 5 Carex stricta -5 OBL Nt P-Sedge COMMON TUSSOCK SEDGE 0 CICHORIUM INTYBUS 5 UPL Ad P-Forb CHICORY 0 CIRSIUM ARVENSE 5 UPL Ad P-Forb FIELD THISTLE 0 CONVOLVULUS ARVENSIS 5 UPL Ad P-Forb FIELD BINDWEED 0 Cyperus esculentus -1 [FAC+] Nt P-Sedge FIELD NUT SEDGE 3 Desmanthus illinoensis 5 UPL Nt P-Forb SENSITIVE PLANT 2 Eleocharis acicularis -5 OBL Nt P-Sedge NEEDLE SPIKE RUSH 3 Epilobium coloratum -5 OBL Nt P-Forb CINNAMON WILLOW HERB 1 Fragaria virginiana 1 FAC- Nt P-Forb WILD STRAWBERRY 1 Fraxinus pennsylvanica subintegerrima 0 FAC Nt Tree GREEN ASH 1 Geum canadense 0 FAC Nt P-Forb WOOD AVENS Christopher B. Burke Engineering, Ltd. Village of Lombard Terrace View Pond 5

58 4 Glyceria striata -3 [FACW] Nt P-Grass FOWL MANNA GRASS 4 Juncus dudleyi 0 [FAC] Nt P-Forb DUDLEY'S RUSH 7 Juncus effusus -5 OBL Nt P-Forb COMMON RUSH 4 Juncus torreyi -3 FACW Nt P-Forb TORREY'S RUSH 4 Leersia oryzoides -5 OBL Nt P-Grass RICE CUT GRASS 5 Lemna minor -5 OBL Nt A-Forb SMALL DUCKWEED 0 LYTHRUM SALICARIA -5 OBL Ad P-Forb PURPLE LOOSESTRIFE 0 MELILOTUS ALBA 3 FACU Ad B-Forb WHITE SWEET CLOVER 0 MELILOTUS OFFICINALIS 3 FACU Ad B-Forb YELLOW SWEET CLOVER 4 Monarda fistulosa 3 FACU Nt P-Forb WILD BERGAMOT 0 MORUS ALBA 0 FAC Ad Tree WHITE MULBERRY 7 Nymphaea tuberosa -5 OBL Nt P-Forb WHITE WATER LILY 0 Oxalis stricta 5 UPL Nt P-Forb COMMON WOOD SORREL 5 Panicum virgatum -1 FAC+ Nt P-Grass SWITCH GRASS 0 PHALARIS ARUNDINACEA -4 FACW+ Ad P-Grass REED CANARY GRASS 0 POA PRATENSIS 1 FAC- Ad P-Grass KENTUCKY BLUE GRASS 0 POLYGONUM CUSPIDATUM 3 FACU Ad Shrub JAPANESE KNOTWEED 0 Polygonum lapathifolium -4 FACW+ Nt A-Forb HEARTSEASE 0 POLYGONUM PERSICARIA 1 [FAC-] Ad A-Forb LADY'S THUMB 0 PRUNELLA VULGARIS 5 [UPL] Ad P-Forb LAWN PRUNELLA 4 Ratibida pinnata 5 UPL Nt P-Forb YELLOW CONEFLOWER 0 ROBINIA PSEUDOACACIA 4 FACU- Ad Tree BLACK LOCUST 0 RUMEX CRISPUS -1 FAC+ Ad P-Forb CURLY DOCK 1 Salix interior -5 OBL Nt Shrub SANDBAR WILLOW 1 Sambucus canadensis -2 FACW- Nt Shrub ELDERBERRY 6 Scirpus acutus -5 OBL Nt P-Sedge HARD-STEMMED BULRUSH 4 Scirpus atrovirens -5 OBL Nt P-Sedge DARK GREEN RUSH 6 Scirpus cyperinus -5 OBL Nt P-Sedge WOOL GRASS 4 Scirpus fluviatilis -5 OBL Nt P-Sedge RIVER BULRUSH 5 Scirpus validus creber -5 OBL Nt P-Sedge GREAT BULRUSH 5 Silphium integrifolium 5 UPL Nt P-Forb ROSIN WEED 5 Silphium perfoliatum -2 FACW- Nt P-Forb CUP PLANT 1 Solidago altissima 3 FACU Nt P-Forb TALL GOLDENROD 4 Solidago graminifolia -2 FACW- Nt P-Forb GRASS-LEAVED GOLDENROD 4 Spartina pectinata -4 FACW+ Nt P-Grass PRAIRIE CORD GRASS 0 TARAXACUM OFFICINALE 3 FACU Ad P-Forb COMMON DANDELION 2 Tradescantia ohiensis 2 FACU+ Nt P-Forb COMMON SPIDERWORT 0 TRIFOLIUM HYBRIDUM 1 FAC- Ad P-Forb ALSIKE CLOVER 0 TRIFOLIUM REPENS 2 FACU+ Ad P-Forb WHITE CLOVER 0 ULMUS PUMILA 5 UPL Ad Tree SIBERIAN ELM 4 Verbena hastata -4 FACW+ Nt P-Forb BLUE VERVAIN 3 Vernonia altissima 0 FAC Nt P-Forb SMOOTH TALL IRONWEED 2 Vitis riparia -2 FACW- Nt W-Vine RIVERBANK GRAPE Drainage Swale To the southeast of the pond is a drainage swale that drains towards the pond. A portion of this swale was flagged as wetland. Soils within the swale were found to be hydric and saturated. The portion of the swale that was flagged contained a predominace of wetland vegetation. Dominant vegetation consisted of Juncus dudleyi and Scirpus cyperinus. The following is a list of identified vegetation. FLORISTIC QUALITY DATA Native % Adventive % 13 NATIVE SPECIES Tree 0 0.0% Tree 0 0.0% 15 Total Species Shrub 0 0.0% Shrub 0 0.0% 4.2 NATIVE MEAN C W-Vine 0 0.0% W-Vine 0 0.0% 3.6 W/Adventives H-Vine 0 0.0% H-Vine 0 0.0% 15.0 NATIVE FQI P-Forb % P-Forb 1 6.7% 13.9 W/Adventives B-Forb 0 0.0% B-Forb 0 0.0% -4.2 NATIVE MEAN W A-Forb 1 6.7% A-Forb 0 0.0% -3.7 W/Adventives P-Grass % P-Grass 1 6.7% AVG: Fac. Wetland (+) A-Grass 0 0.0% A-Grass 0 0.0% P-Sedge % P-Sedge 0 0.0% A-Sedge 1 6.7% A-Sedge 0 0.0% Cryptogam 0 0.0% Christopher B. Burke Engineering, Ltd. Village of Lombard Terrace View Pond 6

59 C SCIENTIFIC NAME W WETNESS PHYSIOGNOMY COMMON NAME 10 Agrostis alba palustris -5 [OBL] Nt P-Grass BENT GRASS 4 Asclepias incarnata -5 OBL Nt P-Forb SWAMP MILKWEED 5 Carex stricta -5 OBL Nt P-Sedge COMMON TUSSOCK SEDGE 0 Cyperus esculentus -1 [FAC+] Nt P-Sedge FIELD NUT SEDGE 3 Eleocharis obtusa -5 OBL Nt A-Sedge BLUNT SPIKE RUSH 5 Iris virginica shrevei -5 OBL Nt P-Forb BLUE FLAG 4 Juncus dudleyi 0 [FAC] Nt P-Forb DUDLEY'S RUSH 4 Leersia oryzoides -5 OBL Nt P-Grass RICE CUT GRASS 5 Lycopus americanus -5 OBL Nt P-Forb COMMON WATER HOREHOUND 0 POA PRATENSIS 1 FAC- Ad P-Grass KENTUCKY BLUE GRASS 4 Polygonum amphibium stipulaceum -5 OBL Nt P-Forb WATER KNOTWEED 0 Polygonum lapathifolium -4 FACW+ Nt A-Forb HEARTSEASE 0 RUMEX CRISPUS -1 FAC+ Ad P-Forb CURLY DOCK 4 Scirpus atrovirens -5 OBL Nt P-Sedge DARK GREEN RUSH 6 Scirpus cyperinus -5 OBL Nt P-Sedge WOOL GRASS REFERENCE MATERIALS The following reference materials were reviewed and used to assist in the wetland field reconnaissance. They are included as Exhibits 1-5. LOCATION The subject site is located south of W. Crystal Ave, east of N. Elizabeth St., north of W. Greenfield Ave, and west of Main St. in Lombard DuPage County, Illinois, as shown on Exhibits 1-7. Geographically, the property is located in Section 6, Township 39 North, Range 11, and east of the Third Principal Meridian (Latitude N and Longitude W). NATIONAL WETLAND INVENTORY The National Wetland Inventory (NWI), Lombard Quadrangle (1983), as shown on Exhibit 2, indicates that an excavated pond mapped within the property. The NWI serves only as a large-scale guide and actual wetland locations and types often vary from that mapped. The following lists the identified pond: PUBGx Palustrine, Unconsolidated Bottom, Intermittantly Exposed, Excavated DUPAGE COUNTY WETLAND INVENTORY The DuPage County Wetland Inventory (DCWI) also provides a reference to the potential presence of wetland. As shown on Exhibit 3, the DCWI indicates on the York Township map that wetland area is present within the subject site. SOIL SURVEY The Soil Survey of DuPage County, Illinois (2001), as shown on Exhibit 3, was reviewed to determine the location of hydric soils within the study area. Mapped hydric soil can be indicative of wetland conditions. The following types of soil are mapped within the study area: Christopher B. Burke Engineering, Ltd. Village of Lombard Terrace View Pond 7

60 W - Water 232A - Ashkum Silty Clay Loam Hydric 805B - Orthents, Clayey, Undulating 854B - Markham/Ashkum/Beecher Complex Hydric Inclusions 903A - Muskego/Houghton Mucks Hydric 1903A - Muskego/Houghton Mucks, Wet - Hydric UNITED STATES GEOLOGICAL SURVEY MAP The United States Geological Survey map (USGS) for the Lombard Quadrangle (1993), as shown on Exhibit 5, was reviewed to determine historic local drainage patterns. The USGS map indicates that the site drains to the south. FLOOD INSURANCE RATE MAP The Flood Insurance Rate Map (FIRM) for DuPage County and Incorporated Areas, Illinois, Map Number 17043C0607H, effective December 16, 2004, as shown on Exhibit 6, was reviewed to determine the location of regulatory floodplain on site. The presence of floodplain can be indicative of wetland hydrology. The FIRM indicates that there is Zone x 500-year floodplain associated with the pond. N:\Lombard\110256\Admin\Wet Del jma doc Christopher B. Burke Engineering, Ltd. Village of Lombard Terrace View Pond 8

61 B. MINUTES OF MEETING WITH DUPAGE COUNTY EDP DIVISION OF ENVIRONMENTAL CONCERNS

62 August 23, 2011 TO: FROM: SUBJECT: ATTENDENCE: Ray Schwab, Village of Lombard Douglas Gotham CBBEL August 18 th Meeting with DuPage County Department of Environmental Concerns regarding Terrace View Pond Wetland Jennifer Boyer, PWS, DuPage County EDP Jedd Anderson, CBBEL Jeff Julkowski, CBBEL Doug Gotham, CBBEL Items Discussed; Jedd described to the Jennifer that the Terrace View Pond area was historically a wetland and was excavated and converted in the 1960 s into a pond to serve as a stormwater facility. Jedd described that the perimeter wetland fringe surrounding the pond is planted rather than naturally occurring and is probably critical for floristic diversity. The lily pads in the water indicate that wetland conditions extend into the water. Jennifer informed CBBEL that regardless of the wetland plantings artificial creation that it is still recognized by the County and has to be respected and any impact to it has to be permitted. Jennifer indicated that the village will have to look at alternatives to impacting the wetland and document that any particular method to using the pond is the only practical solution, when taking into consideration a variety of factors, to alleviate flood damages in the residential areas. Proof of damages to the residential areas will have to be described. CBBEL described to Jennifer the variety of options that the village is exploring for use of the pond for flood control. Jennifer indicated that each of the options have a potential impact to the existing wetland. Jeff offered an alternative where the current water level of the pond is maintained, but a pump be installed to lower the water level in the advance of a storm. Jennifer suggested that CBBEL speak to DuPage County stormwater engineers about creating an operating plan which would pump the pond down only just prior to a flood event. Apparently this situation occurs on other county stormwater facilities. However, Jennifer speculated that artificially lowering the water levels by pump may introduce too much bounce into the system and cause the water levels to fluctuate more than they do currently during a storm event. The topography of the pond may mean that the wetland area will shrink. These factors may make mitigation difficult. Lowering the NWL may have other consequences such as raising the temperature of the water, lowered dissolved oxygen, increased algae growth, fish kills, etc. Jennifer discussed a situation where ideally the wetland may be impacted temporarily and most or all of the wetland will return to its current size and quality with management, an adaptive mitigation plan may be approved which would require a delineation in year 3 to verify success.

63 C. ECOCAT REVIEW/IDNR LETTER

64 Applicant: Christopher B. Burke Engineering, Ltd. IDNR Project #: Contact: Jedd M. Anderson Date: 08/31/2011 Address: 9575 W. Higgins Road, Suite 600 Rosemont, IL Project: Address: Terrace View Pond Greenfield Ave, Lombard Description: Proposed modification of stormwater management pond to improve stormwater storage Natural Resource Review Results Consultation for Endangered Species Protection and Natural Areas Preservation (Part 1075) The Illinois Natural Heritage Database shows the following protected resources may be in the vicinity of the project location: Churchill Prairie INAI Site Churchill Prairie Nature Preserve Common Moorhen (Gallinula chloropus) An IDNR staff member will evaluate this information and contact you within 30 days to request additional information or to terminate consultation if adverse effects are unlikely. Location The applicant is responsible for the accuracy of the location submitted for the project. County: DuPage Township, Range, Section: 39N, 11E, 6 IL Department of Natural Resources Contact Rick Pietruszka Division of Ecosystems & Environment Local or State Government Jurisdiction Village of Lombard David Dratnol 1051 S Hammerschmidt Ave. Lombard, Illinois Page 1 of 2

65 IDNR Project Number: Disclaimer The Illinois Natural Heritage Database cannot provide a conclusive statement on the presence, absence, or condition of natural resources in Illinois. This review reflects the information existing in the Database at the time of this inquiry, and should not be regarded as a final statement on the site being considered, nor should it be a substitute for detailed site surveys or field surveys required for environmental assessments. If additional protected resources are encountered during the project s implementation, compliance with applicable statutes and regulations is required. Terms of Use By using this website, you acknowledge that you have read and agree to these terms. These terms may be revised by IDNR as necessary. If you continue to use the EcoCAT application after we post changes to these terms, it will mean that you accept such changes. If at any time you do not accept the Terms of Use, you may not continue to use the website. 1. The IDNR EcoCAT website was developed so that units of local government, state agencies and the public could request information or begin natural resource consultations on-line for the Illinois Endangered Species Protection Act, Illinois Natural Areas Preservation Act, and Illinois Interagency Wetland Policy Act. EcoCAT uses databases, Geographic Information System mapping, and a set of programmed decision rules to determine if proposed actions are in the vicinity of protected natural resources. By indicating your agreement to the Terms of Use for this application, you warrant that you will not use this web site for any other purpose. 2. Unauthorized attempts to upload, download, or change information on this website are strictly prohibited and may be punishable under the Computer Fraud and Abuse Act of 1986 and/or the National Information Infrastructure Protection Act. 3. IDNR reserves the right to enhance, modify, alter, or suspend the website at any time without notice, or to terminate or restrict access. Security EcoCAT operates on a state of Illinois computer system. We may use software to monitor traffic and to identify unauthorized attempts to upload, download, or change information, to cause harm or otherwise to damage this site. Unauthorized attempts to upload, download, or change information on this server is strictly prohibited by law. Unauthorized use, tampering with or modification of this system, including supporting hardware or software, may subject the violator to criminal and civil penalties. In the event of unauthorized intrusion, all relevant information regarding possible violation of law may be provided to law enforcement officials. Privacy EcoCAT generates a public record subject to disclosure under the Freedom of Information Act. Otherwise, IDNR uses the information submitted to EcoCAT solely for internal tracking purposes. Page 2 of 2

66 August 31, 2011 Jedd M. Anderson Christopher B. Burke Engineering, Ltd W. Higgins Road, Suite 600 Rosemont, IL Re: Terrace View Pond Project Number(s): County: DuPage Dear Applicant: This letter is in reference to the project you recently submitted for consultation. The natural resource review provided by EcoCAT identified protected resources that may be in the vicinity of the proposed action. The Department has evaluated this information and concluded that adverse effects are unlikely. Therefore, consultation under 17 Ill. Adm. Code Part 1075 is terminated. Provided all federal, state and local environmental laws, regulations and ordinances are complied with, adverse impacts to listed state resources does not appear likely. This consultation is valid for two years unless new information becomes available that was not previously considered; the proposed action is modified; or additional species, essential habitat, or Natural Areas are identified in the vicinity. If the project has not been implemented within two years of the date of this letter, or any of the above listed conditions develop, a new consultation is necessary. The natural resource review reflects the information existing in the Illinois Natural Heritage Database at the time of the project submittal, and should not be regarded as a final statement on the site being considered, nor should it be a substitute for detailed site surveys or field surveys required for environmental assessments. If additional protected resources are encountered during the project s implementation, you must comply with the applicable statutes and regulations. Also, note that termination does not imply IDNR's authorization or endorsement of the proposed action. Please contact me if you have questions regarding this review. Rick Pietruszka Division of Ecosystems and Environment Printed on recycled and recyclable paper