PRELIMINARY STORMWATER MANAGEMENT REPORT
Contents: Project: Lexington Trace 1 Project Overview & Narrative Estes Road 2 General Property Exhibits 3 Church Parcel Detention Plans (Reduced) Location: Warrenville, Illinois Appendix 4 Existing Conditions Drainage Exhibit (24x36) Prepared For: 5 Proposed Conditions Drainage Exhibit (24x36) Lexington Homes 1731 Marcey Street, Suite 200 Chicago, IL 60614
Date: May 31, 2017 Revised: July 12, 2017
Prepared By: Len Kleinjan, PE, PLS, CFM Haeger Project No.: 16-118
ENGINEERING | SURVEYING | CONSTRUCTION 100 East State Parkway, Schaumburg, IL 60173 ⋅ tel 847.394.6600 fax 847.394.6608 haegerengineering.com Lexington Trace – Warrenville July 12, 2017 Preliminary Storm Water Management Report
STORM WATER PROJECT NARRATIVE
Summary Lexington Trace is a 20.9 acre residential townhome development proposed at the southwest corner of Route 59 and Route 56 (Butterfield Road) in the City of Warrenville, IL. The property is subdivided and consists of 10 lots that’s that have been assimilated and the proposal considers building a total of 106 townhome units consisting of two product types. The property is mostly undeveloped and in its natural state. Two large wetlands are located on the property and their preservation is a key factor in the design of the stormwater management system.
Both wetlands will be nominally impacted in order to be able to develop the property but onsite wetland mitigation is proposed. The wetlands have been delineated by Gary R Weber Associates (GRWA) and located by Haeger Engineering. See separate wetland reports by GRWA.
Flood maps indicate the presence of flood plain within the depressional areas of the property and a portion of the Route 59 depression will be filled. There is also a detention basin located on the Church property to the west and the overflow from this detention basin extends onto the property. The flood plain volume lost will be compensated for by excavation and expansion of the depressional area alongside Butterfield Road.
Storm water detention is proposed for the development and three detention basins are shown on the preliminary engineering plans. The combined volume provided is 6.5 acre feet of storage which will meet the County requirements. The project will be designed to meet the DuPage County stormwater management requirements.
The Emmanuel Baptist Church of Warrenville owns the property to the west. The property contains a detention basin with a restrictor and overflow structure that is drained via a 12” storm sewer that passes through the subject property. This bypass sewer will be re-routed to maintain its discharge. The grading for the proposed development is also designed so as to maintain the existing overflow routes from the Church parcel.
In order to sustain the Route 59 wetland the project proposes to continue to drain stormwater runoff from the western portions of the site through the wetland. The runoff will first be directed to pre-treatment basins which will allow for sediment to settle and the water will then drain into the wetland through a level spreader. In extreme events, runoff will drain through the wetland and then discharge into the detention basin.
The development contemplates making significant storm water management improvements to the area that will provide detention in compliance with the DuPage County Stormwater Management Ordinance, as well as sustain and enhance the retained and created wetlands. The storm water management improvements will improve the flood conditions in the area.
Existing Conditions: The existing drainage conditions for the site was analyzed and existing depressional areas, overflow routes and storm sewers were reviewed to determine flow and flood patterns for the site. See attached existing conditions drainage exhibit.
Storm drainage generally flows from west to east across the proposed development. There are three areas that flood during storm events that are located on and adjacent to the property and they have been considered in the analysis. They are: • The detention basin to the west located on the Emmanuel Baptist Church property that discharges to the east via a 12” storm sewer that flows through the subject site. This detention basin has a 5”
Lexington Trace – Warrenville July 12, 2017 Preliminary Storm Water Management Report
restrictor outfall and an overflow catch basin at elevation 720. However, in extreme events the 12” storm sewer that drains this site is overwhelmed and the pond overflows onto the subject property. The Church detention pond plans (copy attached) indicate that the intent was for the pond to be contained within the Church parcel but current topography indicates that it overflows to the west and results in some flood storage on site. The flood storage lost by the development will be compensated for onsite. The detention pond overflows to the west at an elevation of approximately 721.1 • An approximate 1.3 acre wetland located adjacent to Route 59 (Wetland B). This wetland is located within a depression that flows through the parcel to the north and overtops at an elevation of approximately 718.2. When the depression overflows, it flows into the parking lot to the north and enters the 12” bypass storm sewer. • A large wetland is located along Butterfield Road. Wetland A (Gentile Wetland) is located adjacent to Butterfield Road and has an area of approximately 3.2 acres. It is located in a depression and receives runoff from the adjacent area, but also from the back water effect of the 12” bypass sewer. The depressional area would overtop the berm along Route 56 at approximate elevation 716.5.
The existing 12” bypass storm sewer is constrained by an existing 10” clay tile at the eastern edge of Wetland A. This 10” tile functions as a restrictor for the bypass sewer and causes runoff to back water into the wetland.
Proposed Improvements – Storm Water Management: The proposed development considers and accommodates the wetlands, flood plain impacts and detention requirements. See attached preliminary plans.
Wetlands: The wetlands were field located and flagged by GRWA. Three wetlands exist, Wetland A along Butterfield Road that has on onsite area of 3.17 acres, Wetland B along Route 59 that has an onsite area of 0.92 acres and a small remnant wetland adjacent to A, Wetland C that has an area of 0.005 acres. Both these wetlands need to be partially impacted in order to accommodate the proposed development. Wetland A has a 0.075 acre impact for the road and another 0.024 acres for an excavation to connect the created wetland to the existing wetland, Wetland B has a 0.53 acres impact and tiny wetland C has to be removed. Total impact is 0.63 acres. This is required to be compensated for at a ratio of 1.5 to 1, although the 0.5 ratio can be provided as a wetland enhancement of the existing wetland. To compensate for the wetland impact, new wetlands are proposed to be created on site. The created wetland has a gross area of 0.84 acres, but because of the required 50’ buffer, the net wetland area used to compensate for the impact is 0.64 acres. This satisfies the requirement on a 1:1 basis, and to satisfy the additional 0.5 requirement a wetland enhancement of 0.38 acres is proposed for Wetland B. In order to sustain the wetlands the project is designed to provide storm runoff to the wetlands. Wetland B is designed as a flow through wetland with pre-treatment basins that are intended to treat the water and remove sediments and trash before the runoff enters the wetland. The runoff is introduced to the wetland along the edges using a level spreader to distribute the flow. In extreme events the wetland will fill up and then overflow through a new overflow structure that will drain the wetland to Detention Basin A. During final engineering an analysis will be performed on the existing and proposed hydrology of Wetland B and adequate drainage area from the upstream areas will be directed towards Wetland B in order to sustain it. The amount of area directed towards Wetland B can easily be altered during final design to establish the preferred area to drain through Wetland B so as to best mimic the existing hydrology and avoid an indirect hydrologic impact on the wetland. The created wetland is being excavated to an elevation of approximately 713.8 and connected to the existing wetland. The outfall to Wetland A is at an elevation of 713.36. Runoff will be introduced to the created wetland through level spreaders draining both Detention Ponds A and B. We are also proposing to route the discharge from the church detention basin directly to the created wetland so that we can provide an improved
Lexington Trace – Warrenville July 12, 2017 Preliminary Storm Water Management Report outfall condition for the church. The created wetland will include meander channels to facilitate drainage and encourage an attractive wetland environment.
Floodplain: A portion of the flood plain depressional along Route 59 is planned to be filled to accommodate the development. This flood plain fill has to be compensated for and compensatory storage provided at a 1.5:1 ratio for flood plain storage. The flood storage provided by the church detention pond overflow that extends onto the subject site also needs to be filled and compensated for at a 1:1 ratio.
The volumes of fill and compensatory storage is as tabled below:
Flood Storage Fill (On- Comp Volume Comp Volume Site) (Acre-Feet) Required (Acre-Feet) Provided (Acre-Feet) Wetland B (Route 59) 0.99 1.49 Church Pond Overflow 0.31 0.31 Created Wetland 1.81 Total 1.30 1.80 1.81
The compensatory storage for this flood plain fill is proposed to be provided within the created wetland area located adjacent to Wetland A.
Detention: Detention for the site is proposed in 3 detention basins. For the preliminary plans a nomograph was used to determine the detention required. The nomograph is based on an allowable release of 0.1 cfs per acre and we considered a conservative value of 50% hydraulically connected impervious areas. The detention volume required from the nomograph is then 0.40 acre-feet/acre of tributary area. We determined the tributary areas and calculated the detention volumes required. We also calculated the amount of detention provided based on the preliminary grading plans. The table below tabulates the volumes of detention required and provided within the three basins:
Tributary Area (On-Site) Detention Required Detention Provided (Acres) (Acre-Feet) (Acre-Feet) Detention Basin A 11.16 4.46 4.54 Detention Basin B 2.08 0.83 0.91 Detention Basin C 2.50 1.00 1.02 Total 15.74 6.30 6.47
On-site storm sewers will be installed throughout the property to collect runoff and drain them to the detention basins. Overflow routes will be provided to discharge excess flow to the detention basins and allow provide flood routes for both onsite and offsite areas.
Note that the existing wetland depressions (flood plain) are already providing natural detention for the site and there is limited off-site flow to these depressions. The combination of new detention, compensatory storage and maintaining the existing depressional storage results in a situation that provides excess flood storage that will not be able to be fully utilized.
Existing 12” Bypass Storm Sewer: An existing 12” bypass storm sewer that drains the property from the west drains through the site. This storm sewer has to be relocated because it would intercept the proposed detention basin in its present location. We have proposed to connect this sewer directly to the created wetland so as to improve the flow conditions from the church. The 12” sewer is presently constrained and competes with discharge
Lexington Trace – Warrenville July 12, 2017 Preliminary Storm Water Management Report
from properties to the east. A direct connection will provide a sewer dedicated to taking the church discharge and provide a much reduced sewer length with improved flow characteristics.
Existing Wetland Drain Tile Sewer: An existing 10” clay tile receives flow from Wetland A at its eastern edge and routes flow offsite to the southwest corner of Route 59 & Butterfield Road. This tile will be televised to evaluate its condition and will be cleaned, repaired or replaced and possibly re-routed depending on the findings of the inspection and direction from the City.
Conclusion The preliminary plans have considered the wetlands, flood plain fill, compensatory storage and detention requirements and accommodations have been made in the plans to satisfy these criteria.
2
GENERAL PROPERTY EXHIBITS
• Aerial Property Exhibit • DuPage County Wetlands Exhibit • FEMA FIRM Exhibit
BUTTERFIELD ROAD ILLINOIS ROUTE 56
662'
675'
SUBJECT PROPERTY Area = 908,756 sf
1124' = 20.86 Ac.
ALBRIGHT STREET
479'
ILLINOIS ROUTE 59
332'
440'
165'
660' NOTE: ESTES STREET Boundary and parcel lines shown are courtesy of Du Page County GIS. Aerial image is from Google Earth. Date of photography: April 30, 2015.
Project Mgr.: T A J HAEGER ENGINEERING AERIAL PROPERTY EXHIBIT Engineer: L A K consulting engineers land surveyors Date: 2017.05.31 100 East State Parkway, Schaumburg, Illinois 60173-5300 NORTH LEXINGTON TRACE Project No. 16-118 Tel: 847.394.6600 Fax: 847.394.6608 0 160 Illinois Professional Design Firm License No. 184-003152 PRELIMINARY PUD PLAT SUBMITTAL Sheet www.haegerengineering.com No. Date Revision Scale: 1" = 160' CITY OF WARRENVILLE, DuPAGE COUNTY, ILLINOIS
Plot Date: May 24, 2017 - 4:44pm Plotted By: tom-j File Name: P:\2016\16118\Drawings\Preliminary\16118-Tabloid Exhibits.dwg C 2017 Haeger Engineering, LLC BUTTERFIELD ROAD ILLINOIS ROUTE 56
Freshwater Emergent Wetland
Freshwater Forested/ Shrub Wetland
BRIGGS AVENUE SUBJECT PROPERTY
ALBRIGHT STREET Freshwater Emergent Wetland
ILLINOIS ROUTE 59
Freshwater Forested/ Shrub Wetland ESTES STREET
NOTE: Boundary and parcel lines shown are courtesy of Du Page County GIS. Aerial image is from Google Earth. Date of photography: April 30, 2015.
Project Mgr.: T A J HAEGER ENGINEERING DuPAGE COUNTY WETLANDS EXHIBIT Engineer: L A K consulting engineers land surveyors Date: 2017.05.31 100 East State Parkway, Schaumburg, Illinois 60173-5300 NORTH LEXINGTON TRACE Project No. 16-118 Tel: 847.394.6600 Fax: 847.394.6608 0 200 Illinois Professional Design Firm License No. 184-003152 PRELIMINARY PUD PLAT SUBMITTAL Sheet www.haegerengineering.com No. Date Revision Scale: 1" = 200' CITY OF WARRENVILLE, DuPAGE COUNTY, ILLINOIS
Plot Date: May 24, 2017 - 4:45pm Plotted By: tom-j File Name: P:\2016\16118\Drawings\Preliminary\16118-Tabloid Exhibits.dwg C 2017 Haeger Engineering, LLC BRIGGS AVENUE
SUBJECT PROPERTY
ILLINOIS ROUTE 59
ESTES STREET
Project Mgr.: T A J HAEGER ENGINEERING FEMA FIRM EXHIBIT Engineer: L A K consulting engineers land surveyors Date: 2017.05.31 100 East State Parkway, Schaumburg, Illinois 60173-5300 NORTH LEXINGTON TRACE Project No. 16-118 Tel: 847.394.6600 Fax: 847.394.6608 0 200 Illinois Professional Design Firm License No. 184-003152 PRELIMINARY PUD PLAT SUBMITTAL Sheet www.haegerengineering.com No. Date Revision Scale: 1" = 200' CITY OF WARRENVILLE, DuPAGE COUNTY, ILLINOIS
Plot Date: May 24, 2017 - 4:46pm Plotted By: tom-j File Name: P:\2016\16118\Drawings\Preliminary\16118-Tabloid Exhibits.dwg C 2017 Haeger Engineering, LLC 3
CHURCH PARCEL DETENTION PLANS
• Emmanuel Baptist Detention Plan • Emmanuel Baptist Detention Plan – As-Built • Blanchard Alliance Detention Plan – As-Built
NORTH 40 0 80
Scale: 1" = 80'
Original Print Size: 24"x36"
Ex 36" FES Inv 710.78
716.50 10" Clay Tile Outfall 711.87
Flow is Restricted by 10" Pipe Overflow at Elevation 716.50
732.25 AREA 3 Ex Culvert Ex MH 11.519 ACRES Inv. 713.36 (12") Rim 717.86 CN = 79.7 Inv 711.76 (10" VCP E) Inv 712.81 (12" RCP S) HWL = 716.57 729.75 Inv 713.21 (12" RCP W) 6.027 Ac-FT Wetland "A" (Gentile Wetland) AREA 4 Existing Culvert 2.919 ACRES under Briggs Street CN = 88.3 HWL = 728.19 Wetland "C" 724.44 1.095 AC-FT 724.68 716.30
Area 4 Modeled Per Blanchard Alliance 718.30 Church As-Built Plans Dated 04/20/2012
AREA 5 Time of Concentration Path (Typ.) Ex CB 2.308 ACRES Gr. 717.64 CN = 83.3 Q-PEAK = 13.20 CFS Revision 726.00 Ex MH Rim 718.99 729.00 Inv 713.49 (12" N) Date Modeled as a Micro-Pond 718.20 12" Sewer 721.75 No. Rim 721.16 721.25 Inv. 715.51 721.50 721.84 723.00
725.25 12" RCP
725.50 Wetland "B" Ex CB (2' Ø)
Gr. 719.83 land surveyors
Ex FES SUBAREA 1-2 SUBAREA 1-1 Inv. 716.43 (5") 3.664 ACRES AREA 2 19.750 ACRES 10.904 ACRES CN = 82.7 HWL = 718.45
2.105 AC-FT www.haegerengineering.com AREA 1 23.413 ACRES CN = 83.3 HWL = 721.05
Drainage Boundary (Typ.) 717.67 Illinois Professional Design Firm License No. 184-003152 7.408 AC-FT 721.10 HAEGER ENGINEERING 100 East State Parkway, Schaumburg, IL 60173 Tel: 847.394.6600 Fax: 847.394.6608 consulting engineers 720.83
1' Contours per Topo Survey (Typ.) WARRENVILLE, ILLINOIS LEXINGTON TRACE DRAINAGE EXHIBIT EXISTING CONDITIONS PRELIMINARY PUD SUBMITTAL 2' Contours per DuPage County GIS (Typ.)
Project Manager: L A K Engineer: D J V Date: 07/12/2017 Project No. 16-118 Sheet 1 2 2017 Haeger Engineering, LLC C Plot Date: Jul 12, 2017 - 8:35am Plotted By: tom-j File Name: P:\2016\16118\Drawings\Exhibits\16118-Drainage Exhbt_Exist.dwg NORTH 30 0 60
Scale: 1" = 60'
Original Print Size: 24"x36"
726 725
723 E
722
U
N 721
E
724 720 V
A 719 WETLAND "A" (Gentile Wetland) Y
E 724 L
K 724
R
A
B 0.024 ACRE 723 0.075 ACRE WETLAND IMPACT WETLAND IMPACT
WETLAND "C" 723 723 1.81 AC-FT COMP.
717 STORAGE VOLUME
716
718
722 718 719 719 716 714 718 719 717 716 715 722 715 714 719 COMPENSATORY FLOOD STORAGE 714 716 722 & CREATED WETLAND 720 Church Pond Outfall w/ Meandering Channels Gross Area = 0.84 AC. Net Area = 0.64 AC. 717 Pond "B" Secondary Overflow 11.16 ACRES TRIBUTARY TO at Elevation 721.00 POND "A" 715 721 718
719
722 DETENTION POND 'A' 716 723
719 V = 4.54 AC-FT HWL = 718.00 722 NWL = 714.00 722 723 Bot. = 713.0±
723 Wetland Type Basin
w/ Meandering Channel 717 723 2.08 ACRES 719 TRIBUTARY TO POND "B" 723 718 716 Pond "B" Revision DETENTION Primary Overflow POND 'B' V = 0.91 AC-FT at Elevation 720.00 HWL = 720.00 NWL = 716.00 722
Wetland Type Basin Date w/ Meandering Channel
714 719 717 715 721 716 717 No.
723 718
722 719 721 720 718 721 722 723 724
723 725 721
719 723
720 WETLAND "B" 723
722 723 EXISTING WETLAND / 722 DEPRESSIONAL STORAGE 722 HWL = 718.45
721 722 Wetland Flow Routes
to Detention Pond "A" land surveyors 718 722 720 719 720
721 721 PRE-TREATMENT BASIN 'C' 720 HWL = 719.50 ENHANCED WETLAND AREA 720 720 723 CHURCH OVERFLOW ROUTE 719 NWL = 717.50 723 Bot. = 716.5± 719PRE-TREATMENT 718 BASIN 'B' 718 717 721 HWL = 719.50 721 720 NWL = 717.50 720 719 717 718 Bot. = 716.5± 725 718 722 724 PRE-TREATMENT 723 719 722 BASIN 'A' 723 720 www.haegerengineering.com
723 722
722 722 721 STREET 'B'
723
Illinois Professional Design Firm License No. 184-003152 720 722
723 723 723 724 721
724 HAEGER ENGINEERING 725 725 Church Pond Overflow at Elevation 721.10 100 East State Parkway, Schaumburg, IL 60173 Tel: 847.394.6600 Fax: 847.394.6608
726 consulting engineers
OVERFLOW AREA FILL720 721
722 722 720 726
723
721 723
723
721
722 724
724 725
721
723 723 726 725
725
723 722 721 725
724
723 722
722 721 723
724
726 723
724
721 724 STREET 'A' 725 721 2.50 ACRES TRIBUTARY TO 725 716 726 723 722 POND "C" 727 722 721 724
BARKLEY AVENUE 721 724 722 723 725
717
724 724
718 723 DETENTION POND 'C' 724 V = 1.02 AC-FT 719 HWL = 720.00 WETLAND "B" FILL
NWL = 716.00 720
723 Wetland Type Basin 721 (1.488 Ac-ft Comp.
w/ Meandering Channel 722 721 723 722 Storage & 0.533 Ac 723 WARRENVILLE, ILLINOIS
722 Wetland Impact)
723 724 723
725 LEXINGTON TRACE DRAINAGE EXHIBIT
726
727 PROPOSED CONDITIONS
727 PRELIMINARY PUD SUBMITTAL 726 724 725 721 728 722
Project Manager: L A K Engineer: D J V Date: 7/12/2017 Project No. 16-118 Sheet 2 2 2017 Haeger Engineering, LLC C Plot Date: Jul 12, 2017 - 8:36am Plotted By: tom-j File Name: P:\2016\16118\Drawings\Exhibits\16118-Drainage Exhbt_Prop.dwg