Loading...
HomeMy WebLinkAboutV. COW Agenda Item Lake Briarwood Sanitary Sewer System Evaluation Mount Pros • Mount Prospect Public Works Department INTEROFFICE MEMORANDUM TO: VILLAGE MANAGER MICHAEL E. JANONIS FROM: DEPUTY DIRECTOR OF PUBLIC WORKS DATE: SEPTEMBER 22, 2010 SUBJ: LAKE BRIARWOOD BASIN 37 SANITARY SEWER INVESTIGATION FINAL REPORT Background Late last year (2009), several residents from the Lake Briarwood residential subdivision contacted staff to express concerns about the frequency and voracity of basement back -ups in their neighborhood. Of particular concern to staff were complaints about basement back -ups that occurred during dry- weather periods as well as complaints from homeowners that have endured back -ups more than once. Coincidentally, for most of 2009, staff had worked with Community Development Department Environmental Health Division inspectors and business owners in the Briarwood Plaza shopping center to reduce the volume of fats, oils and grease (FOG) entering the Village -owed sanitary sewer system that serves both the Briarwood Plaza businesses and the Lake Briarwood homes. At that time, several of the businesses in the Briarwood Plaza were restaurants or retail food purveyors that produced grease as a by- product of food preparation. For much of 2008 and 2009, Public Works crews had observed substantial accumulations of grease in the sewers near the Briarwood Plaza point of connection with the Village -owned sewer main. However, by late 2009, it appeared that robust inspections by Community Development Department inspectors along with the diligent efforts by Public Works crews, including the addition of grease - eating chemical additives; frequent flushing; and almost daily inspections had greatly reduced the presence of grease in Briarwood -area sewers. Unfortunately, the perceived success of staff's efforts did not match the reality related by Lake Briarwood homeowners. Subsequently, staff concluded that more complex issues were at play and that it was necessary to conduct a comprehensive sanitary sewer evaluation study (SSES) in order to identify the factors that were causing the sewer system to function so poorly. In January 2010, the Village Board awarded a contract to Baxter and Woodman consulting engineers of Crystal Lake, Illinois to perform an SSES of the entire Lake Briarwood area sanitary sewer basin. A basin is a network of properties and sewer pipes that share a common connection to a Metropolitan Water Reclamation District of Greater Chicago (MWRDGC) interceptor sewer. Internally, staff refers to the Lake Briarwood area basin as Basin 37. In general, Basin 37 flows from the north to the south and includes multi - family properties (such as Algonquin Trails Apartments), single - family homes (such as Lake Briarwood), and commercial properties (such as Briarwood Plaza). Page 2 of 2 Lake Briarwood Basin 37 Sanitary Sewer Investigation Final Report September 22, 2010 Ultimately, Basin 37 discharges to an MWRDGC interceptor on the west side of Busse Road just north of the 1 -90 overpass. Baxter and Woodman was specifically tasked with analyzing performance data collected from Basin 37, modeling the sewer system, identifying causes of poor performance, and recommending corrective actions. In conjunction with this effort, Public Works staff inspected the sewers with closed - circuit cameras, inspected manholes, installed flow monitors to establish dry- weather and wet - weather performance metrics, and inspected every structure (including all single - family and multi - family buildings) tributary to Basin 37. All of this data was included in Baxter and Woodman's analysis of the system. Final Report Attached for your review and consideration is an executive summary of the final report prepared by Baxter and Woodman. A copy of the full report is also available for review on the Village website (www.mountprospect.orq). In summary, the report identifies a number of both private sector and public sector defects that contribute to the substandard performance of Basin 37. The report also outlines several corrective actions that are necessary to alleviate the area's basement back -up and sewer surcharging problems. For your reference, staff has taken the liberty of including the suggested public sector improvements in the 2011 proposed budget and 2012 budget forecast. Representatives from Baxter and Woodman, along with appropriate Village staff, will be on hand to present this report and its findings to the Village Board at the September 28 Committee of the Whole meeting. With the Village Board's concurrence, a subsequent neighborhood meeting will be scheduled to present same to Basin 37 sanitary sewer customers. EXECUTIVE SUMMARY With the authorization of the Village of Mount Prospect, Baxter & Woodman (B &W) completed this Sanitary Sewer Investigation to determine the causes of sewer surcharging that lead to basement backups and other operational problems within a portion of Basin 37. The investigation included a sanitary sewer capacity analysis, review of internal sewer television inspection videos, flow monitoring, building -to- building canvassing and smoke testing to identify I/I sources. The following is a summary of the findings, conclusions and recommendations of this investigation. 1. A sanitary sewer capacity analysis of the trunk sewer, generally extending along Briarwood Drive East and Lynn Court, was conducted to determine its flowing full capacity. Topographical survey data collected at each manhole showed some individual sections of sewer were constructed at less than the recommended minimum slope, but the slope of the trunk sewer as a whole should allow for enough capacity to serve the tributary area. However, there are two sections of sewer downstream of Lynn Court that are actually back pitched, or sloped in the wrong direction. 2. Review of sanitary sewer televising videos was performed to determine the condition of the mainline sewers and service connections. Several sections of sewer were found to be in poor condition, including pipe cracks, root intrusion and offset joints. The defective sewer sections are generally located near the south end of Briarwood Drive East, along Lynn Court, and east toward South Busse Road. Additionally, numerous sags were identified in the trunk sewer. Sags are dips in the sewer that significantly reduce the carrying capacity of a sewer. The sewer sections that contain the most significant sags are located near the north end of Briarwood Drive East. In this area, sewer surcharging exists even during dry- weather conditions. One of the most significant problems identified in the trunk sewer is, however, the amount of grease build -up in the pipes. Grease discharged into the sanitary sewer is not only a concern from restaurants and food processing facilities, but can also be problematic from cooking operations in residential areas. Grease tends to harden and accumulate around the top of a sewer which significantly reduces the amount of cross - sectional area available for transporting flow. Heavy grease build -up was identified along the entire length of the trunk sewer, particularly upstream of the commercial establishments, immediately downstream of the apartments north of Algonquin Road. 091241.30 - 09/10 2. 3. Flow monitoring was conducted at key locations along the trunk sewer. The purpose of flow monitoring is to determine the amount of I/1 (storm water /groundwater) that enters the system during wet - weather events, and to determine the hydraulic conditions that occur when the flows in the sewers increase. A moderate rain event that occurred during the monitoring period caused significant surcharging near the south ends of Briarwood Drive East, Briarwood Drive West and along Lynn Court. The cause of the surcharging is a result of excessive I /1. 4. Building canvassing identified 40 illegally connected storm sump pumps. This represents approximately 15 percent of the units visited. Based on a typical sump pump discharge rate of 20 to 30 gallons per minute (gpm), it is estimated that up to 1,200 gpm of I/I is contributed to the sewer system by these sources during a sustained rainstorm. This quantity of flow alone is many times greater than the capacity of the sewers serving the area. The sump pump discharge piping should be disconnected from the sanitary sewer system and re- routed to discharge to grade. 5. Smoke testing identified one connected downspout, which would contribute 10 to 20 gpm of I/I into the sanitary sewer system during a sustained rain storm. Possible broken building laterals and connected foundation drains were also identified, but because these sources are buried and, therefore, inaccessible, I/1 rates could not be estimated. Of greater concern were 36 properties that did not emit smoke from building vent stacks. This was most likely caused by sags in the mainline sewer which did not allow smoke to pass to the home. Therefore, any stormwater drains that connect to the sanitary sewer on these properties could not be detected. 6. The recommended improvements from this investigation are separated into two phases as follows: Phase 1 a. Replace approximately 720 feet of sewer near the north ends of Briarwood Drive East and West from MHs 37S01 to 37S05 to eliminate pipe defects and sags. The estimated construction cost for this work is $180,000. b. Replace approximately 940 feet of sewer generally located along Lynn Court from MHs 37S12 to 38S52 to eliminate pipe defects and provide a consistent sewer slope. The estimate construction cost for this work is $258,500. c. Rehabilitate approximately 790 feet of sewer along Briarwood Drive West from MHs 37S09 to 37S12 using cured -in -place pipe (CIPP) to eliminate pipe defects. The estimated construction cost for this work is $31,600. 091241.30 - 09/10 3. d. Enforce disconnection of stormwater sources located on private property including sump pumps and downspouts. e. Conduct a public education program to make all system users aware of the importance of keeping all grease out of the sanitary sewer system by disposing these materials in the trash rather than pouring them down the drain. We also recommend the Village create a fats, oils and grease (FOG) ordinance that pertains to all system users. Phase 2 a. Replace approximately 900 feet of sewer along Briarwood Drive West from MHs 37S05 to 37S09 to eliminate pipe sags. This portion of the sewer has previously been lined and does not contain any defects that allow I/I to enter. However, numerous sags throughout these sections reduce the carrying capacity of the sewer. Although these sags are not as significant as in the sections that are recommended for replacement in Phase 1, the Village may wish to replace this portion in the future to maximize the flowing full capacity of the trunk sewer. The estimated construction cost for this work is $225,000. 091241.30 - 09/10 1 -1 1. INTRODUCTION 1.1 General The Village of Mount Prospect has historically experienced periodic operational problems with sanitary sewers located within Basin 37. This portion of the Village's sanitary sewer system is generally bounded by South Busse Road on the east, Interstate 90 on the south, Briarwood Drive West on the west and Algonquin Road on the north, with a small portion extending north of Algonquin Road. A detailed map of Basin 37, provided by the Village of Mount Prospect, is shown in Exhibit A. On occasion, basement backup complaints have been filed by some of the homeowners in the Briarwood Subdivision, which is included in Basin 37. Most of these complaints are from homeowners living near the intersection of Briarwood Drive West, Briarwood Drive East and Briarwood Drive. Upon investigating these complaints, the Village's Public Works staff have determined that the backups are primarily caused by blockages in the sanitary sewers due to grease build -up, with infiltration and inflow (I /I) also being a potential cause. The accumulation of grease displaces the cross sectional areas of the sewers and results in a significant reduction in conveyance capacity. Public Works staff spend a considerable amount of time adding chemicals and /or jetting the sewers to remove or prevent blockages from occurring on a routine basis. 1.2 Study Scope and Methodology This study was commissioned to investigate all potential factors that cause the sewers in Basin 37 to surcharge, and to provide recommendations to eliminate or significantly 091241.30 - 09/10 1 -2 reduce these issues. This investigation consisted of several investigative tasks to determine the causes of the sanitary sewer surcharging, which are summarized below. 1.2.1 Sanitary Sewer Capacity Analysis - A topographical survey was conducted of all 45 public sanitary sewer manholes within the study area. Specifically, the data collected included the spacial coordinates of each manhole and elevations of the manhole rims and pipe inverts. Part of the data collected was used to determine the flowing full capacity of the trunk sewer serving Basin 37. For the purposes of this investigation, the trunk sewer is considered as the line extending from MH 31 S25 south to MH 37S03, then along Briarwood Drive East to MH 37S12, along Lynn Court to MH 37S16, then east to the Metropolitan Water Reclamation District of Greater Chicago (MWRDGC) sewer on South Busse Road (see Exhibit A). The Chezy- Manning equation was used to determine the flowing full capacity of each sewer segment based on pipe size, length and slope. 1.2.2 Internal Sewer Television Inspection Review - A sewer television inspection allows for a detailed structural evaluation of the sewers and building connections. The trunk sewer was televised by Public Works staff using a closed circuit television camera. The sewer sections were first cleaned to remove loose debris and grease using a high pressure water jetting process to enable proper viewing of the sewer. The locations of all building laterals, pipe defects, root intrusions, mineral deposits, grease accumulation and I/I sources were identified. 1.2.3 Flow Monitoring Data Analysis - Five in -line flow meters were installed in key locations along the trunk sewer to measure flows during dry and wet weather periods. The flow monitoring equipment used were Sigma Portable Area Velocity Flow Meters 091241.30 - 09/10 1 -3 manufactured by the Hach Company. The meters consist of a small area - velocity probe attached to a circular bracket that is placed directly in the sewer pipe. The probe uses an ultrasonic Doppler signal to measure the average flow velocity and a pressure transducer to measure the flow depth. The probe accurately measures the flow depth and velocity during periods of normal open channel flow conditions as well as during surcharge conditions when the water level is above the top of the sewer pipe. The data is transmitted through a cable to the unit's electronic module, which is mounted near the top of the manhole. The logged data is retrieved using a portable computer containing the manufacturer's software for converting the velocity and depth readings to a flow rate based on the sewer diameter. The flow monitoring work was conducted by Elan Industries. They provided the flow monitoring equipment needed as well as an electronic rain gage to measure rainfall during wet weather events. The flow data was analyzed by Baxter & Woodman using a computer software program developed by the flow meter manufacturer that allows the data to be viewed in both tabular and graphical format. Further analysis was performed by exporting the data to Excel spreadsheets developed by Baxter & Woodman. This analysis calculates average daily dry- weather flow rates (ADDWF), peak wet weather flow rates (PWWF), I/I flow rates, as well as several other parameters. Figure 1 shows a typical diurnal flow fluctuation during an average dry- weather day. 091241.30 - 09/10 1 -4 FIGURE 1 Typical Diurnal Flow Fluctuation S0 J 3 till at. . 40 ... << ADDWF- Weekday 40 + ADDWF- "' Weekend 1 0 F i w+ 0.00 4.00 8.00 12.00 16.1)0 0:00 Time of Day Dry weather flow consists of normal daily sewage production plus base infiltration. Infiltration is groundwater entering the sewer system through sources such as open joints between sections of pipe, cracks in the mainline sewer and building lateral pipes, connected foundation footing drains, and leaking manholes. In many sanitary sewer systems, infiltration is present even during dry weather periods. The amount of infiltration in the sewer system is dependent on groundwater level. Typically, groundwater levels are highest in late winter and early spring as snowmelt percolates through the ground. During this time, defects in pipes and manholes can allow groundwater to continuously enter the sanitary sewer system. This extraneous water is commonly referred to as baseline infiltration. 091241.30 — 09/10 1 -5 Inflow is stormwater runoff discharged into the sanitary sewer system from sources such as roof downspouts, area drains, foundation drains, open pickholes in manhole covers, storm sump pumps and cross connections from the storm sewer system. Typically, when a rainstorm begins, inflow is the dominant component of I /I. As the storm progresses, water percolating through the ground raises the groundwater level and allows water to infiltrate into sewers through defects as previously discussed. Since this process takes some time to occur, the resulting impact on sanitary sewer flows is generally delayed, but can continue for an extended period of time after the storm event ends. This component of I/I is commonly referred to as rainfall- induced infiltration. ADDWF was determined by averaging total daily flow at each monitoring location during several dry weather days. A dry weather day is defined as a day preceded by at least three days with no precipitation. For the selected dry weather days, flow rates for each one - hour time interval were averaged to obtain a "typical" dry day flow hydrograph. Using average one -hour data intervals accounts for fluctuations in water usage (and the resulting wastewater flows) throughout the day. For the selected wet weather events, I/I rates were calculated by subtracting dry weather flow rates from corresponding wet weather flow rates at the same time during the day. 1.2.4 Building -to- Building Canvassing - Building -to- building canvassing was conducted by Public Works staff. This work consists of entering private property to identify the discharge points for all building downspouts outside the home, any apparent area drains and the discharge location of any storm sump pumps inside the houses. Any of these 091241.30 - 09/10 1 -6 sources, if connected to the sanitary sewer system, can have a significant impact on wet weather flows. 1.2.5 Smoke Testing - Smoke testing is used to identify defects and inappropriate connections in both mainline sewers and building lateral connections. Of particular significance is the ability to identify connections that allow stormwater to directly enter the sanitary sewer system, which can cause immediate and significant increases in flow. These sources include building downspouts, window well drains, area drains, foundation drains and connections to the storm sewer system. The testing consists of injecting a non -toxic chemical smoke under pressure into the sewer system using a high capacity blower. During the test, all smoke emission points are noted and recorded in field reports. It is expected that the smoke will be discharged at locations such as building vent stacks and adjacent sanitary sewer manhole covers. Other emission points, such as storm sewer inlets and storm sewer manholes, indicate where smoke transfers from the sanitary sewer system directly to the storm sewer system. This suggests that stormwater may also transfer from the storm sewers to the sanitary sewers during wet weather. All inappropriate smoke emission points identified were digitally photographed and the pictures are included with a digital version of this report. 091241.30 - 09/10 2 -1 2. FIELD INVESTIGATION AND RESULTS 2.1 Sanitary Sewer Capacity Analysis Topographical survey data was collected for the 45 public sanitary sewer manholes within the study area. A portion of the data was used to calculate the flowing full capacity of the trunk sewer using the spacial data (x and y- coordinates) to determine the lengths of sewer between manholes along with the pipe invert elevations to determine sewer slopes. A complete list of all data collected for each manhole is included in Appendix A. The Chezy- Manning equation was used to determine the sewer capacities based on pipe size, length and slope. Table 1 shows the results of this analysis, listed from upstream to downstream along the length of the trunk sewer. 091241.30 - 09/10 2 -2 TABLE 1 Sanitary Sewer Capacities Pipe Max Flow Max Flow Manhole Reach Pipe Section Pipe Based on Based on Size Length Slope Pipe Slope Avg. Pipe To From (inches) (feet) ( %) (gpm) Slope (gpm) 31S25 31S26 12 217 1.080 1,972 1,972 31S26 31S28 8 92 0.759 561 N/A 31S28 31S29 8 37 1.073 667 593 31S29 37S03 12 364 0.332 1,094 1,094 37S03 37SO4 8 195 0.210 295 N/A 37SO4 37S05 8 354 0.376 395 362 37S05 37S06 8 177 0.441 428 406 37S06 37S07 8 230 0.460 437 433 37S07 37S08 8 213 0.339 375 408 37S08 37S09 8 284 0.454 434 410 37S09 37S10 8 260 0.408 411 423 37s10 37S11 8 314 0.083 185 309 37S11 37S12 8 218 1.024 651 440 37S12 37S13 10 160 0.144 443 N/A 37S13 37S15 10 133 0.480 808 636 37S15 37S16 10 55 0.036 222 690 37S16 37S17 10 189 0.185 502 454 37S17 38S51 10 228 0.557 871 727 38S51 38S52 10 160 -0.094 N/A 627 38S52 38S53 10 95 0.443 777 380 38S53 38S54 10 284 0.331 672 700 38S54 38S72 10 28 -0.818 N/A 557 38S72 38S56 10 390 0.305 645 559 38S56 38S57 10 91 0.518 840 686 37S01 37S02 8 139 0.230 309 N/A 37S02 37S03 8 40 1.575 808 469 1 Negative slope indicates a back - pitched pipe (pipe slopes upward from upstream to downstream). 2 Flow rates cannot be accurately estimated for back - pitched pipes. 091241.30 - 09/10 2 -3 As the table shows, the individual pipe slopes are not uniform from section to section. This creates a disparity in the flowing full capacity throughout the trunk sewer. With this condition, as the flow in a sewer increases and nears its full capacity, the profile of the water surface changes from the individual pipe slope to the average of several pipes together. For this reason, it is more reasonable to calculate the flowing full capacity of the trunk sewer based on the average pipe slope of two adjacent sewers rather than on an individual basis as shown in the last column of the table. Sanitary sewers are designed with minimum slope requirements. This allows the flow in the sewer to move at a rate which keeps solids from settling out of the flow. Minimum slopes for the pipe sizes evaluated in this study are as follows: 0.40 percent for an 8 -inch diameter sewer, 0.28 percent for a 10 -inch diameter sewer and 0.22 percent for a 12- inch diameter sewer. For sewers that are constructed at less than the minimum slope, there is a higher likelihood of accumulation of debris, which can significantly decrease the conveyance capacity of the sewer, and in extreme cases, cause a sewer blockage. As Table 1 shows, many of the sewer sections along the trunk sewer were constructed at less than the specified minimum slopes, and some pipe sections even have negative slopes (pipe slopes upward from upstream to downstream). A visual observation of MH 37S03 during an extended dry weather period revealed that the normal top of the water surface appears to always be above the crown of the downstream sewer. The flow in this manhole appears to be stagnant during normal dry- weather flow conditions with a layer of grease floating on top. This condition is not apparent from the survey data since the sewer slope from MH 37S03 to MH 37SO4 is positive, 091241.30 - 09/10 2 -4 although less than minimum slope for an 8 -inch diameter pipe (0.21 percent actual slope as compared to recommended minimum slope of 0.40 percent). As will be discussed later in this report, the television inspection review revealed that this section of the trunk sewer, and in fact most of the trunk sewer along Briarwood Drive East, contains numerous sags that significantly affect the conveyance capacity. Flow volume is a direct function of the flow velocity and the cross - sectional area of the flow at any point. If sags are present in a pipe, the flow depth (cross - sectional area) changes throughout the length of that pipe. Therefore, for the same amount of flow, as the depth increases, the velocity decreases and vice - versa. Where sags are present, the flow depth increases which results in a decrease in the velocity. In many cases, this is where debris accumulates, and in the case of Basin 37, grease accumulates as well. This appears to be the cause of the surcharged condition in MH 37S03. Immediately downstream of this manhole, a significant sag exists which causes this section of the sewer to always be full. With a full pipe and relatively little flow from the upstream area, a significant amount of debris and grease accumulate at this location and periodically causes a complete blockage. The two sewer sections included at the bottom of the table between Manholes 37S01 and 37S03 are not part of the trunk sewer, but the data is included since some of the homeowners connected to this portion of the sewer experience basement backups. The pipe slope between Manholes 37S01 to 37S02 is less than the minimum. This condition is made worse by the normal high water level in the downstream Manhole 37S03. Table 1 also shows there are two sections of the sewer that are actually back - pitched or sloped in the wrong direction (rising slope from upstream to downstream). This not only 091241.30 - 09/10 2 -5 has a negative impact on the conveyance capacity of a sewer, but it also allows solids and grease to settle out of the flow. 2.2 Internal Sewer Television Inspection Review The television inspection work was performed by the Village of Mount Prospect's Public Works staff, and the videos were reviewed and analyzed by Baxter & Woodman. Approximately 4,800 feet of sanitary sewer was televised along the trunk sewer. A summary of defects identified during the television inspection are shown in Table 2. TABLE 2 Defects Identified During Television Inspection Manhole Reach Pipe From To Size, in. Defects 37S01 37S02 8 Heavy roots, shattered /missing pipe (58'- 61') 37S02 37S03 8 Shattered pipe, completely full with water 37S03 37S09 8 Lined pipe but contains significant sags 37S09 37S10 8 Heavy root intrusion throughout 37510 37511 8 Severe pipe cracks (218' 240') 37511 37S12 8 Cracked pipe (0' -10', 38' -40', 77' -78', 130'), heavy roots 37S13 37S15 10 Cracked pipe (128'- 132'), infiltration 37S15 37S16 10 Cracked pipe (0' -5', 15' -18'), protruding lateral (17') 37S16 37S17 10 Shattered pipe (75' — 80'), offset joints throughout 37517 38551 10 Cracked pipe (90' -94', 223'- 226'), offset joints throughout 38S51 38S52 10 Cracked pipe (101' -103') The television inspection logs for each sewer section televised are included in Appendix B. Exhibit A, provided by the Village of Mount Prospect, shows the materials of construction of each sewer section. The portion between Manholes 37S03 and 37S09 along Briarwood Drive East has been previously lined and is in good structural condition. However, there are numerous sags throughout which appear to keep this pipe section full of 091241.30 - 09/10 2 -6 sewage even during dry weather conditions. During the televising work, the jet hose was needed immediately in front of the camera throughout this entire section to pull the water level down so the pipe could be viewed. It was noted that the entire length of the trunk sewer showed signs of heavy grease build -up. According to Public Works staff, the restaurants located at the corner of Briarwood Drive North and Algonquin Road have grease traps per Village Code. These restaurants discharge their flow to the sewer section between Manholes 37S03 and 37SO4. Since heavy grease buildup was observed upstream of these connections, specifically between Manholes 31S25 and 31 S26, it is apparent that the multi- family units north of Algonquin Road are heavy contributors to the problem. The recommended rehabilitation method for the trunk sewer is a combination of cured -in -place pipe (CIPP) and excavation/replacement. The recommended method for each specific repair location is discussed later in this report along with expected rehabilitation costs. 2.3 Flow Monitoring Data Analysis Elan Industries was contracted to conduct the flow monitoring work, and Baxter & Woodman interpreted and analyzed the flow monitoring data. Five flow meters were installed on April 13, 2010 and removed on May 19, 2010. Flow meters were installed at varying locations throughout Basin 37 to determine probable sources of I/I and locate flow restrictions. Appendix C shows the flow monitoring locations. During the monitoring period, two rainstorms occurred that provided sufficient data for calculating I /I. Table 3 lists the details of each rainfall event. 091241.30-09/10 2 -7 TABLE 3 Rainfall Data Dates Rainfall Total (inches) Rainfall Duration (hours) May 2, 2010 1.15 6 May 13, 2010 1.99 12 The objective of flow monitoring is to determine the hydraulic conditions that occur during moderate to large wet weather events. At several of the monitoring manholes, a sewer surcharge condition was experienced during the larger May 13 storm. There are two primary reasons that a sewer will surcharge: either the amount of flow is greater than the flowing full capacity of the sewer, or a downstream restriction exists. In the former case, the solution typically is to remove excessive I /I. In the latter case, a solution may be to identify and remove the "bottleneck ". A downstream restriction may be caused by roots, a large object or other debris, a defective pipe, or simply an undersized section of sewer that cannot transport all of the tributary flow. As flows increase and the flow depth reaches the top of a pipe and begins to surcharge, the change in the velocity can provide an indication of potential causes. If the velocity continues to increase along with the depth, the surcharging is a result of excessive I/I upstream and not a downstream restriction. Conversely, if the velocity decreases or stops, a downstream condition exists that restricts the flowing full capacity of the sewer. Table 4 shows the dry weather flows along with the wet weather conditions that were experienced as a result of the May 13 rain event at each monitoring location. Appendix D includes a summary of water level, velocity and flow data from all rain events, as well as a graphical comparison to baseline flow data. 091241.30 - 09/10 2 -8 TABLE 4 Flow Data from May 13, 2010 Rain Event Monitoring Pipe ADDWF Peak 1 -hr. Maximum Peak 1 -hr. Velocity Manhole Size (in) (gpm) Flow (gpm) Depth (in)* 111 ratio Change 31S29 8 19 57 2.6 3.36 Increase 37S05 8 24 112 3.6 4.24 Increase 37S11 8 46 233 55.1 6.10 Decrease 37S20 10 6 263 53.5 53.53 Decrease 38S57 10 153 1,177 11.9 8.27 Increase * Bold numbers indicate surcharged conditions. As the table shows, significant surcharging occurred at three of the five monitoring manholes during the May 13 rain event. Of the three surcharged manholes, Manholes 37511 and 37S20 experienced a decrease in flow velocity, indicating a downstream restriction. In these cases, the peak 1 -hour flows and I/I ratios may be artificially low since the flows were backing up. At each of the other manholes where representative data was collected, the velocities increased. A detailed discussion of the results at each of the monitoring manholes is included below. Manhole 31S29: This monitoring location was selected to determine peak flow conditions from the apartment complex at the far north (upstream) end of Basin 37 (north of Algonquin Road). The 8 -inch diameter sewer serves seven multi - family housing complexes, and averages only 19 gpm throughout the day during dry weather conditions. During the May 13 rain event, the peak flow was 57 gpm and the flow depth never exceeded one -half of the pipe diameter. Therefore, the amount of I/I at this monitoring location appears to be within acceptable limits. Manhole 37S05: This monitoring location is on Briarwood Drive East, and is located immediately south (downstream) of the restaurants in the Briarwood Plaza shopping center. This location was chosen to determine if the shopping center is a significant I/I 091241.30 - 09/10 2 -9 contributor. The 8 -inch diameter sewer serves a few more properties than at Manhole 31 S29, and, therefore, has a slightly higher average flow of 24 gpm throughout the day during dry weather conditions. During the May 13 rain event, the peak flow was 112 gpm and the flow depth never exceeded one -half of the pipe diameter. Therefore, the amount of I/I at this monitoring location appears to be within acceptable limits. Manhole 37S11: This monitoring location is at the south end of Briarwood Drive East, just upstream of the manhole where the trunk sewer converges with the sewer running along Briarwood Drive West. This location was selected to determine if the trunk sewer along Briarwood Drive East is a major contributor of I /I, and whether any flow restrictions may be present downstream. The ADDWF at this location is 46 gpm, while the peak flow during the May 13 rain event was 233 gpm. The I/I ratio for this pipe segment was 6.10, which is slightly higher than the I/I ratios at the upstream monitoring points. However, unlike the upstream monitoring locations, the velocity decreased as the flow depth increased. This indicates a lack of downstream capacity, likely in the 10 -inch diameter sewer that accepts flow from both the trunk sewer and the 8 -inch sewer running along Briarwood Drive West. It appears that the surcharging in this area is caused mostly by a lack of downstream sewer capacity, but is also partly due to I /I. Manhole 37S20: This monitoring location is at the south end of Briarwood Drive West, just upstream of the manhole where the 8 -inch sewer running along Briarwood Drive West converges with the trunk sewer. This location was selected to determine if the trunk sewer along Briarwood Drive West is a major contributor of I /I, and whether any flow restrictions are present downstream. The ADDWF at this location is only 6 gpm, but it had 091241.30 - 09/10 2 -10 the highest I/I ratio of all of the monitoring locations by a wide margin (ratio of 53.53 as compared to ratios of less than 10 at all other locations). The peak flow during the May 13 event was 263 gpm with a maximum flow depth of 53.5 inches in this 8 -inch diameter sewer. The velocity decreased with depth, indicating insufficient capacity in the 10 -inch diameter downstream sewer for moderate storm events due to a combination of excessive 1 /I, root intrusion, pipe sags and pipe slope. Manhole 38S57: This monitoring location is at the far downstream end of the 10- inch section of the trunk sewer, just before it discharges into an interceptor sewer owned by the MWRDGC. This location was selected to determine if the sewers serving the multi- family housing units at the south end of Basin 37 are a significant source of I /I, and whether flow restrictions are present along the 10 -inch diameter segment of the trunk sewer. During the May 13 rain event, the maximum depth in this 10 -inch diameter sewer was 11.9 inches (surcharged condition). However, unlike the two upstream monitoring locations, the velocity increased as the flow depth increased. This indicates that the downstream capacity in the MWRDGC interceptor sewer is sufficient. Therefore, it appears that the surcharging in this area is caused by a combination of excessive I/I and lack of capacity in the 10 -inch trunk sewer. 2.4 Building - to - Building Canvassing Building -to- building canvassing was conducted throughout Basin 37 by the Village's inspection contractor for the primary purpose of determining the discharge locations of all clear water (storm) sump pumps. Other information gathered included identifying area drains outside the building, footing drains, downspouts discharging below the ground surface 091241.30 - 09/10 2 -11 and history of sewer backup experiences. This work included 15 commercial properties, 118 single family residences and 126 multi - family units. 0 shows a blank copy of the inspection form used at each address. Of the properties surveyed, 40 were determined to have sump pumps discharging to the sanitary sewer, which could represent a significant portion of the wet weather flow detected during flow monitoring. During a rain storm when sumps pumps operate frequently, the 40 sump pumps could contribute up to 1,200 gpm of total inflow if they all operate simultaneously. This quantity of flow alone is many times greater than the capacity of the sewers. Table 5 is a summary of the results of the canvassing work. Appendix E includes the completed inspection forms for all of the addresses canvassed. Appendix F is a map showing the addresses that have confirmed or possible stormwater connections to the sanitary sewer. Appendix G is a map showing the addresses that filed a sewer back up compliant in 2010. TABLE 5 Canvassing Results Number Description of Units Commercial Properties 15 Single Family Properties 118 Multifamily Properties 126 Properties with Sewer Backup Complaints 43 Properties with Downspouts that Discharge Below Ground to Unknown Location 6 Properties with Outside Drains 97 Properties with Clear Water Sump Discharge to Sanitary Sewer 40 Properties with Clear Water Sump Discharge to Unknown Location 2 Properties with Suspected Footing Tile Connections 8 091241.30 - 09/10 2 -12 FIGURE 2 Blank Building Inspection Form Mount Prospect Public Works Department Inspection #: Inspection Date: Address: GENERAL 1. Property Type: Single Family Multi Family Commercial 2. Sanitary Plumbing Type: Gravity Overhead 3. Foundation Type: Basement Craw Space Slab 4. Has the property experienced a sewer backup? No Yes COMMERCIAL PROPERTY 5. Does the property have an inspection manhole? No Yes 6. Does the property dispose of fats, oils or grease dawn the drain? No Yes 7. Does the property have grease traps? No Yes 8. Does the property have any evidence of grease? No Yes 8a. If yes, describe location of grease: 9. Is there a log of grease trap cleanings within the last 90 days? No Yes DOWNSPOUTS 10. Are there any internal downspouts? No Yes 11. Are there above ground downspouts? No Yes 11a. Downspouts discharge less than 5 from foundation? No Yes 11b. Downspouts discharge more than 5 from property line? No Yes 12. Are there under ground downspouts? No Yes 12a. Are there visible discharge points? No Yes 12b. Popups or discharge points are less than 5 from foundation? No Yes 12c. Popups or discharge points are more than 5 from property line? No Yes OUTSIDE DRAINS 13. Does the property have outside drains? No Yes 13a. If outside drains exist record each type: Area Driveway Patio Stairwell Window well 14. Do all outside drains discharge overland? No Yes EJECTOR PUMP Printed on: 712712010 1 091241.30 — 09/10 1 2 -13 15 Dees the property have an ejector pump? No Yes 16. Is the ejector pt sealed) No Yes 1 7 Where does the ejector pump discharge) To ground T o sanitary Unknown Ct CA F Si�MP 18 Dees the property have a dearwater sump? No Yes 19 Are there any observable drain connections entering the dear water sump) No Yes 20 Where does the cleerwater sump dscharge? Sanitary Sewer Unknown To gourd less than 5' from tomdation To ground greater than 5' from foundation To ground less than 5` frorn property Tine To ground greater than 5' from properly line 21 Identify the type of drains entering the Clearwater crock: Floor drain Footing drain Laundry drain Other, identify 22 Is the bottom of the dearwater crock cpen? No Yes INSIDE PIPING, AND f H 0R DRAINS 23 Is there a direct connection between sanitary and dearweter piping) No Yes 24 Are there observable diverters) No Yes 25. Are there floor drains? No Yes 26. Where does the floor drain discharge) Gravity Sump punp Ejector punp RE Si II IS 21 Was a dye lest performed) No Yes 28 Was the dye lest positive? No Yes 29 Is there a suspected footing de connection? No Yes 30 Footing tile connection confirmed) No Yes COMMEN1 NOTIFICATION CHECKLIST Inso Notice Intro Notice: 2nd Appomtrnenl Request 2nd Appointment Request: 3rd Appointment Request 3rd Appointment Request Final Notice: Final Notice Red Tag Red Tag: WATER METER INFORMATION Water meter inst)led No Yes Installation Dale Serial tk Printed on 772712010 2 091241.30 — 09/10 2 -14 2.5 Smoke Testing Smoke testing is an effective method for identifying inflow sources such as building downspouts, window well drains, area drains, foundation drains and storm sewer cross connections to the sanitary sewer system. Smoke testing can also identify structural damage and leaking joints in the sewers and building laterals. The best results are obtained when the moisture content in the ground is minimal. This creates optimum conditions for smoke exiting a defective pipe section to pass through the overlying soil to the ground surface. The smoke testing was performed on July 27, 2010, during a dry weather period. Before initiating smoke testing, a notification letter was prepared by the Village of Mount Prospect and mailed to all addresses in the study area. The letter advised the residents of the upcoming smoke testing, reasons for conducting these tests, proper precautions to reduce the likelihood of smoke entering the building and what to do in the event smoke does enter the home. The precautions included pouring water into all seldom used drain traps, which blocks the smoke. The letter also stated that any person suffering from respiratory problems should contact the Public Works Department so they (the resident) could be notified immediately before testing began in their area. A copy of the notification letter is included in Appendix H. Smoke testing results are grouped into four categories according to the apparent type of defect. These categories are listed below, and the smoke testing results are detailed in Appendix I. Photos were taken at locations where smoke was observed to aid in the identification and location of the problems. An electronic version of the smoke testing results 091241.30 - 09/10 2 -15 spreadsheet with links to all of the photos is included on a CD, provided separately from this report. • Category A — Inappropriate sanitary sewer connections including downspouts, area drains and window well drains. • Category B — Probable broken building laterals, cracked or missing cleanout caps and connected foundation drains. Smoke is typically emitted from the ground surface near the lateral or the building foundation. • Category C — Probable plumbing problems, or sags in the mainline sewer or building lateral, which prevent smoke from passing. All buildings listed in this category had vent stacks that did not smoke during the testing. This problem does not contribute I/I to the system, but may mask sources that are upstream of a sag. • Category D — Sanitary manholes with smoke exiting from around the outside, through the ground. This condition does not necessarily indicate that the manhole is defective or allows I/I to enter. Due to the dry conditions experienced during smoke testing and the high pressure at which the smoke was injected, is not uncommon for smoke to escape the manhole through hairline cracks or through minute openings between adjusting rings or between the frame and corbel. Category A consists of sources that are on private property and directly connected to the sanitary sewer system. This category can include area drains, window well drains, building lateral cleanouts and downspouts that emitted smoke. One connected downspout was detected during smoke testing. Category B sources are all private property, which include defective building laterals that emitted smoke from the ground surface (typically resulting from a broken pipe or offset joint), smoke observed exiting from cleanouts with cracked or missing caps and smoke observed along building foundations. The latter case will almost always allow more I/I into the sewer system since smoke observed along the foundation may be from a connected footing drain. The function of this type of drain is to remove or reduce subsurface water 091241.30 -09/10 2 -16 around the building foundation. The effects from a moderate rainstorm, due to the sources in this category, can typically be seen shortly after the storm begins and may continue to contribute I/I long after the rain has stopped. There were ten such lateral and foundation drain defects found during smoke testing. Category C consists of buildings where the vent stack did not smoke. There were 36 such locations noted during the smoke testing. There are several possible reasons for smoke not exiting a building vent stack. The most likely causes are sags in the mainline sewers or service laterals that are filled with water (surcharged sewer), which were detected during manhole inspections and sewer televising. The surcharged conditions in the sewer would prevent smoke from passing. Smoke could also be blocked if the building has defective internal plumbing. Although this category is not directly related to I/I sources, there may be connections such as area drains, window well drains and roof downspouts at those addresses that were not identified, since smoke would not have been observed exiting these sources. We recommend smoke testing again after the recommended improvements are implemented. Category D consists of sanitary sewer manholes that were smoking at the ground surface around the perimeter of the manhole. Smoke was observed at six such manholes during smoke testing. This most likely indicates that groundwater and /or stormwater can enter the manhole or sewer. Common points of entry are through the joints between precast sections, under the frame or between adjusting rings. 091241.30 - 09/10 3 -1 3. RECOMMENDATIONS AND COSTS With the authorization of the Village of Mount Prospect, Baxter & Woodman has completed this investigation to determine the contributing factors that cause operational problems in the sanitary sewer system and basement backups. The investigation included manhole inspections, sanitary sewer capacity analysis, smoke testing, sewer televising, flow monitoring, and building -to- building canvassing. A significant amount of I/I was identified as part of this study, and additional I/I is likely present but undetectable due to continuous surcharge conditions even during dry weather. Further, considerable sanitary sewer and manhole defects and design issues were identified. Below is a summary of recommended improvements to reduce I/I and increase the full flowing capacity of the sanitary sewers in Basin 37. 3.1 Sanitary Sewer Replacement Several segments of sanitary sewer are recommended for replacement to eliminate multiple maintenance and operational issues (Table 6). Replacement is recommended instead of lining due to the presence of pipe sags and prevalence of shattered pipe. TABLE 6 Recommended Sanitary Sewer Replacement — Phase 1 Manhole Reach Street Pipe Size Pipe Length Estimated From To Location (inches) (lin.ft.) Cost* MH 37S01 MH 37S02 Briarwood Dr. W 8 130 $250 / 1in.ft. MH 37S02 MH 37S05 Briarwood Dr. E 8 590 $250 / lin.ft. MH 37S12 MH 37S16 Lynn Court 10 360 $275 / lin.ft. MH 37S16 MH 38S52 Easement 10 580 $275 / lin.ft. * Installation cost only. Full capital cost is detailed in Section 4 of this report. 091241.30 - 09/10 3 -2 Replacement of the 8 -inch diameter sewers on Briarwood Drive East and West will eliminate multiple physical defects and design issues, including back - pitched or insufficiently sloped pipes, shattered pipes and deteriorated manholes. Replacing pipes with insufficient slope and sags will significantly reduce surcharged conditions, decrease grease and sediment buildup, and increase the full flowing capacity of the pipes during wet weather events. This will make the sewer easier to maintain and help to reduce or eliminate surcharging observed downstream during wet weather events. Eliminating the shattered pipes and deteriorated manholes will significantly reduce I/I on both streets, further reducing surcharging observed downstream during wet weather events. These improvements are also intended to reduce the likelihood of the basement backups that periodically occur on the north end of Briarwood Drive West. Replacement of the 10 -inch diameter sewers on Lynn Court and along the easement terminating at the corner of Phillip Drive and Dennis Drive is intended to alleviate the capacity restriction that causes surcharging of the upstream 8 -inch sewers during wet weather. Sewer televising detected many defects along this sewer segment, including cracked pipes, shattered pipes, protruding laterals and offset joints throughout. These defects were allowing continuous infiltration even during the dry weather conditions present during sewer televising, so they are likely a major source of I/I during wet weather. Replacement of the pipe will eliminate these I/I sources, freeing up more sewer capacity for sewage and wet weather flows generated upstream. The Village should also consider replacing the existing length of 8 -inch diameter trunk sewer on Briarwood Drive East between MH 37S05 and MH 37S09, a length of 900 091241.30-09/10 3 -3 lineal feet (Phase 2). The segments recommended for replacement in Table 6 are higher priority due to the prevalence of both pipe sags and pipe defects allowing I/I to enter. The segment from MH37S05 to MH 37S09 is lined and is likely not contributing much I /I, but it does contain sags and should eventually be replaced to maximize the flowing full capacity of the trunk sewer. The estimated cost for replacement of this segment of 8 -inch diameter sewer is $250 per lineal foot. As part of Phase 2, we also recommend improving the hydraulics of the force main entering the trunk sewer at MH37S06 from the east, if possible. Currently, the 4 -inch diameter force main discharges perpendicular to the flow line of the sewer and creates a significant disturbance to the gravity flow when operating. A possible solution is to redirect the force main downstream of MH 37S06 and connect to the trunk sewer at a steeper angle to help "push" the forced flow down the sewer. This should be done with a new manhole for maintenance purposes. The estimated cost for improvements to the force main and new manhole is $25,000. 3.2 Sanitary Sewer Lining The segment of 8 -inch diameter sanitary sewer on Briarwood Drive East from Manhole 37S09 to 37S12 (approximately 790 lineal feet) is recommended for CIPP lining. Television inspection noted several areas along this segment with cracks and other defects, but they can be corrected with lining as opposed to complete pipe replacement since sags are not as prevalent in this section of the sewer as compared to upstream segments. Estimated lining cost is approximately $40 per lineal foot. 091241.30 - 09/10 3 -4 3.3 Private Property Improvements Correction of defects and removal of inappropriate connections on private property is the responsibility of the property owners. However, the Village should contact property owners to initiate improvements to repair defective laterals and cleanout caps, and to disconnect and re -route illegally connected downspouts and sump pumps. Smoke testing identified a downspout connected to the sanitary sewer at 2953 Briarwood Drive West. This downspout should be disconnected from the sanitary sewer and re- routed to discharge to the ground surface at the homeowners' expense. Illegal sump pump connections were also identified by Village staff at 40 locations in the study area. These sources can contribute inflow in the range of 20 to 30 gpm each on a continuous basis during wet weather, and some of the sump pumps may also contribute flow to the sanitary sewers intermittently during dry weather. Estimated cost to disconnect sump pumps from the sanitary sewer and re -route discharge piping to the stormwater system is $1,200 per property. 3.4 Public Education Program and Ordinance Development The entire length of the trunk sewer in Basin 37 showed heavy grease build -up. This results in a significant reduction in conveyance capacity, and also requires periodic maintenance and cleaning. The restaurants located at the corner of Briarwood Drive North and Algonquin Road have grease traps per Village Code. Since heavy grease buildup was observed upstream of these connections, specifically between Manholes 31 S25 and 31 S26 on the far upstream end of the trunk sewer, it is apparent that the multi - family units north of Algonquin Road are heavy contributors to the problem. 091241.30 - 09/10 3 -5 We recommend the Village conduct a public education program in the multi - family residential neighborhood north of Algonquin Road. This program should focus on the importance of keeping all fat, oil and grease out of the sanitary sewer by disposing of these materials in the trash rather than pouring them down the drain. We also recommend the Village create a Fats, Oil and Grease (FOG) ordinance for all users. The purpose of the ordinance is to control discharges into the public sewerage collection system that interfere with the operations of the system, cause blockage and plugging of pipelines, and interfere with normal operation of pumps and their controls. 091241.30 - 09/10 4 -1 4. SUMMARY The following is a summary of recommendations and costs formulated from the information presented in this report. The recommendations are separated into two phases based on the priority of the work. TABLE 7 Summary of Recommendations and Costs Source Estimated Cost Phase 1 Sanitary Sewer Replacement 8 -inch diameter (720 lin.ft.) $180,000 10 -inch diameter (940 lin.ft.) $258,500 Sanitary Sewer Lining 8 -inch diameter (790 lin.ft.) $ 31,600 Total Construction Cost $470,100 Engineering Design (10 %) $ 47,000 Construction Inspection (10 %) $ 47,000 Contingencies (10 %) $ 47,000 Total Project Cost (Phase 1) $611,100 Phase 2 Sanitary Sewer Replacement 8 -inch diameter (900 lin.ft.) $225,000 Force main Hydraulics Improvements $ 25,000 Total Construction Cost $250,000 Engineering Design (10 %) $ 25,000 Construction Inspection (10 %) $ 25,000 Contingencies (10 %) $ 25,000 TOTAL (Phase 2) $325,000 091241 30 - 09/10 • BROWNSTONE 4 1 1474 I' o at g 01 N N N a o 1 N 1480 ALGONQUIN --► 1482 er CO CO TRAILS CO C., N 11 BASIN 0 °m CO 0 N N DI O VERVIEW 37 M AP 2076 1490 2074 1492 2072 0 / ,_ gCGONQV 2070 . W ' _ E ® MO ° a I N S' / v A Al O 4? b� A� �O n illillillb... ,ye a' ' ° ° V 0 m o c c ��1 1 ? V 4' ° N N N N N N N `mil ti w1 1761 . # 1. ' 0 1763 ',ulo ti 1765 g > r 1767 S 1769 0 703 2?e�7 2115 2820 2803 �� 205 CINNAMON 11 2605 COVE 2880 Cil 411111■•■ 1779 1777 2807 C 2 1781 2809 D 1 1783 2 2811 2 1785 0 OV4 0 2813 1787 2829 1789 • 2815 P 2832 ® 2833 ® P5e4 2834 ` 2836 2835 1791 1793 1792 2 2838 2837 1 ° ' 01 2838 ' 2839 2840 X11 2841 2842 ,�a , 2843 9V4* C RLOTTE R. 2900 4.0.4t# 2902 2901 2904 2903 ?805 ?g AM Sil ,, � 4 2909 1910 300 3001 MANSARD 00 ' 0 M r 0 n 0 n p 300 N CO n O A r 3002 3�0j O 3004 ` - DENN'S DR 41 ■© i IC: °_ HU Lill n A i a X 11 a -- J q , i83 D 185' o = LJ s :k a p illii J K -4 ILI c VICTORIA HILLS 85 H r I ' IR. CHARIOT CT 1751 iii 1719 F. I E I r 1749 EC 1721 1707 Map date: 9 -22 -10 1747 ® 1 72 ' 1723 Printed by JJP /PW 1fC 1709 F:1Projects\SEAN120101BASIN 371OVERVIEW.mxd 2 \� 171 1711 PHAROAH'S 1 1 ■ 31517 t 31519 • 31518 -O • BASIN 37 11 3 I52, 3,522 + � Sanitary Sewer Mains • - ■ 6 RECO i = MMENDATIONS N 4,00 HQG W ■ l R0 31S25 W _©` E ii. -.4, 31S26 S 31E31S28 6 ^ 31530 31831 310532 37S02 37503 C37504 4 37532 37533 37535 37801 • 38S01 37S31 37S30 . 37805 329 • lea Legend 37506 38507 38SLS01 7 if I 4414 375 BASIN 37 OUTLINE SEWER MANHOLES i o Private Owned 37S28 4 0 37S07 it glir 0 Village Owned SEWER MAINS p 4 ' 14 u 3 7so8 363,6 37527 Village Owned 38523 PHASE 1 PHASE 2 37809 37S26 \ 10 0 0 0 37525 O rc 37510 37524 \ C KLOTTE R. \ 37523 \ 37811 \ 37522 37512` 44 i 37821 37820 9 � . 38S50 38S48 • 38549 „Si, I7 a � p o ,__ 38S5 ais 37514 38852 -38553 _ 37S15 37517 38851 36557 37516 / �. 38554 Vii0 37863 i I ❑ 11 375_6 37562 � _r ‘Vir4 i 0 37S611 37819 38858 n € I . v J = D J Nl A a i 38859 J 38T87 m o a 1 I 38567 37S18 = LLL��� --- 38566 wc�roRiA �2 38563 V 38S65 4 C? 1 38564 38568 38569 1 - 43S02 43803 m 38S70 43501 CHAR 43 SO 4 43S05 43506 Map date: 9 -22 -10 o f S0I Printed by JJP /PW 43S07 p F: \Projects \SEAN \2010 \BASIN 371RECOMMENDATIONS.mxd \ 43S08 43S10