Extreme Wet Weather in Brookfield. How to Keep Your Basement Dry During Heavy Rains and Floods

Transcription

1 Extreme Wet Weather in Brookfield How to Keep Your Basement Dry During Heavy Rains and Floods

2 History of Flooding in Brookfield Brookfield is at the top of the subcontinental divide, we don t have flooding, or so we were told Untrue! Like other municipalities, Brookfield is subject to flooding Well documented history of flooding in the City, particularly in low lying areas, wetlands, floodplains, and ditched areas such as Dousman Ditch and Butler Ditch

3 History of Flooding in Brookfield Historic flooding events: March 1897 June 1917 June 1940 March 1960 July 1964 September 1972 April 1973

4 History of Flooding in Brookfield Most recent events August 6, 1986 June 20 and 21,1997 August 6, 1998 June 7 and 8, 2008

5 Recent Precipitation Records Annual Precipitation P re c ip ita ti o n (in c h e s ) Year Average Precipitation Annual Precipitation

6 Effects of Severe Wet Weather Widespread flooding Ditches and storm sewers overloaded Ponding water in streets and yards Closed streets Damage to roads Eroded streambanks Water in basements Basement backups

7 Hydrologic Cycle

8 Hydro-illogic Cycle Solutions too costly Do nothing Rains come Panic ensues Dry weather returns Study problem Identify solutions

9 Breaking the Cycle August 6, inches of rain in 24 hours 100 year storm; good for another 100 years? June 20-21, inches of rain in 26 hours A fluke? August 6, inches of rain in 8 hours Something has to be done!

10 City Established Citywide Flood Task Force in 1999 Reviewed causes of flooding Developed understanding of stormwater drainage Established design standards for infrastructure dealing with drainage and wastewater Explored relationship between stormwater drainage and sewer backups into basements Developed recommendations to address flooding, floodplain management, stormwater drainage, and wastewater conveyance

11 City Established Citywide Flood Task Force in 1999 Reviewed causes of flooding Developed understanding of stormwater drainage Established design standards for infrastructure dealing with drainage and wastewater Explored relationship between stormwater drainage and sewer backups into basements Developed recommendations to address flooding, floodplain management, stormwater drainage, and wastewater conveyance

12 Causes of Flooding Too much rain; more than storm sewer system or ditches can handle Properties constructed in floodplains Floodplains have been filled in the past Prior to 1999, some development occurred without management of stormwater runoff during extreme events Needed to implement previously identified stormwater improvements in Brookfield

13 City Established Citywide Flood Task Force in 1999 Reviewed causes of flooding Developed understanding of stormwater drainage Established design standards for infrastructure dealing with drainage and wastewater Explored relationship between stormwater drainage and sewer backups into basements Developed recommendations to address flooding, floodplain management, stormwater drainage, and wastewater conveyance

14 Stormwater Drainage Different than flooding Flooding is when rivers and streams overflow their channels and water occupies floodplains Stormwater drainage is conveying stormwater runoff before it gets into a stream or river Stormwater management requires establishment of a standard for design for which runoff from such a storm is adequately handled

15 City Established Citywide Flood Task Force in 1999 Reviewed causes of flooding Developed understanding of stormwater drainage Established design standards for infrastructure dealing with drainage and wastewater Explored relationship between stormwater drainage and sewer backups into basements Developed recommendations to address flooding, floodplain management, stormwater drainage, and wastewater conveyance

16 Design Standards for Drainage Two standards established Minor stormwater conveyance systems (storm sewers, swales and ditches) should convey runoff from a 10 year storm Major stormwater conveyance systems (streets, detention ponds) should handle runoff from a 100 year storm without flooding structures Yes, streets are designed to convey runoff from the 100 year storm; this is not a failure they are meant to have water on the street

17 Design Standards for Drainage Why does the proverbial 100 year storm occur more frequently than once every 100 years? The storm described as the 100 year storm has a one percent chance of occurring in any given year The 100 year storm is based on a statistical analysis of historic rainfall and is affected by cyclical climate patterns

18 What Does the 100 Year Storm Look Like? Varies depending on duration 1.41 inches of rain in 15 minutes 2.82 inches of rain in one hour 4.70 inches of rain in six hours 5.25 inches of rain in 12 hours 5.88 inches of rain in 24 hours This is shown graphically on next slide

19 What Does the 100 Year Storm Look Like? Year Storm for Brookfield Area Depth (inches) Time (hours)

20 City Established Citywide Flood Task Force in 1999 Reviewed causes of flooding Developed understanding of stormwater drainage Established design standards for infrastructure dealing with drainage and wastewater Explored relationship between stormwater drainage and sewer backups into basements Developed recommendations to address flooding, floodplain management, stormwater drainage, and wastewater conveyance

21 Relating Stormwater Drainage to Sewer Backups Brookfield has two separate sewer systems Storm sewer system to convey rainfall runoff Sanitary sewer system to convey wastewater from houses, businesses and industry During rain events, some rainfall runoff can enter into the sanitary sewer system This overloads the sanitary sewer causing basement backups Overloaded private laterals can backup into homes Overloaded public sewers can backup into homes

22 Relating Stormwater Drainage to Sewer Backups If the two sewer systems are separate, how does stormwater get into the sanitary sewer? Inflow Rainfall runoff gets into the sanitary sewer directly Infiltration Rainfall runoff gets into the sanitary sewer as it infiltrates into the ground Together these are called I/I

23 What are sources of I/I? I/I on the public side of the sewer system Leaking sanitary sewer mains Leaking sanitary sewer manholes Cross connections with storm sewer (inlets inadvertently connected to the sanitary sewer) Someone opens a sanitary sewer manhole cover to drain a flooded street

24 What are sources of I/I? I/I on the private side of the sewer system Leaking laterals to private property Leaking sewer cleanouts in yards Illegal connections to the sanitary sewer Downspouts Sump pumps Yard drains Failed sump pumps, leaking basement walls, or rain water entering the floor drain

25 City Established Citywide Flood Task Force in 1999 Reviewed causes of flooding Developed understanding of stormwater drainage Established design standards for infrastructure dealing with drainage and wastewater Explored relationship between stormwater drainage and sewer backups into basements Developed recommendations to address flooding, floodplain management, stormwater drainage, and wastewater conveyance

26 Recommendations Develop a City wide stormwater management plan Develop a Stormwater Ordinance Obtain easements for and maintain drainageways, swales, etc. Evaluate filling and grading of properties for drainage concerns More actively manage the floodplains Remove some structures from floodplains

27 Recommendations Provide citizen education about drainage, sanitary sewers, and floodplain issues Maintain sanitary sewer system to remove sources of inflow and infiltration (I/I) Construct improvements to the storm water drainage system as identified in the city wide stormwater management plan Construct improvements to the sanitary sewer system to increase conveyance

28 So What s Been Done? Each of the recommendations from the City Wide Flood Task Force Report have already been or are being implemented Stormwater management plan for the whole city was completed 6 years ago Stormwater ordinance passed in 2000 City continues to obtain stormwater easements when it can and maintain them City reviews grading of properties

29 So What s Been Done? Adopted updated floodplain maps from FEMA Purchased and removed numerous houses from the floodplain. In some cases excavated the land to provide area for flood waters to go Continue to educate the public about flooding and basement backups Fixing leaks in sanitary sewers and manholes Implementing improvements identified in the stormwater management plans Increased capacity of sanitary sewers

30 Is the Problem Finally Solved New infrastructure, policies and programs have improved the ability for the City to handle severe wet weather Continue to design to the new standards However, there is no guarantee that a larger storm is not on the horizon, so no guarantee that there will not be flooding or basement backups Improvements reduce frequency and severity of flooding and basement backups

31 When will the City be Done? Never Constant maintenance is required to repair existing and aging infrastructure Continuously monitor new development and redevelopment for stormwater issues Education is continuous as each property impacts the sewer system & other properties City will continue to implement new technologies for constant improvements

32 June 7-8, 2008 Storm So with all the City had done to date, why was there still flooding on June 7-8, 2008? This storm dumped 5.8 inches of rain in about 8 hours, exceeding the 100 year storm (1 percent storm) which has 5.8 inches of rain in 24 hours Widespread power outages impacted sump pumps at over 1,000 houses No municipal system is designed to handle that amount of rain The Governor declared a State of Emergency making us eligible for FEMA disaster relief funds

33 June 7-8, 2008 Storm June 2008 Rain Storm Depth (inches) :00 21:00 2:00 7:00 12:00 17:00 22:00 Rainfall - Brookfield west side 100 Time year (Saturday storm curve 6/07 - Sunday Rainfall 6/08) - Brookfield east side

34 Wisconsin: 14-Day Precipitation Valid at 6/16/ UTC Radar image of precipitation in June 2008

35 June 7-8, 2008 Flood Widespread power outages to over 1,000 houses resulted in failed sump pumps, so the crocks overflowed to the floor drains This increased flow from the floor drains quickly overloaded the sanitary sewers Downstream of the power outage area, flow in an interceptor sewer skyrocketed from 2 million gallons per day (MGD) to over 28 MGD in less than 2 hours

36 June 7-8, 2008 Flood High flows went to Brookfield s wastewater treatment plant where plant flow increased from an average day flow of 7 MGD to about 68 MGD Plant capacity tops out at 50 MGD Accordingly the City did not meet its permit limits for treating the wastewater during the storm

37 June 7-8, 2008 Flood Impacts on properties included: 267 properties experienced basement backups Basement backups concentrated along major sewer interceptors in low lying areas and downstream of areas with power outages Another 1,019 properties had water damage to their basements from failed sump pumps, leaking walls, window wells, etc.

38 June 7-8, 2008 Flood Impacts on properties included: Power outages resulted in failed sump pumps and water entering sanitary sewer system through basement floor drains. These then backed up into other houses further downstream Homes located in floodplains flooded, but this is not a failure of the system since

39 Floodplains are Expected to Flood

40 Failed Sanitary Sewer Lift Station The Greenfield Avenue sanitary sewer lift station failed during the rain storm Resulted in basement backups in the area Pumps were put back into service as soon as the City became aware of the failure Improvements scheduled to provide remote control of the station from the wastewater treatment plant in 2009

41 Pictures from the June 2008 Flood Note the floating firewood

42 Ditches overloaded, excess runoff uses street as conveyance

43 Floodwaters overflowing the street into front yards

44 Excess runoff floods streets and yards

45 This looks like fun, but it can be quite dangerous and is highly discouraged

46 There s always someone who thinks they can make it through the floodwaters they are deeper than they look for safety sake, stay out

47 There IS a street in here somewhere this is not lakefront property notice the height of the mailbox

48 Better or Worse? The June flood impacted the City significantly but not as severely as previous floods Improvements in infrastructure, policy and programs reduced the impact of the storm Areas that had previously been devastated in previous storms were impacted much less by this storm

49 Success Stories Burlawn area greatly improved Lamplighter Park pond was enlarged and new storm sewer and sanitary interceptors were constructed and leaks repaired Flood was generally confined to detention pond and low lying streets A handful of basement backups this time vs. hundreds in 1997 and 1998 Limited damage caused by failed sump pumps

50 Flooded Lamplighter Park Pond: View from Director of Public Work s home Notice mulch line indicating the height of the flooding 5:15 a.m. 6/8/08

51 A closer look at the flooded pond and flooded street 5:20 a.m. 6/8/08

52 Flooded Lamplighter Park Pond Note the basketball hoop Trees in the middle are actually on an island that is now flooded Playground is completely submerged 5:30 a.m. 6/8/08

53 Success Stories Rosedale area greatly improved Previous years this area had hundreds of basement backups, only a handful in 2008 Major interceptor constructed to increase capacity from the area Storm sewers installed to improve drainage Limited damage primarily caused by failed sump pumps

54 Success Stories Post Road area greatly improved No basement backups reported Diversion sewers constructed to use capacity in other sewers Repaired leaks in pipes and manholes Handful of homes with damage primarily from failed sump pumps or leaking walls

55 Success Stories Imperial / Wessex area suffered basement damage, but mostly from overflowing sump crocks, not from basement backups which had plagued this area in the past Sanitary sewer interceptor constructed and leaks in manholes and sewers repaired Most damage related to power outage and failed sump pumps

56 Success Stories Weston Hills area reported no damage Houses on Baythorne Way had flooded in previous storms Storm sewer installation under Brookfield Road seems to have alleviated that issue

57 Success Stories The northeast industrial area used to flood during every heavy rain Minimal flooding in the area City has installed detention pond in the area and major storm sewer City worked with Wauwatosa and Union Pacific Railroad to install larger storm sewer under the 27 sets of tracks in the Butler yard located east of N. 124 th St.

58 More yet to do Despite our successes, there were still areas impacted by the floods City will continue to implement infrastructure improvements Maintenance of existing infrastructure is on-going Adherence to policies and programs will continue also Property owners can also help themselves

59 What Can a Property Owner Do? Improve drainage around your property and away from your house remember, water runs downhill Ensure you have a way of conveying water from your basement if it gets there Keep drainage ways clear Install basement backup protection devices

60 What Can a Property Owner Do? Improve drainage around your property and away from your house remember, water runs downhill Ensure you have a way of conveying water from your basement if it gets there Keep drainage ways clear Install basement backup protection devices

61 Keep Water Away From the House Grade yard away from the house or install a swale to convey water away from house Raise window wells consider covers Install clay fill around foundation soil settles with time and needs to be replaced Mudjack or replace all settled patios, driveways and sidewalks Repair foundation drain tile, basement walls and basement floor if cracked

62 Keep Water Away From the House Clean gutters and downspouts regularly Extend downspouts away from the house Discharge downspouts overland and not to a ditch or storm sewer Discharge sump pump hose away from the house and your neighbor s house Allow WE Energies to cut / trim trees near power lines to minimize power outages

63 What Can a Property Owner Do? Improve drainage around your property and away from your house Ensure you have a way of conveying water from your basement if it gets there Keep drainage ways clear Install basement backup protection devices

64 Get Water Out of the Basement Ensure sump pump(s) is large enough to handle flow coming into the crock Properly size fuses or circuit breakers to handle the size of your sump pump(s) Check sump pump operation regularly Consider installing a battery backup for your sump pump during power outages Consider having a spare sump pump on hand in case the existing one fails

65 Get Water Out of the Basement Do not allow stormwater drainage to go down floor drain it overloads the sewer Do not bail sump crock into floor drain or laundry tub it overloads the sewer Instead pump excess water out a window well or other opening to grade with your extra sump pump, or haul water upstairs and dump outside

66 What Can a Property Owner Do? Improve drainage around your property and away from your house Ensure you have a way of conveying water from your basement if it gets there Keep drainage ways clear Install basement backup protection devices

67 Keep Drainage Ways Clear If there is a ditch enclosure in your yard, consider requesting the City to remove it A ditch enclosure is a former ditch with a pipe in it and covered over with soil Remove existing and do not install structures, fences, or landscaping in drainage easements or drainage ways Keep floatable materials (firewood, mulch) out of drainage ways they plug drains Clear debris from plugged inlets if they plug

68 What Can a Property Owner Do? Improve drainage around your property and away from your house Ensure you have a way of conveying water from your basement if it gets there Keep drainage ways clear Install basement backup protection devices

69 Basement Backup Protection Add a water sensing alarm in your basement which sounds an alarm when it detects water on the floor Consider installing a backwater valve in your sewer lateral Consider installing hung plumbing with a sealed crock to pump wastewater from basement fixtures and floor drain Repair leaks/remove roots in sewer lateral

70 How to Keep your Basement Dry

71 Summary Extreme wet weather events are likely to occur again The City will continue to improve infrastructure and implement policies and programs to minimize the impact and severity of flooding and basement backups Property owners can and should also take steps to protect their property from flooding and basement backups

72 Questions? For questions about how to improve drainage around your house or to determine if you have an illegal sewer connection: Contact City Engineering at (262) For questions about floodplains: Contact Planning at (262) For requests for re-ditching: Contact Highway Division at (262) To report a basement backup: Contact the Treatment Plant at (262)