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Floodproofing TECHNIQUES

City of Englewood

As a part of the Flood Study, Calibre completed a review and analysis of various floodproofing techniques, including conversations with and reviewing the advisement materials of FEMA, USACE, the City and County of Denver, the City of Aurora, and Urban Drainage and Flood Control District. The floodproofing techniques included herein are specifically relevant to this area of Englewood.

We have provided several resources that can help the City and Englewood homeowners assess flood risk on their particular property, and help citizens to determine appropriate floodproofing measures.  

 

It should be noted that there is no well-defined standard for determining needed floodproofing.  All homeowners must decide how much risk they are willing to take and must work with the City and/or a Professional Engineer (PE) to plan for floodproofing that the homeowners feel covers their level of risk.  

 

Resources provided herein include the narratives, a series of maps, a simplified flow chart to help determine the need for floodproofing, and an initial cost estimate spreadsheet to determine how much floodproofing might cost in a variety of scenarios.

INTERACTIVE MAP: REPORTED FLOODING & RELATED PROBLEMS

Reported Flooding & Related Problems.PNG

This interactive map shows key locations of flooding as determined by modeling, citizen input, and City records. It also includes images, comments about flooding, basin boundaries, and other relevant information. This map can be used to see where incidents of flooding have been reported in relationship to the Areas of Probable Flooding in the 100-year Event.

notes about floodproofing

The most immediate and cost-effective way to reduce flood risk is to buy flood insurance.  If you believe you may be subject to flooding in the future, we recommend that you consider getting flood insurance. Floodproofing is another way you can protect yourself.  It is likely that a comprehensive program of storm drainage improvements will take years to be implemented by the City.  In the mean time, you can help reduce flood hazard by implementing floodproofing on your property. Here are some notes about floodproofing techniques recommended in this study:

  • Floodproofing techniques are suggested based on type and depth of expected floodwaters

  • When properly designed and installed, these techniques can greatly reduce or mitigate flood damage

  • Flood improvements must be approved by the City of Englewood Public Works Staff and proper permitting must be obtained from the building department

  • Immediate neighbors must be notified of the improvement

  • Some flood-proofing techniques may have impact on adjacent neighbors, and, therefore, must be designed by an engineer and approved by the City such that flooding of adjacent properties is not worsened

The following narrative provides a reasonable method for determining the need for floodproofing on your home.  This narrative is not comprehensive in that it does not cover all circumstances.  It is important  for the homeowner to consult an engineer and the City as part of the floodproofing process to help customize a set of improvements for your property.

1.  Consult Flood Maps - This link leads to a set of eight maps.  These maps show approximate level of flooding for four storm levels, 10-year storm, 25-year storm, 100-year storm, and two times the 100-year storm.  Four of the maps reflect flooding with storm sewer operating normally, and four reflect conditions with plugged storm sewers.  By consulting these maps, you can get a sense of the severity of flooding at your location as flooding becomes more extreme for differing storm events.  Rather than looking at the storm frequency (10-yr, 25-yr, etc.), one might consider the following as a guide:

 

  • 10-year storm, very likely to occur in the next few years, possible in any given year.

  • 25-year storm, somewhat likely to occur in the next decade, possible in any given year.

  • 100-year storm, somewhat less likely to occur in the next decade, within the realm of possibility in any given year.

  • Twice the 100-year storm, very unlikely to occur but within the realm of possibility.


2.  Get Flood Insurance - Based on your location, the likelihood of flooding, and the flood risk you are willing to take, determine whether to obtain flood insurance.  It is highly recommended to consider flood insurance, even if you are outside of the expected flood areas, especially if you or your neighbors have experienced flooding and if you are not clearly on higher ground.


3. Consult the Floodproofing Flowchart - This flowchart gives you guidance as to what sorts of techniques should be provided of given conditions.  Note that if you are expecting flooding in excess of 3' above the grade adjacent to your home, structural damage is a possibility, and even full structural collapse.  Normal floodproofing is not adequate above 3' and is questionable over two feet, given the strength and power of water to collapse walls at certain levels of pressure.  


4. Consult the City of Englewood Public Works and Building Departments and consider hiring a civil engineer to assist in evaluating your home and preparing a final plan for floodproofing.  Some funding may be provided to assist homeowners in floodproofing, so check with the City regarding status of funding assistance programs.


5.  Develop an emergency plan with your family.  Every home that is subject to flooding should have an emergency plan for evacuation in case of a severe storm.  Some of the conditions that have a high life safety risk include the following:

  •  Homes subject to flood waters and having a basement. Under certain circumstances, individuals can be trapped in these homes.  This is especially dangerous without secondary access to an unflooded location.  It is highly recommended that sleeping quarters are not included in the basements of homes of this type.

  • Homes with external stairwells to a basement.  Doors in stairwells become inoperable during inundation and do not provide an exit path.  A secondary path to a location above the water level is necessary.  It is highly recommended that sleeping quarters are not included in the basements of homes that are subject to an excess of 2 to 3' of flooding against the structure.

 

 

 

 

 

 

 

 

 


 

Floodproofing Guidance

Understanding a

"STorm Event"

What does it mean to experience an

"X-Year Storm Event"?

An Analogy:

Think of a 5-year storm event as a cup with four white marbles and one red marble. If you randomly pick one marble out of five, the odds of you picking out the red marble is one out of five. If you replace the red marble and pick again, the odds of picking the red marble are still one out of five. But, you could in fact pick the red marble twice in a row. This is the same with the 5-year storm event. The odds of experiencing the 5-year storm are one out of five in a given year, but it could happen twice in a row, even in the same week.

The same is true for a 25-year, 50-year, or 100-year storm event. A 100-year storm event is like having 99 white marbles and one red marble. The odds of picking a red marble are one out of 100, but you could draw that red marble at any time, even twice in a row.

Find out which floodproofing techniques

may work for you!

This flowchart was developed as a quick at-a-glance tool to determine whether homeowners should implement floodproofing on their properties. The flowchart is meant to be a guidance document, and homeowners are encouraged to use their discretion and past experience to determine risk of flooding.

Image: Sample window well provided by Window Well Experts. 

Image: Sample egress window provided by WMGB Home Improvement.

Flood Insurance is available to anyone, regardless of whether your property is within a delineated floodplain or not. The FEMA NFIP website includes links to maps showing expected flood areas. All homes in or near delineated flood areas should consider the benefits of flood insurance. In addition to homes within these delineations, other homes are or may be subject to localized flooding. Therefore, even if your home is outside the delineated flood limits, it may be advisable to consider insurance.

 

Up to $250,000 of structural coverage is available through the National Flood Insurance Program (NFIP). The 2018 rates can be downloaded using the link above.

 

Please see the FEMA NFIP website for more information.

 

The subject study was limited to the North Englewood Basin, Central Englewood Basin, South Central Englewood Basin, South Englewood Basin, and Northeast Englewood Basin as delineated in the 1998/1999 OSP. For a map of those specific basin delineations, please see the HOME PAGE. Citizens outside the limits of the subject areas should also consider Flood Insurance.

To learn more about the National Flood Insurance Program, including a manual and rates, please use the buttons below.

Flood insurance

Floodproofing Techniques

Floodproofing can be very effective in reducing or eliminating damage caused by floodwaters.  There are multiple ways of floodproofing a home, depending on certain criteria, such as if a house has a basement or crawlspace, how deep the expected floodwaters are, and other defined criteria.

 

Please see the figures below for more details on floodproofing techniques, including how and where they should be applied. 

Any floodproofing technique should be reviewed by the City of Englewood and a Professional Engineer (PE).

Click on one of the techniques below to view the cut sheet or utilize the slideshow below.

NOTE: Any floodproofing technique must be reviewed by the City and a Professional Engineer (PE) before you implement it on your property. This is critical for proper installation, proper design, and evaluating impacts on the overall system.

Egress Windows

Closure Panels, Well Raising, & Flood Shields

Allowing Flooding w/o Structural Damage

SUMP Pump

Inflatable & Removable Flood Control

Component Relocation/Elevation

Flood Damage Resistant Materials

Raising/Jacking the Home

References

1.US Army Corps of Engineers. Flood Proofing Techniques, Programs, and References. Omaha: US Army Corps of Engineers, 2000. (pp. 1–32).

2. FEMA. FEMA P-259: Engineering Principles and Practices for Retrofitting Flood-Prone Residential Structures. FEMA, 2012.

3. FEMA. FEMA P-259: Engineering Principles and Practices for Retrofitting Flood-Prone Residential Structures. FEMA, 2012.

4. FEMA. FEMA P-312: Homeowner’s Guide to Retrofitting: Six Ways to Protect Your Home from Flooding. FEMA, 2014.

5. MegaSecur-WaterGate. “MegaSecur | Products.” Retrieved 2018 10 25 from:
www.megasecur.com/en/products/

6. US Army Corps of Engineers. Flood Proofing Regulations. Washington DC: Army Corps of Engineers, 1995. (pp. 1–85).

7. WMGB Home Improvement. “Advantages of Basement Egress Windows.” Retrieved 2018 10 15 from:
www.wmgb.com/egress-windows/advantages-basement-egress-windows/

8. Sneath, Sara. NOLA.com | The Times-Picayune. “Levee-ing the Odds: Southwest Louisianians Build Their Own Flood Protection.” Published 2017 08 06. Retrieved 2018 10 25 from:
https://www.nola.com/environment/index.ssf/2017/08/levee-ing_the_odds_southwest_l.html

9. FEMA. FEMA 102: Flood Proofing Non-Residential Structures. Chapter 5: Costs and Benefits of Floodproofing Methods. FEMA, 1986.

10. Window Well Experts. “Atrium Window Well Covers.” Retrieved 2018 10 25 from:
https://windowwellexperts.com/window-well-covers/atrium-window-well-covers/

11. Flood Panel. “Flood Protection Products.” Retrieved 2018 10 25 from:
https://www.floodpanel.com/flood-protection-products/

12. FEMA. FEMA 551: Selecting the Appropriate Mitigation Measures for Floodprone Structures. FEMA, 2007.

13. National Trust for Historic Preservation. “Wet Floodproofing.” Retrieved 2018 10 25 from:
http://floodquiz.savingplaces.org/wet-floodproofing/#.W9DRq0tKiUk

14. FloodVent.com. “How Do Flood Vents Work?” Retrieved 2018 10 25 from:
http://www.floodvent.com/how-vents-work.html

15. JEA. “Backflow.” Retrieved 2018 10 25 from:
https://www.jea.com/about/water_supply/backflow/

16. GlobalIndustrial.com. “Quick Dam 10’ Flood Barrier – 1 Barrier/Pack QD610-1.” Retrieved 2018 10 25 from:
https://www.globalindustrial.com/p/janitorial-maintenance/leak-diverter/leak-diverter-barriers-sandbag/quick-dam-10-flood-barrier-1-pack?infoParam.campaignId=T9F&gclid=Cj0KCQjwsMDeBRDMARIsAKrOP7E5TJwhk7AHYacDz9SrUbZ8nJC4oNAE4ML2F9F55aSQnvj_0ifMdtEaAhkkEALw_wcB

17. GlobalIndustrial.com. “HydraBarrier Ultra Sandbag Alternative, 24’ L x 6” H – HBU-24. Retrieved 2018 10 25 from:
https://www.globalindustrial.com/p/janitorial-maintenance/leak-diverter/leak-diverter-barriers-sandbag/hydrabarrier-ultra-24-ft-long-6-in-high?infoParam.campaignId=T9F&gclid=Cj0KCQjwsMDeBRDMARIsAKrOP7GJb_FZ9m2PdtDArMbJtOqFrzeEJIwUk_Hh6Uout0YoVNZT5ClQ3UQaArdNEALw_wcB

18. Home Safety Solutions. “Egress Windows.” Retrieved 2018 10 25 from:
https://www.homesafetysolutionsinc.com/egress-windows/

19. Basement Windows of Denver. “Basement Egress Windows Contractor.” Retrieved 2018 10 25 from:
https://www.basementwindowsofdenver.com/egress/basement-egress-contractor/

20. FEMA. FEMA 551: Selecting the Appropriate Mitigation Measures for Floodprone Structures. FEMA, 2007.

21. US Army Corps of Engineers Omaha District. Nonstructural Flood Damage Reduction Assessment for Kaycee, Wyoming. Omaha: US Army Corps of Engineers, 2004.

22. Sheaffer, John R. Introduction to Flood Proofing An Outline of Principles and Methods. Illinois: University of Illinois, 1967.

23. US Army Corps of Engineers Levee Safety Program. US Army Corps of Engineers Levee Portfolio Report: A Summary of Risks and Benefits Associated with the USACE Levee Portfolio. US Army Corps of Engineers, 2018.

24. FEMA. FEMA-348: Protecting Building Utility Systems From Flood Damage: Principles And Practices For The Design And Construction Of Flood Resistant Building Utility Systems. U.S. Department of Homeland Security, FEMA, 2017.

25. FEMA. FEMA P-936, Floodproofing Non-Residential Buildings. FEMA, July 2013.

26. Powertools, et al. “Ardex 8+9 Waterproofing Compound.” Tools4Flooring.Com. Published 2018 03 29:
www.tools4flooring.com/ardex-8-9-waterproofing-compound.html?gclid=CjwKCAjwyOreBRAYEiwAR2mSkttaZ4bZ6Pr6bpUnS5_BInTBY2rhuFZt8VslEQIxcZGssSaWq2CSeRoClJUQAvD_BwE

27. C, Dave, et al. “Marine Teak Lumber .875’ Thick.” Boat Outfitters. Published 2018 08 09:
www.boatoutfitters.com/marine-teak-lumber-7-8-inch-thick?gclid=CjwKCAjwyOreBRAYEiwAR2mSkrgu1nP2JC9fDkspjgBZcy1uujHrdN_0NNrrPualCkBBbFhLokRWFhoCAn4QAvD_BwE.

28. Global Industrial. “DRYLOK EXTREME Masonry Waterproofer, White 5 Gallon Pail - 28615.” Global Industrial. Retrieved 2018 11 07:
www.globalindustrial.com/p/janitorial-maintenance/paint/liquid-coatings/extreme-masonry-waterproofer-white-5-gallon?infoParam.campaignId=T9F&gclid=CjwKCAjwyOreBRAYEiwAR2mSkpbPk-Bs3DaA6QW4GbXQN6evqQrgumx1M6m7v9tu1lQ3x5wIiYcOyxoCbisQAvD_BwE.

29. UDFCD. Urban Drainage and Flood Control District Storm Drainage Criteria Manual Vol 1. Urban Drainage and Flood Control District Storm Drainage Criteria Manual Vol 1, USDCM Volume 1, 2016.

30. FEMA. “Homeowner's Guide to Retrofitting.” Elevating Your Home, www.fema.gov/pdf/rebuild/mat/sec5.pdf.

31. Improvenet. “How Much Will It Cost to Raise a House Foundation.” (2018 10) Retrieved from: https://www.improvenet.com/r/costs-and-prices/raise-foundation-cost-estimator

 

32. Anderson, Murray. How Stuff Works. “How Sump Pumps Work.” (2020 03 05) Retrieved from: https://home.howstuffworks.com/home-improvement/plumbing/sump-pump1.htm

 

33. Service One. “Sump Pump FAQs.” (2018/11/07). Retrieved from: https://www.serviceone.com/blog/article/sump-pump-faqs

Published June 11, 2019

Revised December 2, 2019

Revised February 6, 2020

Revised March 7, 2020

Revised March 17, 2020

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