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HomeMy WebLinkAboutCOM 0176.123 2006-2008 Bi1151 Page 1 of 1 Murashige, Laura From: Nancy E. Burns [nebpellc@hawaii.rr.com) Sent: Friday, July O6, 2007 8:32 AM To: counciltestimony@co.hawaii.hi.us; Hoffmann, Pete; Pilago, K. Angel; Ford, Brenda; Ikeda, Donald; Naeole, Emily; Yoshimoto, J; Higa, Stacy; Yagong, Dominic; Jacobson, Bob Cc: McClure, Bruce; Galen Kuba; cohmayor@co.hawaii.hi.us Subject: Bill 51 Attachments: July 3 2007 Testimony.pdf Attached please find additional testimony regarding Bill 51. I am hoping that the council and community can work together to resolve drainage and floodplain management issues. There aze many people that aze ready, willing and able to assist you in any way we can. Aloha. Nancy ~ . G' ? ~l Ncnicy 1. Bttrn.r, P. E., LLC ~ ` - ;3-1-18% Krro ~Slreet Kuilr~a Kona, HaH~uii 947-10 Tel. (Y081 32.5-318? ~ F~tx (808) 3Z~-104J nebpellc(~haiti~ari. rr. corn « » Comm. No. ~7~ Ref. Tos_Ijrueees~ I Ref. Date 0 ZUU7 ,r 7/6/2007 July 3, 2007 Honorable Pete Hoffmann, Chairperson Hawaii County Council 333 Kilauea Avenue Second Floor Hilo, Hawaii 96720 Testimony on Bi11 51, Draft 5 Proposed Amendments to Chapter 27 of the HCC Honorable Chairperson Hoffmann and Members of the Hawaii County Council, I attended the ad hoc committee meetings that were held on June 22 and June 26 as a member of the public I came away from those meetings with the feeling that there was still a great deal of confusion about urban drainage design and flood plain management and the regulations that govern each of these items. I am especially concerned that some believe there is a huge inadequacy in the design storms currently being used to size drainage systems. Some of the confusion seems to stern from a lack of understanding of the difference between urban drainage system design and flood plain management. According to the Standard Handbook for Civil Engineers. Third Edition, Frederick S. Merritt, Editor, McCmaw-Hi1lBook Company, 1983, "Flood problems and surface drainage, as concerns of community and regional planning studies, differ in degree and severity. The principal concern with flooding is the desire to avoid injury and loss of life and reduce property damage caused by major floods (those having a recurrence interval of 25 to 100 years). Surface-drainage systems, on the other hand, aze primarily concerned with convenience and providing access to property during relatively minor storms (those having recurrence interval of 2 to 10 years.)" The County of Hawaii currently mandates a 10 year storm be used to size surface drainage facilities which is at the high end of the desi~ storms used by most communities. Hawaii County uses the 100 year storm to size systems designed to protect against major floods. This also is also a conservative storm. It seems that some members of the County Council may be confusing urban drainage design and flood plain management design. 1 urge you to consult with the Department of Public Works and other professional civil engineers before assuming that the current codes and standards are inadequate. Based on my 17 years of designing drainage systems in the County of Hawaii I would say that the current requirements of Chapter 27 and the County of Hawaii Storm Drainage Standards are significantly above average and more than adequate. I have prepared drainage plans and studies in many different parts of the Country and my professional opinion is that Hawaii County has some of the most conservative codes I have come across. For example, Chapter 27 does not allow a rise in the base flood elevation. FEMA allow a rise of up to one foot. Many communities that I have worked in also allow the one foot rise. Hawaii County is also the only county I have ever worked in that requires all increase in the 10 year storm runoff to be disposed of onsite. Most communities only require detention and many communities also use storms of lesser magnitude such as the 2 year or 5 yeaz storms. I have been told that some communities in California require the 25 year storm for certain drainage conditions. This is also the case here in Hawaii where under certain conditions, the 25 or 50 year storm is used to size culverts crossings of some roads. I ask once again that the County Council further invesfigate whether the County's current design storms are inadequate before arbitrarily imposing standards that will negatively impact the cost of living and also require addiflonal tax dollars for maintenance. Design standards should not be changed unless it can be shown that the cost to design, construct and maintain the required drainage systems provides a net benefit to the tax payers of this county. I am in agreement with members of the ad hoc committee who believe some of the proposed amendments could create a negative impact regarding public health and safety as large ponds may need to be constructed which could put residents at risk should there be a large earthquake or extreme flood situation that causes dams to fail. Before passing the proposed amendments,l ask that you consult with professional engineers with experience on the Big Island as this island is truly unique in its geology, topography, climate and environment. Mainland methods and standards often aze not compatible with our environment. If the Council is truly concerned with protecting public health and safety I recommend that they appropriate adequate money for flood studies. These studies should result in the mapping of drainage channels and perhaps the creation easements for those channels which prohibit habitable structures within the easements. Topographic mapping at 2 foot contour intervals should be obtained so that watershed divides can be accurately drawn. Better soil mapping is required so that runoff can be more accurately esfimated. More rain gauges should be established and data collected and analyzed so that there is more science and less speculation as to how much rainfall is really causing flood problems. Records of flood damage and the causes of the damage should be kept and analyzed. Only then will we be able to determine whether the design storms currently being used are adequate. Flood studies should also include recommendations for regional flood plain management improvements necessary to protect vulnerable communities. Cost estimates and implementation plans should also be provided for any recommended improvements. I recommend approval of the amendments proposed by the Department of Public Works at the earliest possible date so that the County remains in compliance with FEMA requirements. I sincerely appreciate the opportunity to provide testimony on the subject of Chapter 27. I can be reached at 325-3182 or 960-5896 should you have any questions regazding my testimony. Respectfully Submitted, /~c,J~'7"'~ ~J-t.~~' Nancy E. Burn/ s, P.E. ec Bruce McClure, Director, Depamnent of Public Works Galen Kuba, Division Head, Department of Public Works, Engineering Division Mayor Hany Kim