Loading...
HomeMy WebLinkAboutCOM 0560.020 2002-2004 Ilnflversity Te~rac~ Scott L Andrews 369 Nene Street Hilo, Hawaii r„ „ 2/6/04`,, c r- ~ _ l: I'm a member of the Hilo Bay Watershed Advisory Group. It is a part of the Statewide Watershed Project that is collectuig public input on the seven worst problem watersheds in the State of Hawaii. Peter Rappa, the head investigator on this project says s that Hilo Bay fails the water standards by the EPA and the state Department of Health_ My concern is the pollution of Hilo Bay. We have had recent flooding in this area that contributed to the damage of down town HIlo and the soccer fields. Much pollution flowed into HIlo Bay from garbage, sediment, flooded out cesspools, and many other sources. I would like to quote a few excerpts from: (c) 2002 Environment Hawai i, Inc. Volume 12 Number 7 (January 2002) Hardened Banks, Channelized Streams Climb Ever Upwards after Hilo Flood Soon after the flooding, the county Department of Public Works asked the state Commission on Water Resource Management whether any of the planned projects might require a stream channel alteration permit from the conmussion. (The county was fined by the commission in the mid-1990s for failing to obtain a permit for construction of the Alenaio flood control project.) There's another odd characteristic about this youthful land: many of the stream channels, still in their formative years, are interrupted. Try hiking up the Alenaio Stream between Komohana Street and Kaumana Drive. A few hundred yards past Komohana the stream channel vanishes. By the time you pick up Alenaio just downstream of its crossing under Kaumana at Chong Street, the channel is again deep and well-defined -and goes under a different name: Waipahoehoe Stream. "You're dealing with a very young environment, geologically speaking," says Rick Fontaine ofthe U.S. Geological Survey in Honolulu. And, he adds, confounding the flow of water across the featureless surface are the "interconnections with lava tubes," a largely unmapped system of underground plumbing. "The hydrology and flood hydrology of the greater Hilo area are definitely complicated," he says. On the Map According to astate-maintained website on natural hazards, a damaging flood occurs on the Big Island every two years. But the averages don't hold ,~Wzl`,~ v ~ t ` ~omm. No. S ~ f~ef. To: 1 ' ~ 1 z , . I~ef. Date 4 iJrlivers~t~ Te~rac~ for Hilo and Puna, where between 1980 and 1994, 18 flood events occurred. The most recent draft update of the Hawai i County General Plan devotes several pages to flooding. "Present drainage and flood problems are mainly due to the development of vacant lands, which are often subject to serious flooding without any commensurate, coordinated development of new drainage systems or expansion ofthe existing drainage systems," the plan states. While planners rely on Flood Insurance Rate Maps - FIRMs - developed by the federal government to steer development away from flood-prone areas, these maps are notoriously inaccurate. Current FIRM maps "are not very accurate as to the location, position, and formation of geographic and geologic attributes," the draft plan says. "Furthermore, there are many areas where there is no data to determine the flood potential." After the November 2000 flooding, the county, with Federal Emergency Management Agency support, hired a contractor to redraw FIRMS for the areas around Waiakea and Palai Streams. Typically, FIRMS indicate areas that will be underwater in a 100-year flood and a 500-year flood -floods that have a ]percent and a 0.2 percent chance, respectively, of occurring in any given year. But what constitutes a 100-year flood and how is it figured? The USGS' Fontaine described a variety of ways that hydrologists use to calculate expected 100-year peak discharges in a given stream. Federal agencies generally agree on something called alog-Peazson type III approach. "It's just a type of statistical analysis," he says, that considers stream-flow data from monitoring gauges, the watershed area that drains into a stream, and rainfall patterns within that area -among many other factors. Should one element in the equation change - if, say, a subdivision is built whose roads and houses increase the impervious azea in a watershed, or a highway is laid that interrupts natural drainage, or a forest is cut -the hydrology of the azea changes as well. And it's back to the drawing boazd to calculate peak 100-year flows. Even in the best of circumstances, determining the 100-year flood levels is more art than science. "You're trying to estimate something that's a very rare quantity," says Fontaine. "It's something that over the long term will occur just every 100 years. Of course, you could get two 100-year floods back to back." And if you are trying to predict floods for streams where sampling information is meager, the calculations aze all the more imprecise. Were all this not bad enough, estimating floods in Hilo was made tougher yet when the USGS discovered that one of its Hilo employees was submitting falsified data on stream flows over a period of several years. The employee was fired, but the loss ofyeazs of data is still being felt. Antedeluvian Records Some of the worst damage in the November 2000 flood occurred along the areas drained by the Palai and Waiakea streams. The Palai watershed had LJniversi~ Terrace not been well mapped up to that point. The Waiakea watershed had been better studied; in the 1980s, a traditional steep-walled flood control chamiel was installed from Waiakea Pond, near the coast, to the area near the University of Hawaii at HIlo. As residential subdivisions marched up the 35-square-mile watershed drained by the Waiakea Stream, the natural watercourse was walled and channelized where it passed through and along housing developments. URS Corporation, which was hired by the county to redraw flood maps - and recalculate 100-year flows -for the Waiakea and Palai watersheds has reset the clock, so to speak, on 100-year floods. The bar has been raised, and now the November 2000 flood record has come to define the new 100-year peak flood. More precisely, the flooding experienced that month was something less than what Hilo can expect to experience once every 100 years. According to Ray Lenaburg of the Federal Emergency Management Agency, "we have come up with a new 100-year [flood] dischazge, and that's what we're using in the new maps." "The old peak discharges have been superceded based on a new analysis," Lenaburg told Environment Hawai ~i in a telephone interview. The new figures, he said, came about after a consultant reviewed data from two gauges in the area and ran them through the standard log-Pearson 3 method of determining distribution. "We thought it was aone-in-100-yeaz flood," Lenaburg said of the November 2000 event, "but when we went back and looked at the data, it was less than aone-in-100 yeaz flood." To protect built-up azeas from future floods, the county and the Corps of Engineers have begun to work on a multi-year project that will lead eventually to construction of amile-and-a-half-long channel and another 1,100-foot-long levee along an existing channel. The new channels would cause the flow in Waiakea Stream to be divided into two watercourses above the Kupulau Bridge, site of some of the heaviest flooding in 2000. The two branches would rejoin at the start of the channelized Waiakea Stream, near the bridge at Komohana Street. The project, if it works out, won't provide relief for homeowners for a while yet. At a December meeting with concerned members of the public, county engineer Dennis Lee outlined the Corps' best-case timeline. From January 2003 to January 2005, the feasibility study will occur. Another year -July 2005 to July 2006 -will be required to draw up plans and specifications. Barring unforeseen delays, construction might be completed by July 2008. The estimated cost is on the order of $17 million. Besides the new work on the Waiakea Stream, the Corps of Engineers will be repairing flood channels on Alenaio Stream and the lower reaches of Waiakea Stream, channelized in 1985. Total cost of repairs is put at about $4.2 million. Double Whammy L7rl~versity Terrace If the county takes what was naturally sheet flow and directs it into channels at ever-higher elevations, won't that just make problems worse for people living downstream by adding to the volume of water in streams at lower elevations`? The question was posed to Ben Ishu of the county Department of Public Works. Ishii is the county engineer working most closely with the Corps of Engineers in designing future flood control projects. Ishii responded by pointing out that sooner or later, most sheet flow ends up in drainage channels such as Waiakea and Alenaio anyway. Directing flows to the channels upstream would not create any real problem, he said. "You could inci-rase both the vohime and peak flows ifyou induce nu~~ r~ water to come into the channel at the peak ~flola~ time. You could be producing a double whanuny." -Ri~kFoi~rt~rine, U.SC~S Yet Fontaine of the USGS had a slightly different take. "Anytime you put in an artificial channel to direct or deter runoff, you're probably reducing the time it takes the water to get to the channel," he said. "So you have a timing issue as well, now. If you have a heavy rain in the watershed, your peak flow wID occur at a certain time that has to do with how long it takes water to get into the channel. Depending on how you alter the natural timing, you could lower or raise peak flows. You could increase both the volume and peak flows ifyou induce more water to come into the channel at the peak flow time. You could be producing a double whammy, because you make that water get into the channel faster than it otherwise would." On the other hand, Fontaine added, if the planning were done right, "you could also reduce peak flows" by adding artificial channels. In the meantime, draft revisions to the Hawaii County General Plan would steer the county in the direction of greater flood plain protection and other more natural ways of protecting structures against floods. Whether the result will be anything more than exhortatory is in the face of pressure from the Corps of Engineers, the Department of Public Works, and the vast army of private and public agencies whose livelihood depends on harder solutions anyone's guess. Patricia Tummons According to Peter Boucher, who is in charge of sewers for the County of Hawaii, approximately forty percent of Hilo is on cesspools. The US Forest service is constructing a huge building neaz the University of Hawau HIlo. They were required to put in a septic system because the sewer system in that azea (near the proposed University Terrace) was inadequate. It seems to me that before we give permission to build University Terrace the County needs to invest millions of dollars and many years into expanding and improving our inadequate sewer system. CJniversity Terrace Parts of this site are in a flood plain and it also contains wetlands. To build this project as proposed, these wetlands would have to be filled in and the flood plains altered. The buflding of roads, houses, apartments and a huge shopping center with all of their accompanying parking lots, roofs and the grading and compacting of over a hundred acres of soil will definitely add to our flood problems which haven't been adequately addressed. There are many Federal and State agencies that aze involved in this area such as: USDA, NRCS, FEMA, USGS, US Army Corp of Engineers, and the DLNR. We need to consult with them before we make anymore mistakes. I believe that the criteria for establishing a Project District have not been met. Section 25-6 Criteria for Establishing a Project District: 1. Is consistent with intent and purpose of this chapter and the County General Plan 2. Will not result in a substantial adverse impact upon the surrounding area, community or region The most recent proposal for the Revised General Plan, has this property designated as rural which isn't consistent. Unless this area is totally sewered, and all run off generated from this project are contained and released gradually, the other criteria is not met. Also when the Revised General Plan is approved the criteria will not be met. I would feel better if the people of Hawaii had the say over the zoning and not primarily the developer. In conclusion, I believe this is a very complex issue that will take years of study by State, County, and Federal agencies. This involves the whole community and should have many public input meetings over a period of time. Before we make a bigger mess, why don't we clean up the messes we already have. State and Federal law say that we must clean up Hilo Bay. We must address the gigantic Hilo cesspool problems and flooding problems first. Approving this plan puts the cart miles a head of the horse. This project opens the County up to potential law suites and fines, unless we procede slowly and very carefully Respectfully, 1.. ~ '~i r Scott L Andrews