|
10/13/2008 Ike Update
On Tuesday, October 7th, the SJRA Board of Directors received a presentation from engineers with Freese & Nichols, Inc. regarding alternatives for repairing and/or upgrading the dam and then voted to approve an engineering contract and work order to develop plans and specifications for the selected repair.
Janis Murphy, P.E., with Freese and Nichols, Inc., estimated that the cost to repair the damaged areas of the dam to pre-Ike condition would be approximately one million dollars. This spot repair would cover slightly less than 1,500 feet of the 12,000-foot length of the dam and would involve the use of a larger, heavier rock similar to that used in the Hurricane Rita repairs and which proved to be more resistant to wave action than the original rock used in construction of the dam in the early 1970’s. It is anticipated that the cost of the repair would be eligible for at least 75 percent FEMA reimbursement.
Other repair/upgrade alternatives considered by the Board included: 1) replacement of all the riprap on the upstream face of the dam with soil cement above the normal pool water surface elevation; 2) flatten the slope of the riprap face above the normal pool water surface elevation from 2:1 to 2.5:1 by narrowing the crest of the dam; and 3) flatten the slope of the riprap face above the normal pool water surface elevation from 2:1 to 3:1 by installing a short retaining wall at the top of the dam. All of these upgrade alternatives were approximately 10 times the cost of repairing the dam to pre-Ike conditions using larger rock.
The Board elected to proceed with the spot repair using larger rock. This repair can proceed quickly and take advantage of current FEMA post-disaster funding. The Board can still consider future upgrades to the entire structure under FEMA’s Pre-Hazard Mitigation Program.
Impacts on Lake Level
At this time, it has not been determined if any further lowering of the lake level will be necessary to complete the spot repairs. This analysis is part of the engineering design of the repair. The current schedule is for engineering design to be completed in November, bids to go out in December, contract award to take place at the January board meeting, and a notice to proceed to be issued in late-January. It is estimated that the actual repair work would take eight to twelve weeks. We are attempting to expedite this schedule, but these are the current estimated dates.
IF any further lowering of the lake level is required to do the repairs, this would not happen prior to the issuance of a notice to proceed, and prior to that time an aggressive public information campaign would be undertaken to inform boat owners and lake area residents.
10/01/2008 Ike Update
On Thursday, September 25th, after completing a gradual, one week lowering of the lake level from 201 MSL to 200 MSL, SJRA personnel and engineers from Freese & Nichols, Inc., conducted a second analysis of the dam and documented areas of riprap and blanket material that were damaged or exposed during Hurricane Ike. Freese & Nichols is currently studying various alternatives for repairing and/or upgrading the dam, and it is anticipated that they will present their findings to the SJRA sometime within the next week or two.
At this time, the SJRA does NOT have any immediate plans to lower the lake further to conduct additional inspections or repairs. Right now we are holding at approximately 200 MSL until Freese & Nichols completes its study. After the engineers present their report, a repair method will be selected, and then engineering design, bidding, and contractor selection would begin. IF any further lowering is required to do the repairs, and IF the amount of necessary lowering is significant, then at that time an aggressive public information campaign would be undertaken to inform boat owners. But right now, there is no immediate need for boat owners to move their boats.
We will continue posting information on this web site in an effort to provide the public with up-to-date, accurate information. We are also preparing a modification for this web page that will allow you to register an email address so that we can send you periodic email updates.
Press Release Number 4
HURRICANE IKE PRESS RELEASE #4
9/18/2008, 3:00 PM
SJRA Beginning Gradual Release to Lower Lake Conroe One Foot
The San Jacinto River Authority reports that it has begun making a limited release of water from Lake Conroe to lower the lake level one foot so that additional assessments can be made of the areas along the face of the dam that were damaged by waves during Hurricane Ike. Downstream river levels were verified through the Coastal Water Authority, the operator of the Lake Houston dam, and then a limited release of 2,000 cubic feet per second was initiated on Thursday afternoon, September 18.
The lake level at the start of the release was approximately two inches over the normal pool level of 201 MSL. The SJRA intends to lower the lake one foot to 200 MSL, which is the same level of the lake just prior to Hurricane Ike. At such a slow release rate, it will take approximately one week to achieve a one foot drop in lake level.
After initial assessments have been completed, it is possible that additional lowering may be required. Lake users are advised to monitor the SJRA website (www.sjra.net) and local media for future announcements regarding the lake level. At this time, Lake Conroe is open to vessel traffic, however boaters should use extreme caution due to large amounts of floating debris.
Press Release Number 3
HURRICANE IKE PRESS RELEASE #3
9/15/2008, 6:00 PM
Current Lake Conroe conditions. The water level in Lake Conroe is currently at 200.95 feet above mean sea level, which is just under one inch below normal pool level of 201 MSL. There were no releases of water from Lake Conroe during Hurricane Ike. The lake was one foot below normal pool level prior to the storm, and the water level came up just over 11 inches, but no releases were required.
Minor damage to dam. As reported previously, the dam has sustained some wave-related damage to the rip rap covering on the upstream face. This damage does not present any danger to the safety or integrity of the dam. The damage incurred during Hurricane Ike is similar in nature to the type of damage experienced during Hurricane Rita, but engineers and SJRA officials have determined today that the damage is not as extensive as the damage caused by Hurricane Rita.
Future releases of water to further assess hurricane damage. Engineers have determined that it will be necessary to gradually lower the lake level to conduct further assessments of the damage to the face of the dam and to begin preparing a remediation plan. No releases for inspection purposes will be made until downstream water levels have receded, and then releases will only be made in a safe and gradual manner. At this time, it is estimated that the lake level will be lowered approximately one foot beginning no earlier than Thursday, September 18th. This will put the lake level at 200 MSL, which is only one foot below normal level.
Lake front owners are advised to take appropriate action with regard to their boats and watercraft as soon as lake conditions permit. At this time, Lake Conroe is still closed to all vessel traffic other than emergency vessels, however, SJRA officials will consider opening the lake to non-recreational vessel traffic when conditions are deemed safe to allow boat owners to attend to their vessels.
Press Release Number 2
HURRICANE IKE PRESS RELEASE #2
9/13/2008, 4:00 PM
WATER AND SEWER ADVISORY FOR THE WOODLANDS, TEXAS
Due to widespread power outages, all drinking water plants and pump stations in The Woodlands are currently running on auxiliary power. Water pressure is being maintained, but at lower than normal pressures. All residents are instructed to conserve water by limiting water use to only essential public health uses, such as drinking and cooking.
The majority of sanitary sewer lift stations in The Woodlands are also without power or on auxiliary power, therefore please limit use of sanitary facilities, if possible.
Press Release Number 1
HURRICANE IKE PRESS RELEASE #1
9/13/2008, 1:00 PM
While there is no threat to the integrity or structure of the Lake Conroe dam, the San Jacinto River Authority reports that some damage has occurred to the rip rap covering on the upstream face of the dam in limited areas. This damage does not represent any danger to the safety of the dam.
As the eye of Hurricane Ike traveled northward along I-45 through the eastern half of Montgomery County, the Lake Conroe area experienced sustained, hurricane force winds coming directly from the North at approximately 80 to 90 miles per hour. These North winds passing over the length of the lake caused five to six foot waves to break against the face of the dam causing some erosion of the protective rip rap layer in certain limited areas.
The damage incurred during Hurricane Ike is similar in nature to the type of damage that occurred during Hurricane Rita. Engineers and SJRA officials have already begun assessing the extent of the damage so that a remediation plan can be developed, but it should be noted that there is no threat to the safety of the dam and no danger of dam failure.
At the time of Hurricane Ike’s approach, the water level of Lake Conroe was one foot below normal pool level, meaning that thus far the lake has been able to absorb the rainfall that has occurred and no release of water through the gates has been necessary. However, some rainfall is still forecasted to occur throughout the next day or two, and it could become necessary to begin routine releases if the lake level rises above the normal pool level. At this time, the lake is still six to eight inches below pool level.
In the coming days after the storm has passed and flood waters downstream have begun receding, it will likely be necessary to gradually lower the lake level to assess the damage to the face of the dam. This is similar to the action that was necessary following Hurricane Rita. Lake front owners are advised to take appropriate action with regard to their boats and watercraft as soon as lake conditions permit. |
San Jacinto River Authority
