minutes

South Bay Irrigation District

February 17, 2003

The Board of Directors of South Bay Irrigation District held a regular meeting on Monday, February 17, 2003, at the Sweetwater Authority Administrative Office, 505 Garrett Avenue, Chula Vista, California. President Wolniewicz called the meeting to order at 3:30 p.m.

ROLL CALL

Directors Present: Doud, Pocklington, Welsh, Wolniewicz and Wright

Directors Absent: None.

Others Present: General Manager Bostad, Operations Manager Mark Rogers, Legal Counsel Peggy Strand, and Board Secretary Marisa Farpón-Friedman. Sweetwater Authority staff Kevin Kasner and Jim Smyth. Also, Sweetwater Authority Director Beauchamp, Consultant Al Sorensen, and Thomas O. Keller, GEI Consultants, Inc.

PLEDGE OF ALLEGIANCE TO THE FLAG

Director Pocklington conducted the pledge of allegiance to the flag.

OPPORTUNITY FOR PUBLIC COMMENT (Government Code Section (54954.3)

There was no public present for comment.

CHAIR’S PRESENTATION

ACTION AGENDA

PRESENTATION BY KEVIN KASNER, ASSOCIATE ENGINEER, SWEETWATER AUTHORITY
Sweetwater Dam – South Spillway Investigation with the State of California, Division of Safety of Dams.

Chief Engineer Smyth gave a brief history of both Loveland and Sweetwater Reservoirs, very valuable assets to Sweetwater Authority. He also talked about the monthly surveillances in accordance with the Division of Safety of Dams (DOSD) in the State of California He noted that Sweetwater Authority has spent $2.5 million on both dams, the majority of it at Sweetwater Dam because it is older. He then introduced Kevin Kasner, who would provide a case study of the specific aspects of Sweetwater Dam. He also introduced Tom Keller of GEI Consultants, Inc.

Mr. Kevin Kasner said that it would be a rather technical presentation, and he explained the meaning of a couple of acronyms that he would be using throughout his presentation. He added that the principal goal of the Division of Safety of Dams of the State of California is to help insure that the Dams in their jurisdiction do not fail. Two of the main reports prepared by the National Weather Service over the years have been HMR-36 and HMR-58. HMR-36, which was prepared in the 1960’s, provides guidelines for determining what is the probable maximum amount of rain we could expect in a given area. HMR-58 was a significant update to HMR-36. It was prepared in the late 1990’s after a study in 1994 showed that HMR-36 was underestimating the amount of rainfall that we should expect. Basically, HMR-58 gives us increased rainfall amounts. This is especially true in the higher elevations like the watershed above Loveland. The probable maximum flood is the amount of flood that we would expect from a Probable Maximum Precipitation (PMP) event. It incorporates the amount of rainfall and several other loss factors, such as too much water being absorbed by the ground, how much water runs off due to the development, how much gets ponded, etc. The Maximum Flood is typically measured in cubic feet per second.

Mr. Kasner noted that there are three spillways on the Sweetwater dam and today he would talk mainly about the South Spillway, which has a spill elevation of 239 feet above sea level with all flashboards installed. He discussed past operating procedures that required staff to remove the flashboards prior to the approaching rainy season. Through our studies and visits with DSOD, we have determined that flood flows are not changed significantly with boards installed or removed. With us permitted to store water to 239 feet, it is not necessary to remove the boards at any time.

Mr. Kasner briefly described and showed on the screen how the spillway functions. The water level rises in the lake, crosses the crest, and fills in the channel. The water flows through the first channel until it gets to a certain elevation. Then it starts to spill over into the second channel. Another elevation that will come into play is the central Spillway, which goes across the crest of the dam. Beside it, there is a 4-foot high wall about 18 inches thick that is called the Parapet Wall, at 252 feet. Anything above that measure is overtopping the dam. That part of the dam is not designed as a spillway.

After the 1916 Hatfield flood, the South Spillway was reconstructed and operated several times through the early 1980’s. The DSOD 1981 report said that the spillway was in great shape. In 1990, Sweetwater Authority had consultant engineers inspect the South spillway. They recommended rather extensive repairs, along with some repairs to the North side and other areas. This was mainly the result of several large spills that we had in the 1980’s.

Mr. Kasner displayed pictures showing deterioration on the grillage structure and around the deflector veins, as well as cracking in the floor of the spillway. This is an area of concern because water comes up through the floor of the Spillway under high reservoir levels and causes much of the deterioration.

In 2001, URS Greiner did a report for Sweetwater Authority. They advised us to determine whether it is most appropriate to repair the spillway and fix the concrete, reconstruct the entire Spillway, or perhaps abandon the spillway and see if the North and Central spillways can handle the flood that we could expect. In 2002, Sweetwater Authority retained Tom Keller and GEI Consultants to perform an evaluation. Mr. Kasner explained in detail the analysis process. He displayed pictures showing the area above the Parapet Wall. Under HMR-36, the calculated overtopping of the Parapet was 3-4 inches for about two hours with a flow of 72-73,000 cubic feet per second. DSOD has determined this is an acceptable level of overtopping.

GEI Consultants evaluated the dam as a whole and developed models for the spillways within rain curves. These curves allow the computer to calculate how much water can get over the Spillway in a certain amount of time. They took this model and the flood that, according to HMR-36 we should be able to pass with a certain amount of overtopping, and they ran it through their model to make sure their numbers are correct and the rating curves that were developed for the Spillways were valid. They determined a new flood using HMR-58 and then routed it through the model to determine a new level and duration of the overtopping. GEI Consultants have used the same loss rates in their analysis by assuming that, in the last 30 or 40 years, the amount or runoff that we would expect has not changed in the upper Watershed. This results in an overtopping of the Parapet by almost 2 feet for almost 5 ½ hours. HMR-36 was .35 feet for 2 hours with a peak flow of 93,000 cubic feet per second. Basically, the structure cannot pass the water through it safely.

After meeting with GEI Consultants, Sweetwater staff realized that there were some potential issues that needed to be discussed with DSOD. They met with DSOD staff in January to find out what their position was on HMR-58 versus HMR-36. The findings were that if we are repairing the dam, HMR-36 is still the governing flood at this time and they are not requiring the dam owner to calculate the precise HMR-58 flood and retrofit the structure to meet that design flood. They do not know what they are going to do two or five years from now; however, if any new construction is undertaken and we opt to replace the boards with a new permanent structure, we are then subject to HMR-58 and must design for the much larger flood.
As a result of the meeting with DSOD staff, they understand that HMR-58 is a potential problem for the existing dam and have requested a plan to address the issue along with erosion and spillway analyses. We have begun the planning process with GEI. They have done some preliminary field reconnaissance and are preparing alternative approaches. Additional issues beyond the dam, spillways, and parapet that need to be addressed include the South dike and the Urban Runoff Diversion System. Mr. Kasner stated that next year’s budget for the Engineering Department will include funds for a full evaluation of the PMF of Sweetwater and Loveland dams including DSOD review.

ITEMS TO BE ADDED, WITHDRAWN OR REORDERED TO THE AGENDA
(Government Code Section 54956.5)
There were none.

APPROVAL OF MINUTES

Director Doud made a motion, seconded by Director Wright, that the Board approve the minutes of the regular meeting of January 20, 2003. The motion carried.

APPROVAL OF DEMANDS AND WARRANTS

Director Doud made a motion, seconded by Director Wright, that warrant numbers 9944 through 9956 be approved. The motion carried.

NEW BUSINESS

LAFCO – Call for nominations to the Local Agency Formation Commission and the Special Districts Adivisory Committee.

Director Welsh made a motion, seconded by Director Wright, that the Board nominate James “Ski” Wolniewicz to the Local Agency Formation Commission and the Special Districts Advisory Committee. The motion carried.

APPROVAL OF DIRECTORS’ ATTENDANCE AT MEETINGS & FUTURE AGENDA ITEMS

A. Director Wright made a motion, seconded by Director Wright, that the Governing Board approve per diem for directors who attended the Tour of Sweetwater Authority facilities on January 29, 2003. The motion carried.

B. Director Doud made a motion, seconded by Director Wright, that the Governing Board approve per diem for directors who attended the State of the County Address on February 5, 2003. The motion carried.

REPORT OF TREASURER

Ms. Avery said that interest rates are still at about 1.7 percent.

REPORT OF LAFCO SPECIAL DISTRICTS ADVISORY COMMITTEE MEMBER

Director Wolniewicz said that there was no meeting. He stated that he had been requested by LAFCO to attend the next meeting and that he will be sitting on the Review Board.

REPORT OF LAFCO SPECIAL DISTRICTS REGULAR MEMBER

President Pocklington said that they had a meeting in February with a long agenda, but there was nothing of real value to the South Bay.

REPORT OF SAN DIEGO COUNTY WATER AUTHORITY REPRESENTATIVE

President Pocklington had no news regarding the IID Transfer. He commented that they still have a gag order in Sacramento and he is not sure if they will meet again this week. We may hear more about it Thursday at the Board meeting.

DIRECTORS’ COMMENTS

Director Wolniewicz handed out a report reflecting the amounts received for per diem this year. He would like to discuss at the next Board meeting the per diem issue. He noted that after the first two meetings, per diem is only $100. Since he is elected to the California Special Districts Board, he thinks it is unfair that he is carrying 50 percent of the load in contributions to save South Bay.

CLOSED SESSION

At 4:17 p.m. the meeting went into closed session to discuss a potential litigation in accordance with Government Code § 54956.9. There were no minutes taken and the session was not tape-recorded.

At 4:26 President Pocklington declared the meeting in open session and there was no reportable action.

13. ADJOURNMENT

With no further business before the Board, President Pocklington adjourned the meeting at 4:27 p.m., to the hour of 3:30 p.m., on March 17, 2003.