Location

St. Louis, Missouri

Session Start Date

6-1-1993

Abstract

The Upper Mun Dam located In Nakom Ratchaslma, the Northeastem Province of Thailand, intercepts a catchment area of 454 sq. kms. It is a zone earth dam with 32.7 meters of maximum height and 880 meters in length. The foundation strata comprises alluvial deposits overlying sandstone and siltstone. The chute spillway is designed for probable maximum flood of 950 m3/sec. and the outlet conduit is 1.84 by 1.84 meters caters for a maximum outflow of 11.2 m3/sec. No foundation treatment was carried out except cement grouting beneath the spillway and the outlet. The dam was completed on May 1989. The maximum storage for the first year Impoundment was 33.7 million m3 with water level at the elevation 212.32 meters. The river bed elevation Is 205.00 meters. In October 1990, the water level rose to nearly full reservoir level at the elevation 220.42 meters with the storage volume of 131.8 million m3 due to heavy rain fall when concentrated seepage was noticed at two locations downstream of the toe. At one of the two locations, the leakage caused a cave-In of the down stream slope of the embankment which plugged and stopped the leakage. At the other location, concentrated leak reached its peak of about 5 m3/sec. and resulted in progressive erosion of embankment toe. Many countermeasures to save the dam from felling were deployed. Earth moving equipments were used to push riprap as well as embankment material continuously into the leakage locations. The reservoir level was lowered through the outlet and siphoning over the spillway crest. The operation was continued for 3 weeks before the leakage was brought down to a few litre/sec. of clear water. During this Incident 57 villages involving over 13.000 residents had to be evacuated. After the reservoir was emptied in a few months later, an Intensive Investigation program was carried out to look into the cause that lead to the leakage of the dam.

Department(s)

Civil, Architectural and Environmental Engineering

Appears In

International Conference on Case Histories in Geotechnical Engineering

Meeting Name

Third Conference

Publisher

University of Missouri--Rolla

Publication Date

6-1-1993

Document Version

Final Version

Rights

© 1993 University of Missouri--Rolla, All rights reserved.

Document Type

Article - Conference proceedings

File Type

text

Language

English

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Jun 1st, 12:00 AM

Leakage at Upper Mun Dam

St. Louis, Missouri

The Upper Mun Dam located In Nakom Ratchaslma, the Northeastem Province of Thailand, intercepts a catchment area of 454 sq. kms. It is a zone earth dam with 32.7 meters of maximum height and 880 meters in length. The foundation strata comprises alluvial deposits overlying sandstone and siltstone. The chute spillway is designed for probable maximum flood of 950 m3/sec. and the outlet conduit is 1.84 by 1.84 meters caters for a maximum outflow of 11.2 m3/sec. No foundation treatment was carried out except cement grouting beneath the spillway and the outlet. The dam was completed on May 1989. The maximum storage for the first year Impoundment was 33.7 million m3 with water level at the elevation 212.32 meters. The river bed elevation Is 205.00 meters. In October 1990, the water level rose to nearly full reservoir level at the elevation 220.42 meters with the storage volume of 131.8 million m3 due to heavy rain fall when concentrated seepage was noticed at two locations downstream of the toe. At one of the two locations, the leakage caused a cave-In of the down stream slope of the embankment which plugged and stopped the leakage. At the other location, concentrated leak reached its peak of about 5 m3/sec. and resulted in progressive erosion of embankment toe. Many countermeasures to save the dam from felling were deployed. Earth moving equipments were used to push riprap as well as embankment material continuously into the leakage locations. The reservoir level was lowered through the outlet and siphoning over the spillway crest. The operation was continued for 3 weeks before the leakage was brought down to a few litre/sec. of clear water. During this Incident 57 villages involving over 13.000 residents had to be evacuated. After the reservoir was emptied in a few months later, an Intensive Investigation program was carried out to look into the cause that lead to the leakage of the dam.