FLOOD11630 ‎(2)‎

• County: Statewide
• Basin: Arkansas
• Title: Post Flood Assessment Report - Arkansas River
• Date: 9/15/1999
• Floodplain - Doc Type: Flood Documentation Report

valley of the Purgatoire River was also being monitored daily. Based on past performance of this
dam, no problems were anticipated in these seepage areas, and none occurred. Th~e inflow
continued to fall on May 6, 1999 from approximately 900 c.f.s. to 700 c.f.s. Howc;ver, the dam
continued to store all inflows and on May 13, 1999, with the reservoir continuing '~fo climb and
calls for irrigation releases not expected for several week.5, it was projected that th~~ reservoir
would exceed the record pool. The previous record pool elevation was 6,222.67 fe;et set on April
26, 1983. On May 20, 1999 the pool reached elevation 6,221.76 feet with an inflow of less than
450 c.f.s. Irrigation releases began the next day at 60 c.f.s. After reaching an inteiinediate record
peak a subsequent rainstorm induced a new record pool eievation of 6,230.24 feet at 0700 hrs on
July 6, 1999. The project performed well throughout the :flood event.
Fort Lyons Levee: T'he Fort Lyon levee is part of the John Martin Project. The le~~ee was
constructed along with the dam in the early 1940's to protect the existing VA Hos~rital from high
pools in John Martin Reservoir. Many of the VA Hospital's vital infrastructure fea.tures, as well
as the hospital itself, are protected by the levee from even low-level flood pool res~rvoir
elevations. The bottom of the flood pool is elevation 3,851 feet while the hospital's power plant,
water supply pumps, and sewage disposal system are located at about elevation 3,~50 feet.
General contour maps indicate that the first floor elevation of the hosp~tal's main building is at
approximately 3,865 feet.
On May 12, 1999 numerous sand boils were reported along a 1,200-foot long sectiu~n of the Fort
Lyon VA Hospital levee. The top of the levee is at elevation 3,875 feet while the l~ndside toe in
the azea of the sand boils is about 3,844 feet. The two largest sand boils had a clear center about
12 inches in diameter and these sand boils had cones 5 feet in diameter and 18 inch.es high.
These sand boils were located within a drainage ditch that runs pazallel to the levee: on the
landside. The ditches carry interior drainage to a sump pump, which takes the watE;r collected
into the reservoir. The project staff at John Martin was monitoring the situation the:re and
reported no unusual amounts of material being discharged at the boils.
Corps of Engineers personnel from the Albuquerque District left early on the morn:ing of May
12, 1999 for John Martin Dam to inspect the sand boils. ~y this time the John Maztin Project
Office had started to repair a 30 foot by 30 foot area with the two largest sand boils using a
supply of filter fabric and fill maintained at John Martin Dam to perform emergency repairs. By
the following moming the project office had stabilized three areas by constructing ~-ing dikes
around the sand boils. Project office personnel remained on site to perform additio:nal work as
required.
In the afternoon of May 12, 1999 the section of the Fort Lyon VA Hospital levee where the sand
boils had formed was inspected and it was determined that the situation posed no ttxreat.
Nevertheless, as a prudent precaution, it was recommended that a contract be issueci to build a
stabilizing berm on the landside of the levee. The berm would be constructed alon€; the existing
road embankment that had been placed by the VA. The arnount of fill required vari:ed from 4 to
10 feet thick. The repair work consisted of placing material to establish a working ~ase, and
placement of filter material; then building an earthfill embankment 10 to 15
Chapter 3- Flood ofApri129, 1999
Post Flood Assessment Report ~~ 23 Draj't Revised G-9/09/99