Cris Alexander, CPBE, AMD, DRB
Crawford Broadcasting Company
As we head into the heat of August, the cool rains of May and June are a distant memory, but the evidence they left behind is still apparent in many locations. One such location is Crawford’s KLVZ (810) daytime site just north of Brighton.
That site is on the east bank of the South Platte and is unquestionably in the flood plain. When we rebuilt the site a few years ago with a new prefab (think “cellular”) building, we had to get a flood certificate showing the MBFE (minimum base flood elevation) and then build one foot above that. It’s a good thing, too, because on several occasions since the rebuild, flood waters have covered the site.
As May turned to June, the site was mostly under water. The water wasn’t flowing, so it wasn’t really the river out of its banks so much as it was overflow from adjacent quarry sloughs and saturated ground. As the water covering the site receded, however, the fun was just beginning as the South Platte was rising from upstream runoff.
|The new South Platte River channel at the SW corner of the KLVZ property. The breach that resulted in the flood is in the center background of the photo. The fence marks the KLVZ property boundary, what used to be dry ground some ten feet higher.|
The KLVZ site has quarry operations adjoining it on the south and east sides. On the south side, the quarry operator dug out a slough to provide a place to pump water out of the mining operation. When constructing the slough, the quarry operator built a 20-foot berm across most of the south side of the KLVZ 15-acre property. This berm has provided a great and safe place to target shoot over the years!
As the site dried out and the river rose, it broke through the narrow spit of land between the river and the quarry slough. The swollen South Platte roared into the new channel, around our property on the south and following the slough around on the east. It washed out Weld County Road 6 where it crossed a drainage channel adjacent to the slough, leaving a 20-foot gap in the roadway with deep, fast water running below. The South Platte had forked right at the southwest corner of the KLVZ property and was running in two more or less equal flows and channels on either side of the site. The new channel rejoined the old a thousand feet or so north of the site, creating “Crawford Island.”
The river ran like that for most of July, and as the flow settled down into something approaching normal levels, it became clear that the new channel on the east side of the site was a permanent new channel. The breach in the riverbank had been scoured to a depth lower than the river bottom itself and with a width equaling if not exceeding that of the main river channel, so half if not more of the flow was permanently flowing through the new channel.
|The same view after damming of the breach. The new dam is visible in the background. The sandy bottom is 10-12 feet below the site grade.|
The good news for us was that the KLVZ site remained (relatively) high and completely dry, unaffected by its new island status. The bad news was that we had to take a circuitous route down miles of washboard dirt farm roads to get into the site from the west; the 20-foot gap in the pavement on WCR6 was a real problem for accessing the site. The other bad news was that the river flow was eating away at the southwest corner of the KLVZ property. We could see a foot or two of our land disappearing into the muddy water every day.
Then in late July, a contractor showed up and started building a dam across the breach. They brought in truckload after truckload of recycled concrete and dumped it into the breach. With that base in place they started bringing in dirt, hundreds of tons of the stuff. Within a few days, the new river channel was down to a trickle and we were able to get our first look at what had been left behind – a ten-foot-deep, 20-foot-wide and 100-foot-long area that used to be our property. The perimeter fence posts were dangling by the fence wire some 20 feet out into what had been the new channel. The ends of several ground radials could be seen trailing away from the cut bank into the sandy bottom some ten feet below. We lost over 2,000 cubic yards of soil.
Aside from relocating the perimeter fence in that corner back up onto solid ground and doing our best to bury those radial ends in the sand, the KLVZ site is no worse for wear. The station stayed on the air throughout both the initial flood and the river split. We lost power for a few minutes while Xcel relocated a pole that had been swallowed by the new channel, but the station was able to operate from the night site while the power was out.
Now we have to wait on Weld County to rebuild that section of WCR6. We’re told that it will be November. I guess it could be worse!
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