Laserfiche WebLink
• i • <br />Trinidad Basin Surface [/ater <br />1. A general Boater balance discussion should be included that describes <br />the rainfall, runoff, evapotranspiration, and infiltration relationships of <br />the general area. This information will be useful in our assessment of surface <br />flow characteristics and recharge significance. <br />2. As was mentioned in the Division's adequacy letter of March 25, 1982, all <br />ponds greater than 10 feet in height must be approved by the State Engineer's <br />office. However, TBM should note that this height is measured from the <br />bottom of the emergency spillway to the original ground surface at the embank- <br />ment~centerline. It does not include the excavated or .incised elevation, but <br />rather the original ground elevation. faith this definition in mind, TBM may <br />wish to revise their list of ponds needing SEO approval. <br />3. The applicant has stated that they will compensate for embankment settle- <br />ment by increaseing dam heights by 0.5 feet if acceptable to the Division. <br />Since all dams are at or below 10 feet, this increase in height would be about <br />S%, which is what Rule 4.05.6(8)(c) requires. Their proposal is, therefore, <br />acceptable. <br />4. For all new ponds proposed to be constructed by TBM, will anti-seep collars <br />and cut off trenches be utilized? <br />5. Rule 4.05.6(3) requires that a non-cloyyiny dewatering device or conduit <br />spillway be placed at the 100^a sediment storage Level. There are several reasons <br />for this requirement: <br />a) This dewatering insures that there will always be storaye available <br />for the 10-year, 24-hour event without displacement; <br />b) It allows the pond to function as a sedimentation basin not as an <br />impoundment; <br />c) It limits the amount and duration of embankment saturation which might <br />insure a more stable structure; <br />d) It allows the ponds to be built smaller since t:he design storm event <br />may be routed through the pond by storage routing; <br />e) It minimizes disturbance to the natural stream flows by allowing the <br />runoff to flow through the structure, even though the peak flow will be <br />attenuated; and, finally, <br />f) It reduces the amount of water wasted by evaporation. <br />This final reason is possibly the most important. 4Jatez' in this State is highly <br />valued because demand frequently exceeds supply. As a z'esult, our Division <br />cooperates with the Colorado Division of lJater Resources to ensure that as little <br />water as practical is wasted. In addition, State [9a ter Law prohibits the <br />impounding of 2 acre-feet or more of water unless storage and water rights have <br />been obtained. Our Division recognizes that most of your ponds are small, but <br />the cumulative effect of storing water i.n all 35+ ponds may be significant to <br />the IocaZ watershed and actual or potential downstream users. <br />s <br />