Laserfiche WebLink
o~s~na/Lnba 14:13 9704542647 <br />July 20, 2004 <br />Rollin Consuking <br />Bd0 Eagle Drive <br />Eaton, Colorado 80815 <br />Attn: Mr. Ken Rollin <br />Re: Gravel Evaluation <br />Northwest of Weld County Roads 18 and 25 <br />Weld County, Colorado <br />Terracon Project No. 21035117 <br />Mr. RolUn, <br />l~+~rr~con <br />GonauRinp Enplna~rr i Behntlala <br />1289 Fiial Avanun <br />Pa4I OI9ca BOM t744 <br />CiroeleY. Cobrado 80832.7744 <br />Phone 970.351.0480 <br />Fay 970.353.8839 <br />www,larrawn.oom <br />Please accept this letter as an~addendum'to our original Geotechnical Engineadng Report for the <br />above referenced project in Weld County, Colorado. The purpose for this addendum Is to provide a <br />revised assessment of the estimated overburden antl sand and gravel volumes and gravel sizes <br />based upon additional test borings drilled at the site. <br />Four additional test borings were drilled at the site on June 30, 2004. The borings ware drilled to <br />approximate depths of 29 to 33 feet at the locations shown on the attached Site Plan. All borings <br />were advanced with struck-mounted drilling rtg utilizing 8-inch diameter solid stem augers. The <br />borings were k)Cated in the field by the owners. Lfthologic logs of each boring were recorded by the <br />field engineer during the drilling operations. At selected intervals, samples of the subsurtace <br />materials were taken from auger cuttings. Groundwater conditions were evaluated in each boring at <br />the time of site exploration. <br />Evaluation <br />Based on the additional test borings drilled at the site by Terracon, we estimate approximately <br />2,655,000 cubic yards of sand and gravel is contained within the boundaries outlined on the site plan. <br />Appro>amatety 714,000 wbic yards of overburden would have to be removed to obtain the sand and <br />gravel in this area. The above quantities are based on the average thickness of overburden and sand <br />end gravel obtained from the current test borings in atltlitbn to the original test borings drilled by <br />Terracon as outlined in our site plan and on the area boundary based on the Information provided by <br />the cBent. Because of physical property boundaries such as roads and properly tines, the quantity that <br />can be removed is less than what is stated above. Based on the current test borings in addition to the <br />original test borings, the average overburden thickness is approximately B fret and the average sand <br />and gravel thickness is approximately 22 feet. This gives a ratio of sand and gravel ~ overburden of <br />approximately 3.7 to 1. <br />Based qn our visual observation during drilling and the limited laboratory fasts run on auger samples, <br />the granular materials encountered consist of good quality aggregate suitable for use in construction <br />materials, Cobbles (3 inches in diameter or larger materials) were not noted within the granular <br />stratum. However, estimated gravel sizes are limited by the sampling method utilized and era based on <br />ROLLIN PAGE 02 <br />Dallvtlinp Succeaa for Glkrda and EmDloYaaa 9inca lips <br />Mon Than 80 Oelces Natlomvlds <br />