GGI completes Sediment Sampling in Los Alamos Canyon

GGI has completed sediment sampling in Los Alamos Canyon for Los Alamos National Laboratory (LANL). If you are unfamiliar with sediment sampling  and why we do it, here is my sediment sampling 101.  Stream sediments (referred to as fluvial deposits) form layers on earth surface typically composed of clay, silt, sand, and gravel, transported and deposited by water. Stream-transported sediments located outside the main stream channel are deposited during flood events. At LANL, we perform sediment sampling to calculate an inventory of contaminants within a watershed for monitoring contaminants and contaminant transport as part of the Environmental Restoration Program.

What’s interesting is we can determine the age of the sediment by calculating the age of the trees growing on the sediment. Rule of the thumb – age of sediment is older than the trees growing on top of a deposit and younger than the trees growing below a deposit. How do we determine the age of a tree? It is possible to determine the age of a tree by using dendrochronology techniques such as tree core analysis.

Now let’s take a look at a real time case study. In the figure below, the sediment should be older than the age of the Ponderosa Pine above the deposit (1969) and younger than the age of the tree growing below the sediment (1934). Therefore it can be safely concluded that the sediment was deposited between 1934 and 1969.

As part of Los Alamos Canyon sediment sampling project, sample locations were selected based on description of sediments, analysis of tree cores (dendrochronology) collected from flood-damaged trees or from trees buried by, or growing on sediment deposits.  The extent of remediation required for this site will be determined based on GGI’s detailed site investigation, including GGI’s geomorphic map of the area and the thickness of post-laboratory sediments as determined by GGI, working in conjunction with LANL.

GGI surveyed in all sample locations using a total station on 8/6/09.  Control points were also surveyed, which will allow for completion of a detailed geomorphic map, calculation of unit areas, and determination of the volume of sediments comprising each geomorphic unit.

GGI has completed several sediment sampling and contaminant transport, geomorphic mapping and soil stratigraphic studies in support of numerous environmental, archeological, water rights, spring inventory, geologic mapping and paleontological investigations. For more information please check our Geomorphology and Soils Investigations section on our website.

If you want to know more about sediment sampling and contaminant transport or want to discuss your geomorphology projects please contact me at drakos@glorietageo.com or at 505 983 5446 Ext. 108.

About GGI

Founded in 1979 in Santa Fe, NM, GGI has been providing quality professional consulting services in groundwater development, water rights, geomorphology, dairy regulatory compliance and environmental sciences. GGI serves federal, state, and municipal entities, tribal governments, private corporations, and individuals. We pride ourselves in our ability to listen to our clients’ goals and help turn these goals into successes. For more information please visit our website at www.glorietageo.com