Sand and Gravel
Sand and Gravel
Sand and gravel are essential for supporting and maintaining economic development throughout the State of Delaware. Sand and gravel are used primarily for aggregate in the production of concrete for residential, industrial, and commercial buildings, and bridge and highway construction; fill for road beds and foundations; beach replenishment; water and sewer systems; pipeline construction; drainage around foundations; and in the construction of drain fields for on-site wastewater disposal fields.
There are relatively large quantities of sand and gravel in Delaware. Most of these resources are from the Columbia Formation which forms a sheet of sand covering most of the Coastal Plain of Delaware; however, the quality and quantity of materials in Delaware are not evenly distributed. There are additional quantities of sand resources in the Delaware Bay and estuary and off the Atlantic Coast of Delaware that have been mined for beach replenishment. Geologic maps and reports prepared by the Delaware Geological Survey can be used to target promising areas for exploration as well as to eliminate unpromising areas.
The U.S. Geological Survey in cooperation with the Delaware Geological Survey compiles sand and gravel
production information through mailings of questionnaires to major sand and gravel producers throughout
Delaware. Information is compiled yearly and is presented in U.S. Geological Survey publications entitled
"Delaware Mineral Industry Surveys." At this time there are at least 11 major sand and gravel production
operations in Delaware. General locations are shown on the map. The DGS estimates that the amount of
sand and gravel produced from Delaware's natural resources is higher than previously reported by the
U.S Bureau of Mines and currently by the U.S. Geological Survey. Reasons for this include (1) not all
major producers report production; (2) agencies or companies that produce from pits for their own use
do not necessarily report production; (3) many operations that mine relatively small amounts of sand
and gravel are not contacted and therefore do not report production; and (4) production of sand from
offshore areas is not included in the figures. For example, in 1992, approximately 2.5 million short
tons of sand and gravel, valued at $8.6 million, was produced in Delaware. That information was
reported to the U.S Bureau of Mines by 7 companies operating 10 pits. According to the Delaware
Department of Transportation during the same year about 5.9 million short tons of "borrow/soil"
was produced from 18 pits for use in the construction of State Route 1. This production was in
addition to the 2.5 million short tons reported to the U. S. Bureau of Mines. Results of the
surveys for the period 1987-1996 are shown on the graph. During the period 1987-2006, the
publicly reported annual production has ranged from 1.9 million to 8.4 million short tons.
The estimated value of the material during this period ranged from 5.1 million to 28.4 million
dollars (graph). It is interesting to note that the cost for a short ton of sand and gravel has more than doubled from 1993 to 2008.
In addition to sand and gravel produced in Delaware, Delaware also imports shipments of aggregates, principally crushed stone, from adjacent states for use in construction projects.