Question: Who constructed and operated Basin F at the Rocky Mountain Arsenal through late 20th century?

Context paragraphs:
Grasshopper Glacier (Montana): Grasshopper Glacier is in the Beartooth Mountains, Custer National Forest, Montana, U.S.  The glacier is within the Absaroka-Beartooth Wilderness, a part of the Greater Yellowstone Ecosystem.  Grasshopper Glacier is approximately .20 mi long and .25 mi wide.  Starting at a point more than 11300 ft above sea level, the glacier originally was more than 5 mi long but has receded significantly since first researched in the early 20th century.  As of 2007, the glacier consists of several smaller glaciers, each occupying a different north-facing cirque.  Grasshopper Glacier was named for the tens of millions of grasshoppers (locusts) that have been found entombed in the ice, some for hundreds and perhaps thousands of years.  Many of the grasshoppers are of species that are now extinct, and their high level of preservation allowed early researchers to send some specimens to entomologists for identification.  During this research it was discovered that some of the grasshoppers were of the extinct species "Melanoplus spretus" (Rocky Mountain locust), known to have existed at least up to the beginning of the 20th century.

M34 grenade: The M34 White Phosphorus Smoke Grenade or "Willie Pete" was a chemical grenade manufactured by Rocky Mountain Arsenal from the late 1950s and used by U.S. forces during the Vietnam War and was also used during the First Gulf War.  The M34 WP Grenade replaced the World War II M15 WP grenade.  The M34 could be fired from a rifle grenade launcher using M2-series grenade launching adapters, which the groove around the tapered base allowing the adapter arms to grasp it.  The M15 could not be fired as a rifle grenade.  The M34 had a segmented body to allow for a better hand grip and to identify it as a casualty-producing grenade, even though it did not fragment.  The smooth-bodied M15 was sometimes assumed to be a burning type smoke grenade as the AN-M8 white smoke and resulted in injuries.

Dunster Castle: Dunster Castle is a former motte and bailey castle, now a country house, in the village of Dunster, Somerset, England.  The castle lies on the top of a steep hill called the Tor, and has been fortified since the late Anglo-Saxon period.  After the Norman conquest of England in the 11th century, William de Mohun constructed a timber castle on the site as part of the pacification of Somerset.  A stone shell keep was built on the motte by the start of the 12th century, and the castle survived a siege during the early years of the Anarchy.  At the end of the 14th century the de Mohuns sold the castle to the Luttrell family, who continued to occupy the property until the late 20th century.

Basin F: Basin F was constructed by the United States Army in 1956 at the Rocky Mountain Arsenal, to provide for the disposal of contaminated liquid wastes from the chemical manufacturing operations of the Army and its lessee Shell Chemical Company.

Bnei Menashe: The Bnei Menashe (Hebrew: בני מנשה‎ ‎ , "Sons of Menasseh") are a small group within the indigenous people of India's North-Eastern border states of Manipur and Mizoram; since the late 20th century, they claim descent from one of the Lost Tribes of Israel and have adopted the practice of Judaism.  The Bnei Menashe are made up of Mizo, Kuki and Chin peoples, who all speak Tibeto-Burman languages, and whose ancestors migrated into northeast India from Burma mostly in the 17th and 18th centuries.  They are called Chin in Burma.  In the late 20th century, Israeli Rabbi Eliyahu Avichail of the group Amishav named them Bnei Menashe, based on their account of descent from Menasseh.  Most of the peoples in these two northeast states, who number more than 3.7 million, do not identify with these claims.

Rocky Mountain Horse: The Rocky Mountain Horse is a horse breed developed in the state of Kentucky in the United States.  Despite its name, it originated not in the Rocky Mountains, but instead in the Appalachian Mountains.  A foundation stallion, brought from the western United States to eastern Kentucky around 1890, began the Rocky Mountain type in the late 19th century.  In the mid-20th century, a stallion named Old Tobe, owned by a prominent breeder, was used to develop the modern type; today most Rocky Mountain Horses trace back to this stallion.  In 1986, the Rocky Mountain Horse Association was formed and by 2005 has registered over 12,000 horses.  The breed is known for its preferred "chocolate" coat color and flaxen mane and tail, the result of the relatively rare silver dapple gene acting on a black coat, seen in much of the population.  It also exhibits a four-beat ambling gait known as the "single-foot".  Originally developed as a multi-purpose riding, driving and light draft horse, today it is used mainly for trail riding and working cattle.

Tabloid talk show: A tabloid talk show is a subgenre of the talk show genre which emphasizes controversial and sensationalistic topical subject matter.  The subgenre achieved peak viewership during the late 20th century.  Airing mostly during the day and distributed mostly through television syndication, tabloid talk shows originated in the 1960s and early 1970s with series hosted by Joe Pyne, Les Crane and Phil Donahue; the format was popularized by personal confession-filled "The Oprah Winfrey Show", which debuted nationally in 1986.  Tabloid talk shows have sometimes been described as the "freak shows" of the late 20th century, since most of their guests were outside the mainstream.  The host invites a group of guests to discuss an emotional or provocative topic – ranging from marital infidelity to more outlandish topics – and the guests are encouraged to make public confessions and resolve their problems with on-camera "group therapy".  Similar shows are popular throughout Europe.

Reeves Farmstead Historic District: The Reeves Farmstead Historic District is a nationally recognized historic district located north of Le Mars, Iowa, United States.  It was listed on the National Register of Historic Places in 2001.  At the time of its nomination the district consisted of 13 resources, including 11 contributing buildings, one non-contributing building, and one non-contributing object.  The contributing buildings include an American Four Square house, a barn, cob house and wash house, hen house, outhouse, machine shed, corn crib, two hog houses, and a garage.  The non-contributing building is a second garage built in the late 20th century, and the non-contributing object is an incomplete wind mill.  The buildings were all built in the late 19th- or early 20th century, but exact dates are uncertain.  The fully integrated farmstead from the early to mid 20th century features buildings that utilize simple architecture that was typical of many Iowa farms.

Rocky Mountain Arsenal: The Rocky Mountain Arsenal was a United States chemical weapons manufacturing center located in the Denver Metropolitan Area in Commerce City, Colorado.  The site was completed December 1942, operated by the United States Army throughout the later 20th century and was controversial among local residents until its closure in 1992.

National Eagle Repository: The National Eagle Repository is operated and managed under the Office of Law Enforcement of the United States Fish and Wildlife Service located at the Rocky Mountain Arsenal National Wildlife Refuge outside of Denver, Colorado.  It serves as central location for the receipt, storage, and distribution of bald and golden eagles that have been found dead.  Eagles and eagle parts are available only to Native Americans enrolled in federally recognized tribes for use in religious and cultural ceremonies.

Supporting paragraphs: Basin F Rocky Mountain Arsenal
Answer: United States Army