Monica Arellano is vice chairwoman of the Muwekma Ohlone Tribe of the San Francisco Bay Area and the tribe's Historic Preservation officer. She is designated by the tribe as the member who responds when excavation work uncovers human remains determined to be of Native American origin, and acts as representative for the most likely descendant of the deceased.

Representatives of the Muwekma Ohlone tribe say that the site almost certainly contains Native American burials. They are confident there will be more remains found there if and when the developer starts digging.

It turns out that those burials are just a small part of what may be an ancient Native American village long buried beneath the earth in the area where Facebook's planned new neighborhood and office campus would be – a project that would include 1.75 million square feet of office space, 1,735 housing units, retail space including a grocery store, and a hotel.

Where those remains were found, at the former Pacific Biosciences campus at 1005 Hamilton Ave., is exactly where Facebook is proposing to build its Willow Village project.

In November 2012, The Almanac published a short news item reporting that construction crews working in Menlo Park had unearthed two human skulls while ripping up concrete. The skulls were later determined to be Native American remains.

More than 425 shellmounds, or Ohlone burial sites and shell deposit structures, used to ring the San Francisco Bay. This section of a 1909 map highlights Peninsula shellmound sites, as published in a report by N.C. Nelson in the Berkeley University Press. (Image courtesy of University of California Publications Department of Anthropology)

More than 425 shellmounds, or Ohlone burial sites and shell deposit structures, used to ring the San Francisco Bay. This 1909 map shows some of the areas they were found, as published in a report by N.C. Nelson in the Berkeley University Press. (Image courtesy University of California Publications Department of Anthropology)

Three sites, the Hiller mound, the Tarlton site and the University Village site, demonstrate the dense habitation of Native Americans in the area at different times along the southern bayshore of what's now San Mateo County, according to a 1988 report from archaeologists Robert Cartier and Judy Carrico. (Image courtesy of Society for California Archaeology)

In particular, he noted, a known archaeology site known as the Hiller mound appears to be exactly within the footprint of Facebook's Willow Village project. The mound is one of more than 425 shellmounds that once surrounded the San Francisco Bay, as recorded by University of California archaeologist N.C. Nelson in a 1909 report .

Michael Wilcox, archaeology professor at Stanford and unpaid consultant for the tribe, confirmed Arellano's statement, telling The Almanac, "There will be burials there. There's no doubt about it."

In a written statement to The Almanac, Arellano said: "There is a high likelihood that the project will result in the disturbance of burials and the destruction of cultural resources. We hope that Facebook will consult and work closely with the tribe as this project unfolds."

In a statement to The Almanac, Signature President Michael Ghielmetti said that "the project team has had preliminary outreach with the tribes. The Hiller mound is being studied as part of the Environmental Impact Report. As studies and site surveys progress, more outreach and dialogue with the tribes in regard to the respectful treatment of the site will be initiated, in accordance with state law."

The head of the firm Facebook is working with on the project, Signature Development Group, told The Almanac that the firm is aware of the Hiller mound and plans to study it in the environmental impact review process.

According to a recent KQED story about shellmounds, these mounds are man-made creations of earth and organic matter built up by the indigenous people of the San Francisco Bay Area over thousands of years. They were places for ceremonies, burials, trading and even signaling across the waters of the bay, or to communicate with other tribes, and were where food waste – specifically, lots of shellfish husks – was discarded.

A public meeting is scheduled Monday, Dec. 16, starting at 5:15 p.m. in the City Council chambers at 701 Laurel St., during which the City Council will be presented with an overview about the comments already made and may make suggestions on the scope of the environmental impact analysis. No additional comments about the scope of the analysis will be accepted, according to city staff.

Menlo Park has entered into a $1.11 million contract with consultants from ICF Jones & Stokes, Inc. to prepare an environmental impact report on the proposed Willow Village project . The city has collected comments in response to a notice of preparation, which asks people to weigh in on which areas they think should be analyzed during an environmental impact analysis.

In 2014, a Bobcat operator found a human bone in the mud while doing excavation work. It turned out to be the grave of a young man whose body was folded into the fetal position and found wrapped in woven matting and buried wooden tools. Carbon-14 dating would later determine that the man had lived about 7,500 years ago, and as such, is one of the oldest humans ever found in California. The remains were surprisingly well-preserved in dense, marshy soil, as described in the anthropology publication " Anthro Now ."

Still, despite its shortcomings, the existing system has yielded impressive discoveries in recent years, like that of the Transbay Man, a set of human remains found during excavation at the new $4.5 billion Transbay Transit Center in San Francisco.

Under California law, whenever human remains are found during excavation work, the work must stop and the coroner's office must be contacted to ensure that the body found is not from contemporary times. If the coroner finds that the remains are of a Native American, then he or she must contact the Native American Heritage Commission. Then, the "most likely descendant" of the person buried is contacted and can provide a recommendation about what to do with the remains. All of this, Wilcox said, can be expensive for the developer, who has to bear the costs of the additional research, and of rented excavation equipment not being put to use.

With all of the construction work happening on the Peninsula, there is great potential for archaeological discoveries to be made, but, Wilcox noted, there are often incentives for inspectors to not look too closely, or to look the other way and not halt development work if they come across potential artifacts or remains.

In an ethnohistory of the group, Milliken reports that the last of the descendants from the Puichon tribe, or that of the Lamchin tribe, which occupied the San Francisquito Creek farther upstream, was likely a member of the Evencio family, and the family's whereabouts were last known around the 1930s. There were no other West Bay Ohlone tribal groups that are believed to have survived into the late 20th century, according to Milliken.

Archaeologist Randall Milliken in a 2007 report states that the Puichon people from the village were sent to Mission Dolores in San Francisco between 1781 and 1794 and to Mission Santa Clara in Santa Clara between 1781 and 1805. The village of Ssiputca is mentioned six times in the "Libro de Bautismos" or book of baptisms, at the San Francisco mission, he adds.

Research suggests "that the contact-period village of Ssiputca may be one of two destroyed mounds (possibly the Hiller Mound) near the bayshore in East Palo Alto," she writes. In addition, Cartier's report suggests that the mouth of the creek may have had a different alignment in the past and finds evidence indicating the "probable presence" of the creek near the Hiller mound at one time.

Beyond the fact that the Hiller mound area was heavily inhabited by Native Americans, she adds, it may even be site of Ssiputca, a village assumed to be located at the mouth of the San Francisquito Creek that existed at the time European explorers first made contact with indigenous people of the area in the 1700s.

Bocek writes, "Incomplete and contradictory records notwithstanding, there is ample evidence to suggest that at contact (with Europeans), two or three tribelets may have shared the San Francisquito area in the southern Peninsula."

A 1992 report in the same publication by Stanford archaeologist Barbara Bocek explains that the Hiller mound holds information about the Puichon tribal group that resided along the bayshore and along the lower stretches of San Francisquito Creek. The site comprises at least 8,000 square meters – or about 86,000 square feet – though materials can be found throughout an area twice that size. Radiocarbon testing dated the age of artifacts to be between 687 and 1,687 years old.

The Hiller site was excavated significantly during the 1950s, with up to 30 10-by-10-meter test sites exploring up to 4 feet underground, and appears to have been inhabited more recently than the University Village site.

The report compares findings from the Hiller site with those of two nearby archaeological sites, the Tarlton site – located about a half-mile east near the rail line – and the University Village site in East Palo Alto.

The site lies amid the parking lots and single-story office buildings of the former Prologis campus, and is roughly between where Facebook plans to build a visitor parking garage and where it's proposing to locate the northernmost of its office buildings, which would rise up to 85 feet tall.

According to a 1988 report by archaeologists Robert Cartier and Judy Carrico published with the Society for California Archaeology, the Hiller mound is located just inland of the Dumbarton rail line, and a short distance southeast of Willow Road.

Facebook wants to build on what may be a former indigenous village