Numerous changes occurred in and around the Pio Pico House soon after the Adobe was built in 1852. Due to the proximity of the San Gabriel River, the structure suffered damage, requiring some amount of rebuilding several times. The natural tendency of the river to flood and change its banks was the basic cause for much of the early rebuilding. After 1900, various groups responsible for the upkeep and restoration of the site also made additional structural changes. Two previous archaeological excavations occurred here by the Archaeological Survey of Southern California [ASA] and Cypress College. ASA excavated within the adobe and located both historic and prehistoric materials.
SRSinc was retained by the Pio Pico Docent Committee to oversee volunteers and staff and look at exterior areas. Initial research revolved around exploring historic cartography starting with 1862 plat map, 1865 George Hansen survey, followed by an 1879 Ruxton survey, 1933 HABS floor plan of the first floor, and a 1944 Frank Gutierrez map. These were enlarged or reduced to the same scale, overlain and compared to each other and to 26 historic photographs, which provided the basis for visualizing past walls and porches, now missing. Geophysical investigations were then performed to pinpoint suspected buried foundations, and excavations were subsequently conducted in order to verify the geophysical results. This stepped program resulted in the verification of a suspected 1880s trash pit adjacent to the SE corner of the structure, the location of foundation remains extending off the NW corner, and documentation of stratigraphy within the present north porch showing successive construction eras. The investigations also included extensive research on historic events and a flood chronology for the area, clarifying the relationship between the Adobe and natural and cultural actions, which collectively had a strong effect on the Pico Casa.
comprised documenting historic ranch structures and equipment before demolition for development was to occur. An integral part of the project was HABS/HAER studies. The Historic American Buildings Survey (HABS) and the Historic American Engineering Record (HAER) have comprehensive documentation requirements specified by the Library of Congress, which SRSINC uses for recording significant buildings and involves measuring, photographing, and preparation of technical architectural drawings.
The structures/equipment photo-documented, and drawn using HABS/HAER Guidelines and technical quality, for this project included: Main House with porch, old Horse/ Hay Barn, Blacksmith Shop, Grain Storage Barn, Shed, Stock Barn, Chicken House, Tank House, Small House, Site of the Old Windmill, Second Shed, Pantry, Third Shed, Garage, Privy, and possible Outhouse Locations. A second phase consisted of evaluation of the construction history of the main house and the out buildings with a specialist in Southern California Vernacular Rural Architecture.
Surface artifacts included 45 significant historic items including: Horse Drawn Mower, Spring Tooth Harrow, Horse Drawn Sulky, 1920s Gas Pump, and a Horse Drawn Fresno. Technical drawings were also made of the historic equipment. The blacksmith shop and privy were then dismantled and moved to the Gilman Ranch County Park. All boards from the privy and blacksmith shop were numbered and the numbers keyed to copies of the HABS/HAER drawings; using these drawings, the structures were restored by Gilman Ranch Hands. All materials, records and documents, photographs and original HABS/ HAER drawings, were also donated to the Park. Still, today, these can be seen as a significant contribution to the breadth of the Historic Building Museum.