Tarlton Properties, Inc. (TPI) a Menlo Park-based commercial property development and management firm, recently added two buildings to its O'Brien Drive portfolio. With the purchase of 1001 O'Brien and 1320 Willow Rd. from Balco Properties for $18 million, TPI added approximately 77,000 square feet consisting of 50,000 square feet of warehouse space at 1320 Willow and 20,000 square feet of light industrial space at 1001 O'Brien.