Owners of Oxnard’s Serenade at RiverPark apartment complex have just bought a neighboring apartment community. L.A. real estate investment firm JRK Property Holdings said it has bought the Rancho Solana apartments at 2444 Alvarado St. on the peripheral of RiverPark for $30.7 million, or nearly $183,000 per unit. The 168-unit, garden style complex of 15 buildings is about a mile from the Serenade apartments, which JRK bought a year ago in May. RiverPark is a master-planned community with residences, schools and parks near the Collection retail shopping center off the 101 Freeway. Rancho Solana, built in 1973, includes one-, two- and three-bedroom units, a pool, spa, barbeque area, playground and covered parking and was 99 percent leased at the time of the sale, according to JRK. James Bloomingdale, senior vice president and head of acquisitions for JRK, said buying a second, nearby complex will enable it to benefit from economies of scale and minimize operating costs. The company also plans to modernize the units and common areas. The community was last renovated in 2003, according to CoStar Group Inc. Gregory Harris, Kevin Green and Joseph Grabiec of Calabasas real estate brokerage Marcus & Millichap Inc.’s Institutional Property Advisors division brokered the deal on behalf of JRK and the seller. According to CoStar, commercial real estate services company Tom Redfern & Associates in Carmel paid about $29.6 million for the complex in 2007.