SQL Server administration script

We are in SQLServer 2012 environment. Need some help to create a procedure that will kill blocking SPID for a particular database ( say the database name is mydb ) by a specific login ( say domainname\username ) if this login blocks mydb process for more than 5 min. We found that a particular login which is performing read on the database is blocking the load process for the same database. We want to execute the proc every 15 min to kill any blocking SPID.