.net - long running sql procedure hangs website -

i have mvc 4 web application calls business layer calls data layer method executesp asynchronously. data layer method executesp calls long running stored procedure this:

public class maindatalayer {     private database database;  //enterprise library 5      private dbcommand dbc;     private list<spparams> spparams;      public maindatalayer()     {         _database = databasefactory.createdatabase("strconn");          //set multiple sp params 1 below          _spparams.add(new spparams() { paramname = "@pid", paramvalue = id });      }      public dataset executesp()     {          dbc = database.getstoredproccommand('long_running_sp');         dbc.commandtimeout = 300;          foreach (spparams p in spparams)         {             dbc.parameters.add(new sqlparameter(p.paramname, p.paramvalue));         }          dataset ds = _database.executedataset(dbc);          return ds; } }   //this class used in class above setting sp parameters public class spparams {     public string paramname { get; set; }     public object paramvalue { get; set; }  } 

the long running stored procedure has few inserts , few updates , final time out call below simulate long running process.

waitfor delay '0:02:00' 

the problem is when call stored procedure thru web application deployed on test server client pc a, hangs further calls same client or other user calling webpage until 2 minutes in stored procedure have elapsed. when run stored procedure directly sql management studio , run sql statement side side, stored procedure takes 2 minutes execute , other sql statement executes immediately. doesnt there on database side need change. problem code?

thanks