Expand IQueryable to use custom linq extension

Question

For using MVC JqGrid following this tutorial I'm adding some Linq extensions, basically these:

public static IQueryable<T> OrderBy<T>(this IQueryable<T> query, string sortColumn, string direction)
{
    //...
    return query.Provider.CreateQuery<T>(result);
}

public static IQueryable<T> Where<T>(this IQueryable<T> query,
            string column, object value, WhereOperation operation)
{

    //....
    return query.Provider.CreateQuery<T>(result);

}

Thing is that I don't really like the idea of having these extension methods accessible for any query as I consider them to be very related to the JqGrid so I was trying to create a IJqQueryable that extends the IQueryable and then these two would be something like:

public static IJqQueryable<T> OrderBy<T>(this IJqQueryable<T> query, string sortColumn, string direction)
{
    //Same code as before

    var normalQuery = query.Provider.CreateQuery<T>(result);

    return normalQuery as IJqQueryable<T>;
}

public static IJqQueryable<T> Where<T>(this IJqQueryable<T> query,
    string column, object value, WhereOperation operation)
{
    //Same code as before

    var normalQuery =  query.Provider.CreateQuery<T>(result);

    return normalQuery as IJqQueryable<T>;

}

For that I only created this interface:

public interface IJqQueryable<T> : IQueryable<T>
{
}

And now my problem is that I would need the equivalent to AsQueryable() because my controller action method looks like (before the change to use IJqQueryable)

public JsonResult ComplaintTypes(GridSettings grid)
{
    var complaintTypes = _queryComplaintTypes.GetAll();

    Func<ComplaintType, Object> lambda = (complaintType => (new {
                                                complaintType.ComplaintDescription,
                                                complaintType.ComplaintTypeId
                                            }));

    var result = _jqGridFactory.Get(grid, complaintTypes.AsQueryable(), lambda);

    return Json(result, JsonRequestBehavior.AllowGet);
}

and apparently I can't use as IJqQueryable or cast it to (IJqQueryable) complaintTypes.

Hope I made it reasonably clear, will appreciate any idea

Thanks