Error:
Memory gates checking failed because the free memory (517894144 bytes) is less than 5% of total memory. As a result, the service will not be available for incoming requests. To resolve this, either reduce the load on the machine or adjust the value of minFreeMemoryPercentageToActivateService on the serviceHostingEnvironment config element.

Solution:

Add this into your web.config

<system .servicemodel="">
    <servicehostingenvironment minfreememorypercentagetoactivateservice="0">
</servicehostingenvironment></system> 



orginal post : http://stackoverflow.com/a/17449862/1465743