arcgis desktop - Out of memory when running ModelBuilder?

I'm currently using ArcGIS 10.3.1 on a 64 bit windows 7 machine.

When I run the following model, every iteration adds about 20 consistent megabytes into the ArcMap sessions memory until it eventually runs out.

I've tried adding a 'delete' function for in_memory. The output shows this works, but the 20 megabytes still keeps adding up.

It's the same thing that happens if you do several processes in ArcMap and eventually the memory gets used up, even if you're not storing extra datasets in the project.

Any ideas on how to eliminate this problem so the memory won't run out?

HERE'S THE OUTPUT REPORTING RESULTS:

Executing (Iterate Field Values): IterateFieldValues C:\Projects\Yakima_Basin_Study_0410\KtoKPipeline_KachessInactive\Kachess_Capacity_Table_Contours\Kachess_Capacity_1015\Kachess_Capacity_1015.gdb\IterationTable0316 Iteration Double true false 0 Start Time: Wed Mar 30 06:24:39 2016 Succeeded at Wed Mar 30 06:24:39 2016 (Elapsed Time: 0.19 seconds) Executing (Surface Volume): SurfaceVolume C:\Projects\Yakima_Basin_Study_0410\KtoKPipeline_KachessInactive\Kachess_Capacity_Table_Contours\Kachess_Capacity_1015\TIN_KACDam_BORDatum_0316 C:\Projects\Yakima_Basin_Study_0410\KtoKPipeline_KachessInactive\Kachess_Capacity_Table_Contours\Kachess_Capacity_1015\Kachess_Capacity_Output_Files\KACDam.txt BELOW 2133.01 1 0 Start Time: Wed Mar 30 06:24:43 2016 Completed Surface Volume: 2D Area=117053561.15555 3D Area=132153865.43817 Volume=19787611237.973 Succeeded at Wed Mar 30 06:25:02 2016 (Elapsed Time: 19.57 seconds) Executing (Delete): Delete in_memory Workspace Start Time: Wed Mar 30 06:25:12 2016 Succeeded at Wed Mar 30 06:25:12 2016 (Elapsed Time: 0.01 seconds) Executing (Iterate Field Values): IterateFieldValues C:\Projects\Yakima_Basin_Study_0410\KtoKPipeline_KachessInactive\Kachess_Capacity_Table_Contours\Kachess_Capacity_1015\Kachess_Capacity_1015.gdb\IterationTable0316 Iteration Double true false 0 Start Time: Wed Mar 30 06:25:12 2016 Succeeded at Wed Mar 30 06:25:12 2016 (Elapsed Time: 0.02 seconds) Executing (Surface Volume): SurfaceVolume C:\Projects\Yakima_Basin_Study_0410\KtoKPipeline_KachessInactive\Kachess_Capacity_Table_Contours\Kachess_Capacity_1015\TIN_KACDam_BORDatum_0316 C:\Projects\Yakima_Basin_Study_0410\KtoKPipeline_KachessInactive\Kachess_Capacity_Table_Contours\Kachess_Capacity_1015\Kachess_Capacity_Output_Files\KACDam.txt BELOW 2133.02 1 0 Start Time: Wed Mar 30 06:25:14 2016 Completed Surface Volume: 2D Area=117057436.47809 3D Area=132158168.43332 Volume=19788781792.957 Succeeded at Wed Mar 30 06:25:27 2016 (Elapsed Time: 12.63 seconds) Executing (Delete): Delete in_memory Workspace Start Time: Wed Mar 30 06:25:37 2016 Succeeded at Wed Mar 30 06:25:37 2016 (Elapsed Time: 0.01 seconds) Executing (Iterate Field Values): IterateFieldValues C:\Projects\Yakima_Basin_Study_0410\KtoKPipeline_KachessInactive\Kachess_Capacity_Table_Contours\Kachess_Capacity_1015\Kachess_Capacity_1015.gdb\IterationTable0316 Iteration Double true false 0 Start Time: Wed Mar 30 06:25:37 2016 Succeeded at Wed Mar 30 06:25:37 2016 (Elapsed Time: 0.02 seconds)