Grab some weapons from the crash site and deploy the ranged sentinels as well. If you activate the declassify mission for this section, serapedes and corpsers will join the attack waves. Deploy the auto-turrets in the chokepoints of your position so you can easily reload them when necessary. When dealing with Corpsers, you have to shoot their faces when they expose it.
For the second wave, you have to fend off heavy enemy attacks. Using grenades and the gnasher shotgun might be a good alternative in dealing with these heavy attackers up close. Just aim for the head to take them out.