Atop an enormous mound of rubble under blistering sun in Iraqs second city Mosul, fire crews and police chip away at a grim but vital task. Some 10 months after dislodging ISIS, they are still extracting bodies from the ruins of the shattered Old City. "Over three days, 763 bodies have been pulled from the rubble and buried," Lieutenant Colonel Rabie Ibrahim tells Agence France Presse. Despite the overpowering stench, the men work relentlessly, braving unexploded munitions in an area devastated by the nine-month battle.  "The operations will continue until all the corpses are extracted" from the heart of the city, Ibrahim says. Civilians bodies that can be identified are handed to their families, while the remains of ISIS combatants are buried in a mass grave on the western outskirts of Mosul.  Some of the putrified corpses are sent to Nineveh provinces health services, Ibrahim adds. The workers, their faces covered with masks or scarves, move with great caution. The bodies of militants are sometimes still clad in suicide belts.  Grenades, homemade bombs and other crude contraptions left by ISIS fighters during their retreat to Syria pose a constant threat.  The improvised boobytraps are hidden under multiple layers and obstacles -- the rubble of collapsed homes, disemboweled furniture and uprooted trees, in some places subsiding into the waters of the Tigris that meander murkily below.  Where a maze of cobbled streets was once lined with homes and market stalls, there is now a formless mess populated by stray animals, insects and disease. The destruction is so great that some residents cannot pinpoint the remnants of their homes or even their street as they try to direct salvage workers to the remains of loved ones. The rubble makes it impossible to bring in heavy construction machinery, says General Hossam Khalil, who leads Nineveh provinces civil defense force.  His men therefore have to rely on smaller vehicles, but Mosul "only has a few," he says. There is a pressure to work as quickly as conditions will allow: residents are exhausted by three years of ISIS rule, nine months of brutal urban combat and now the slow pace of reconstruction.  "But its impossible, with this stench, this pollution and the epidemics they can cause," says Othmane Saad, an unemployed 40-year-old whose home in the old city is entirely destroyed. Another resident, 33-year-old Abu Adel, wants the authorities "to clear all the corpses as quickly as possible" and to "compensate residents so they can rebuild, then establish public services". But the task is titanic.  Since Mosul was retaken in July, "2,838 bodies, including 600 ISIS members, have been retrieved from the rubble," governor Naufel Sultane tells AFP.  Even after the corpses are taken away and buried, they leave harmful bacteria which the Tigris can carry far beyond the old city. The authorities insist drinking water stations are unaffected and that they pump water from the Tigris central depths, avoiding the banks and other shallows.  But gastroenterologist Ahmed Ibrahim advises caution.  "You must boil water before drinking it and dont use river water, either for bathing or washing," he tells AFP. Birds and fish "can carry typhus, bilharzia and gastroenteritis," he adds.