The 2013 excavations, undertaken by Zurich University’s Institute of Archaeology in the town of Spina, aimed to check the plan of the rectangular building dating to period IX (c. mid 4th century B.C.), and excavate the channels in the western and northern parts of the site.

The northern channel, the widest (2.2 m to the east – 2.3 m to the west) and perhaps navigable by small boats, certainly continued towards the west and to the east (just beyond the trench edge) must have met the large, navigable north-south channel. The excavation of the first fill in the two channels (US 117) led to the discovery of a large number of perfectly aligned timber posts (there are about 150; 85 in the west channel and 60 in the north channel), the upper parts eroded away. Both banks were contained and protected by timber planks slotted horizontally between two parallel rows of close-set posts. In fact, pieces of the planks were preserved along the banks of the channels. A single row of posts divided the north channel almost in half longitudinally (it was at 1.2 m from the southern bank). The function of this row of posts is unknown at the moment.

The western channel was 95-100 cm wide and -3.20 m a.s.l. and met the north channel at a right angle, but did not continue beyond it, as shown by the uninterrupted timber structure on the north bank of the north channel.

Subsequently, at the time of the salt pan (period VII, early Hellenistic), the channels were largely filled and this fill (US 117) must have covered the posts that were by then no longer visible and out of use. At this stage, the channels must have appeared as shallow depressions. It is possible that these depressions permitted the introduction of the salt water into the zone necessary for boiling the salt via the process of briquetage.

There were new findings in the period IX rectangular building (c. mid 4th century B.C.), characterised by a large number of small terracotta slabs found along its perimeter. New burnt timber beams and a number of postholes were uncovered at the southern edge of the trench. The beams were perfectly aligned with the rest of the building’s perimeter and therefore certainly formed part of the south wall itself. The plan of this building is now complete, it measured 7 m east to west and 6 m north to south. The perimeter beams, housed in a narrow channel, were followed, as in the internal walls, by several reinforced postholes, a particular technique for this structure and not seen in the earlier period XI building. This building, with a slightly off-centre oven (or hearth?) had an almost square plan and was small (42 m2). It had no internal supporting posts and the walls were characterised by abundant baked clay fragments and timber base housing beams, reinforced and protected from damp by characteristic small terracotta slabs. Round postholes were present at regular intervals between the beams.