Thicket Excavations

Thicket Excavations is a quarry located in the northwest Commonwealth in 2287.

Background
This quarry has a reputation across the Commonwealth for producing the finest mirelurk meat due to the waters giving it a better flavor.

Layout
A fenced in quarry area that has been flooded, it is found to have scatters of cut stone around it. There are stairways leading up the north side of the quarry and a sloped ramp that extends into the water. The top level on the east side includes an elevator as well as a camper in which Sully Mathis's terminal can be found which details his plans for restoring the quarry for use as a base. There are several campers spread out around the nearby area.

If the water is drained from the quarry during Pull the Plug, then Sully will later (when then Sole Survivor next returns) be found to have brought in his gang of raiders, and these hostile raiders will be found spread out throughout the quarry. Sully Mathis will now be found to be much more powerful - minimum level 30 - and like the raiders will henceforth be implacably hostile regardless of any prior help he was given. Three Mirelurk pens will also be found in the area.

Notable loot

 * Taboo Tattoos issue #2 - In the trailer directly southwest of the water pump - only after the water has been fully drained from the quarry.
 * Sully's journal - Holotape in the east trailer inside of a terminal.

Related quests

 * Pull the Plug - Sully Mathis will ask for help to repair the pipes of the water pump and empty the quarry of the irradiated water. After completing the quest and 24 hours have passed, Sully Mathis will be hostile, and be the leader of a raider gang which he initially commented about doing in his terminal entries. However if he is killed immediately after the end of the quest, that will be that.
 * Raider Troubles - Once Pull the Plug has been completed, troublesome raiders might take refuge at this location between two attacks on the Commonwealth settlers.

Appearances
Thicket Excavations only appears in Fallout 4.

Bugs

 * Upon arrival at Thicket Excavation there seems to be a foglike low-res concrete-floor, hovering above most of the real surfaces, and it persists under water. It is the high distance version of the model (aka LOD) you should only see when the object is very far away. This manifests in that both the Sole Survivor and Sully Mathis wade knee deep in concrete, Sully always hovers around the compressor/pump, before the Sole Survivor suddenly falls into the water or the access-way leading down into the excavation. The impact of this bug can be negated by restarting the game.
 * If you swim under water to enter the excavation site before draining it, you will fall down to the floor and be able to walk and shoot your gun under water. In some cases Dogmeat may also teleport down to you and swim in place as he tries to follow you.
 * If you swim around enough before draining the quarry it is possible to cause the quarry to instantaneously empty of water and update the world/quest state such that the previously mentioned enemies (raiders, mirelurks) appear.
 * Occasionally, the caged Mirelurks will spawn outside of their cages. Caged Mirelurks only turn hostile when attacked, or when the Sole Survivor (or a companion) enters their cage, so the Mirelurks will roam around without turning hostile. This results in a sort of peaceful Mirelurk. Upon closer examination, Mirelurks are kinda cute... This is a personal entry, and it just happened to me, so I don't even know if it works on other platforms.