A collection tank for a mobile vacuum excavator, the collection tank comprising: a generally cylindrical body having a tank centerline; a front with a closed end; and a rear with an open end having a sealing flange that defines a first plane perpendicular to the tank centerline; a door (126, 226, 326, 426, 526, 626) pivotally connected to the generally cylindrical body and having a periphery that abuts the sealing flange of the open end when the door (126, 226, 326, 426, 526, 626) is closed over the open end; a first linkage arm (104, 204, 304, 404, 504, 604) having an end pivotally connected to the body; a second linkage arm (102, 202, 302, 402, 502, 602) having a first end pivotally connected to the door (126, 226, 326, 426, 526, 626) and a second end, wherein when the door (126, 226, 326, 426, 526, 626) is closed over the open end, the first end of the second linkage arm (102, 202, 302, 402, 502, 602) is rearward of the first plane and the second end of the second linkage arm (102, 202, 302, 402, 502, 602) is forward of the first plane; and an actuator (160, 260, 360, 460, 560, 660) having a first end that is pivotally connected to one of the first linkage arm (104, 204, 304, 404, 504, 604) or the second linkage arm (102, 202, 302, 402, 502, 602) at a first pivot point (168A, 261, 361, 466, 168) lying in a third plane that is perpendicular to the tank centerline; and a second end having a second pivot point (169A, 113, 311, 466, 169, 611) located between the first plane and the third plane; wherein the first pivot point (168A, 261, 361, 466, 168) and the second pivot point (169A, 113, 311, 466, 169, 611) lie in a plane that is parallel to or generally parallel to the tank centerline when the door (126, 226, 326, 426, 526, 626) is closed over the open end. a generally cylindrical body having a tank centerline; a front with a closed end; and a rear with an open end having a sealing flange that defines a first plane perpendicular to the tank centerline; a tank centerline; a front with a closed end; and a rear with an open end having a sealing flange that defines a first plane perpendicular to the tank centerline; a door (126, 226, 326, 426, 526, 626) pivotally connected to the generally cylindrical body and having a periphery that abuts the sealing flange of the open end when the door (126, 226, 326, 426, 526, 626) is closed over the open end; a first linkage arm (104, 204, 304, 404, 504, 604) having an end pivotally connected to the body; a second linkage arm (102, 202, 302, 402, 502, 602) having a first end pivotally connected to the door (126, 226, 326, 426, 526, 626) and a second end, wherein when the door (126, 226, 326, 426, 526, 626) is closed over the open end, the first end of the second linkage arm (102, 202, 302, 402, 502, 602) is rearward of the first plane and the second end of the second linkage arm (102, 202, 302, 402, 502, 602) is forward of the first plane; and an actuator (160, 260, 360, 460, 560, 660) having a first end that is pivotally connected to one of the first linkage arm (104, 204, 304, 404, 504, 604) or the second linkage arm (102, 202, 302, 402, 502, 602) at a first pivot point (168A, 261, 361, 466, 168) lying in a third plane that is perpendicular to the tank centerline; and a second end having a second pivot point (169A, 113, 311, 466, 169, 611) located between the first plane and the third plane; wherein the first pivot point (168A, 261, 361, 466, 168) and the second pivot point (169A, 113, 311, 466, 169, 611) lie in a plane that is parallel to or generally parallel to the tank centerline when the door (126, 226, 326, 426, 526, 626) is closed over the open end. a first end that is pivotally connected to one of the first linkage arm (104, 204, 304, 404, 504, 604) or the second linkage arm (102, 202, 302, 402, 502, 602) at a first pivot point (168A, 261, 361, 466, 168) lying in a third plane that is perpendicular to the tank centerline; and a second end having a second pivot point (169A, 113, 311, 466, 169, 611) located between the first plane and the third plane; wherein the first pivot point (168A, 261, 361, 466, 168) and the second pivot point (169A, 113, 311, 466, 169, 611) lie in a plane that is parallel to or generally parallel to the tank centerline when the door (126, 226, 326, 426, 526, 626) is closed over the open end.