Attachment 1_Water tower inpsection report.pdf

Water Tower Inspection

Church Street

Sun Prairie WI

Prepared by Vaughan Weeks P.E. 4/30/2021

Contents Background

Repair Recommendations

Maintenance Recommendations

Description

Observations

Discussion

Exterior

Interior

Background

On 3/23/2021 Vaughan Weeks P.E. (hereafter: “Author”) inspected the historic water tower located on Church Street in Sun Prairie Wisconsin. The purpose was to produce a general evaluation of the tower’s current condition and to make recommendations regarding both repairs and steps that might be taken to maintain the structure long term.

Repair Recommendations Reinforce crosspiece ends

Repair water damaged exterior stonework

Seal steel deck and direct the drainage away from the building

Repair the windowsills

Disconnect the tank from the city water supply

Maintenance Recommendations Tuck Point

Provide interior ventilation

Description The Sun Prairie Water Tower is 60' high, rising from a two-foot rusticated stone foundation which is now almost entirely below the level of the surrounding plaza and street. The tower is topped with a steel tank which adds 30' bringing it to an overall height of 92'. Its outside diameter at the foundation is 25'.

The tower itself has an inside diameter of 20'. The first 11' of rise (approximately) is cylindrical. Above this base, marked by a setback of about 8", the circumference of the tower diminishes slightly as it rises.

The stonework is limestone with a pale yellow color and an even texture. There are five windows in the tower. The highest of these is near the top and faces north. Opposite this window, in the south side of the tower at the same level, is a door which gives access to a steel platform and ladder leading to the tank on the top of the tower. The windows are rectangular, approximately two feet wide and five feet high. The stone lintels and sills are of stone with some patching mortar applied to the sills. (Details rely on Historical Registration Documents.)

Observations

Exterior observations were made from ground level and from a lift capable of reaching the top of the tower. Interior observations were made from ground level and both temporary and installed ladders.

Stonework in good condition

Over most of the surface, the stonework was seen to be in good condition.

The interior stonework is sound but is subjected to running water promoting algae growth and corrosion of lateral steel members. Windowsill openings and areas where the decking is directing flow appear to be the sources of the flows and the resultant green algae staining.

There are also cut-out pockets on the interior wall that originally served as bearing points for wood decking or stairs. Some of these cutouts have been filled in, some are empty, and some still have the stubs of wood beams in them.

Discussion The tower is currently structurally sound. The exterior stonework is good but needs tuck pointing, primarily where windows or the deck have directed water flow over the outside of the building.

Gaps in the elevated steel deck should be sealed and drains added or re-established to prevent the run off from the deck from adhering to the side of the tower.

Exterior Mortar in need of tuck-pointing

Window sills need to be replaced/sealed

Water flow down outside of building has eroded some mortar. This flow is largely being directed by openings in the deck above it

Interior The interior wall is awash with flowing water directed from the outside in. Since the installation of new windows, the ventilation from normal air leakage has been greatly reduced providing a high humidity interior environment that appears to be supporting algae. This interior water has also corroded away the mounting points of the steel crosspieces.

The interior steel crosspieces are placed to provide lateral support to the main pipe at the hub connections. The top surface of these cross pieces is pitted and eroded by water. The ends are corroding away particularly where they are in one of the water flow paths.

The crosspieces can be reattached to the walls using bolt-up angles. Square head bolts and nuts would be chronologically correct. Galvanized steel brackets painted to match the surviving steel is recommended

Dimensins should be field checked before fabricating these parts.

Natural interior ventilation can be restored by placing a vent in the bottom of the ground level door and opening one of the upper windows enough to allowing naturally heated air to leave.

Finally, there is a large hand wheel valve at the base of the main pipe. This valve is in the closed position but it may be the only thing isolating the tower from the current water supply. Unless the tower is disconnected from the water system elsewhere, opening this valve will probably try to fill the tank and immediately supply water to the open small diameter drain valve above it. It is recommended that the security of this valve be reviewed by the utility department.