Agenda item

Restoration of ground floor shopfronts, internal alterations across ground and lower ground floor and the installation of comfort cooling within central lightwell at first floor level (within new plant enclosure) and ventilation ducts within ground floor lightwell. Use of lower ground floor of 44 Mortimer Street and rear ground floor of 44 Mortimer Street (Little Titchfield Street frontage), as flexible/alternative Retail or Gymnasium (Class A1 or D2) use, with access to proposed gymnasium or shop from new entrance (at rear of 44 Mortimer St) adjacent to 1a Little Titchfield Street. Use of ground and lower ground floors of 46-50 Mortimer Street as Retail (Class A1).

An additional representation was received from the occupier of Flat 1, Ames House, 44 Mortimer Street, London (23.12.2019)

A late representation was received from the occupier of Flat 4, 44 Mortimer Street (7.1.2019).

The presenting officer tabled the following changes to the draft decision letter:

9          (1) Where noise emitted from the proposed plant and machinery will not contain tones or will not be intermittent, the 'A' weighted sound pressure level from the plant and machinery (including non-emergency auxiliary plant and generators) hereby permitted, when operating at its noisiest, shall not at any time exceed a value of 5 dB below the minimum external background noise, at a point 1 metre outside any window of any residential and other noise sensitive property, unless and until a fixed maximum noise level is approved by the City Council. The background level should be expressed in terms of the lowest LA90, 15 mins during the proposed hours of operation. The plant-specific noise level should be expressed as LAeqTm, and shall be representative of the plant operating at its maximum.

            (2) Where noise emitted from the proposed plant and machinery will contain tones or will be intermittent, the 'A' weighted sound pressure level from the plant and machinery (including non-emergency auxiliary plant and generators) hereby permitted, when operating at its noisiest, shall not at any time exceed a value of 10 dB below the minimum external background noise, at a point 1 metre outside any window of any residential and other noise sensitive property, unless and until a fixed maximum noise level is approved by the City Council. The background level should be expressed in terms of  the lowest LA90, 15 mins during the proposed hours of operation. The plant-specific noise level should be expressed as LAeqTm, and shall be representative of the plant operating at its maximum.

            (3) Following installation of the plant and equipment, you may apply in writing to the City Council for a fixed maximum noise level to be approved. This is to be done by submitting a further noise report confirming previous details and subsequent measurement data of the installed plant, including a proposed fixed noise level for approval by the City Council. Your submission of a noise report must include:

(a) A schedule of all plant and equipment that formed part of this application;

(b) Locations of the plant and machinery and associated: ducting; attenuation and damping equipment;

(c) Manufacturer specifications of sound emissions in octave or third octave detail;

(d) The location of most affected noise sensitive receptor location and the most affected window of it;

(e) Distances between plant & equipment and receptor location/s and any mitigating features that may attenuate the sound level received at the most affected receptor location;

(f)  Measurements of existing LA90, 15 mins levels recorded one metre outside and in front of the window referred to in (d) above (or a suitable representative position), at times when background noise is at its lowest during hours when the plant and equipment will operate. This acoustic survey to be conducted in conformity to BS 7445 in respect of measurement methodology and procedures;

(g) The lowest existing L A90, 15 mins measurement recorded under (f) above;

(h) Measurement evidence and any calculations demonstrating that plant and equipment complies with the planning condition;

(i) The proposed maximum noise level to be emitted by the plant and equipment.

Reason:

To protect the privacy and environment of people in neighbouring properties. This is as set out in S29 and S32 of Westminster's City Plan (November 2016) and ENV 6 and ENV 13 of our Unitary Development Plan that we adopted in January 2007. (R21BC)

12        a) Before you use the plant within the central lightwell at first floor level you must implement the mitigation measures set out in RBA Acoustic’s Plant Noise Assessment report dated 2 August 2018 Revision 2, in particular you must fully enclose the condensers with acoustic louvres, including a lid. You must then maintain it in the form shown for as long as the machinery remains in place.

            b) You must not operate the plant/ machinery that we have allowed (other than to carry out the survey required by this condition) until you have then carried out and sent us a post-commissioning noise survey and we have approved the details of the survey in writing. The post-commissioning noise survey must demonstrate that the plant/ machinery complies with the noise criteria set out in condition 9 of this permission.

RESOLVED:

1.         That conditional permission be granted subject to the amendment to condition 9 and condition 12.

2.         That conditional listed building consent be granted.

3.         That the reasons for granting listed building consent as set out in Informative 1 of the draft decision letter be agreed.