John A. Boynton
Judith G. Boynton
42 St. Leonard’s Terrace
London SW3 4 QH
22 December 2015
Mr. Graham Stallwood
Executive Director
Planning and Borough Development
Royal Borough of Kensington and Chelsea
Town Hall
Hornton Street
London W8 7NX
Dear Mr. Stallwood:
Reference PP/15/07804
Construction of a Subterranean Extension (Basement), Additional Vault to Front of Property and
Skylights to Rear at 7 Durham Place, London SW3 4ET
OBJECTION
The above referenced Planning Application (PA) contains insufficient and/or incomplete information
in many areas and should be refused on that basis. In addition, we object to the above referenced
Planning Application (PA) because it is contrary to several Planning Policies regarding Basements, the
Protection of Trees, the Preservation of Conservation Areas, and Health and Safety, among others.
The proposed development would constitute a double basement and it would extend into more
than 50% of the rear garden, both of which would be contrary to RBKC Planning Policy. It would also
destroy and/or damage trees including four mature, evergreen trees in the rear garden that are
protected by virtue of being in the Royal Hospital Conservation Area. These four trees provide
privacy and residential amenity for many neighbours and natural habitat for birds and bats (which
are a protected species). The proposed development also would risk the health of a London Plane
Tree in the front of the property that is covered by a Tree Protection Order (TPO).
The cumulative effect of this proposed development and the large Rear Extension expansion
currently being proposed by the owner of 7 Durham Place (PP/15/07551) would be to significantly
reduce the greenspace and denigrate the beauty and character of the Conservation Area. The
proposed developments would also increase the sense of enclosure, decrease the privacy, and
denigrate residential amenity for neighbours. The proposed basement development would also risk
destabilizing the structure of this beautiful but fragile 1790 terrace house.
Further, the cumulative effect of the two proposed developments at 7 Durham Place together with
the approved Basement Development at 5-6 Durham Place (PP/15/04516) would significantly
increase the risk of structural damage to the entire historic terrace (1-7 Durham Place), 8-10 Durham
Place, and potentially 42, 43, and 44 St. Leonard’s Terrace. Because these basements would be
constructed across three adjacent properties (5, 6 and 7 Durham Place) to a depth of 8-9 metres,
through the water table, they would also increase the risk of flooding for all of the affected
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neighbours. The combined basement excavations at 5-6 and 7 Durham Place would create
unacceptable traffic issues and risks for the neighbourhood.
Finally, there are several aspects regarding noise, nuisance, and ventilation that would denigrate
residential amenity during construction and on an ongoing basis. Some of these aspects would
constitute health or safety risks to neighbours.
All of these objections are described in more detail below.
THE PROPOSED DEVELOPMENT IS A DOUBLE BASEMENT, CONTRARY TO PLANNING POLICY
The owner of 7 Durham Place is proposing to deepen by about 1-1.5 metres and extend his existing
“lower ground floor” by approximately 7 additional metres (as measured from the existing rear
extension façade) into his rear garden. The proposed extension of the “lower ground floor” would
be entirely subterranean (as confirmed in the Saville Planning Report and additional drawings
included with the PA). This subterranean extension constitutes a first basement under Planning
Policy. The owner also proposes to construct a second basement into the rear garden under the
new subterranean first basement, which is contrary to Planning Policy.
THE PROPOSED DEVELOPMENT EXTENDS INTO MORE THAN 50% OF THE REAR GARDEN,
CONTRARY TO PLANNING POLICY
RBKC Planning Policy restricts the construction of basements into no more than 50% of the rear
garden to preserve and enhance the green spaces in the Borough and to provide an adequate area
for water runoff and absorption. This PA states that the proposed double basement would extend
48% into the rear garden. There is insufficient information in the PA to confirm how the 48% figure
was calculated to prove its accuracy. However, it seems likely that the calculation assumes that the
garden extends from the current rear extension façade to the rear wall at the end of the property.
If this is the case, this 48% calculation is not correct as it does not take into account that 7 Durham
Place currently has a permanent 37 square metre building at the rear of its property, which the
planning document states was built circa 1951. This building is approximately 7.6 metres wide (the
full width of the garden) and approximately 4.9 metres deep. When the area of this building is
properly excluded from the garden dimension calculation, the proposed double basement would
extend into significantly greater than 50% into the garden, contrary to Planning Policy.
THE PROPOSED DEVELOPMENT DOES NOT INCLUDE A MINIMUM OF ONE METRE OF SOIL ABOVE
THE PORTION OF THE BASEMENTS BENEATH THE GARDEN, CONTRARY TO PLANNING POLICY
As proposed, there would not be a metre of soil above the double basement that would extend into
the garden. While the PA contains insufficient information about this important point, it appears
that there would be a concrete slab, metal trench sheeting, and garden surface hardscape above the
double basement. This situation would prevent the planting of trees, bushes, etc. in that portion of
the rear garden, since there would be insufficient soil for such plantings. Also, the absence of one
metre of soil would prevent rainfall absorption and increase the risk of surface flooding in an already
high risk area. It would also increase the risk of rising damp problems for nearby properties. For
these reasons, this proposal is contrary to RBKC Policy and should be refused.
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THE PROPOSED DEVELOPMENT WOULD DESTROY OR DAMAGE TREES THAT ARE PROTECTED BY
VIRTUE OF BEING IN A CONSERVATION AREA OR UNDER A TPO, CONTRARY TO PLANNING POLICY
At the front of 7 Durham Place is a 25 metre high mature London Plane tree. This tree is protected
by a specific TPO. Its trunk is approximately 7 metres from the front façade of the house. There is
no indication in the arborist report associated with this PA that any testing has been done to
determine whether any major roots of this tree would be damaged or severed by the construction of
the new vault and a seven to eight metre basement excavation under the main portion of the house.
This root testing should be completed before this PA is considered.
There are four 8 metre tall evergreen trees in the rear garden of 7 Durham Place which the arborist’s
report lists as Chinese Privet trees. These trees are protected by virtue of being in a Conservation
Area and should not be taken down or damaged in any way. The arborist’s report filed with the PA
for the proposed rear extension expansion (PP/15/07551) states definitively that there would be no
adverse impact on these trees. However, the above referenced basement PA tells a different story.
It states in various places that two trees (T1 and T4 which are closest to the house) would be felled
to accommodate the double basement. Other PA documents state that perhaps all four Chinese
Privet trees would be felled.
The arborist’s report and various other planning documents justify this action by stating that these
trees have little value. In fact, they are extremely important in providing privacy and residential
amenity to neighbours on St. Leonard’s Terrace, Durham Place and Tedworth Square and beauty and
character to our Conservation Area on a year round basis. They also provide important habitat for
birds and bats (a protected species) which are regularly seen in the back gardens of these homes.
The arborist report seems to imply that the felling of two Chinese Privet trees would have no
adverse impact on the other two Chinese Privet trees, since he does not mention any risks
associated with the remaining two trees. If the proposed felling of two Chinese Privet trees
occurred, it would be highly likely that the remaining two Chinese Privet trees would be damaged
and/or die because they are planted very close to the trees that would be removed.
For example, we measured the distance (trunk to trunk) between T3 and T4 in the rear garden that
are adjacent to the shared party garden wall between 7 Durham Place and 42, 43, and 44 St.
Leonard’s Terrace. The distance is slightly less than 2 metres. The arborist’s report incorrectly
places these trees at a distance of 3.35 metres from each other. This is a material error as the two
trees’ root protection areas are very likely to be intermingled given their stated root protection
radius of 1.7 metres each. This intermingling is likely to be very great since the arborist states that
the trees’ roots are impeded from growing under the party wall into the three St. Leonard’s Terrace
gardens.
The arborist’s report associated with this PA also makes no mention of any soil or root testing to
determine whether any significant roots of the four Chinese Privet trees in the rear garden of 7
Durham Place exist in the area where the double basement would be excavated. Therefore, a
complete root analysis for the four trees in the rear garden of 7 Durham Place should be conducted
before any PA is considered.
Finally, the PA suggests that the owners would replace any trees that are felled with other plantings.
Any new plantings would be too small and immature to replace the privacy value or residential
amenity of the existing trees in any reasonable time frame. In addition, there is significant doubt
about the future garden and landscaping design, scope, etc. given the lack of one metre of soil above
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the proposed basements as described above. This is particularly concerning given the existence of
the 37 square metre building in the rear of the property, which prevents any trees, bushes, or other
greenery from being planted in that area.
THE PROPOSED DEVELOPMENT WOULD INCREASE THE RISK OF STRUCTURAL INSTABILITY AND
FLOODING TO A HISTORIC CHELSEA TERRACE AND OTHER NEARBY PROPERTIES
The 1-7 Durham Place buildings date from 1790 and form a beautiful, historic, but fragile Chelsea
terrace. Based on conversations with prior and current owners of these homes (and their
contractors), there have been structural problems in the past, associated with relatively modest
building works, not involving basement excavations.
The proposed double basement at 7 Durham Place would be excavated to a depth of 8-9 metres
through the water table. This would pose major risks of structural instability to the Durham Place
terrace (1-7 Durham Place) as well as adjoining properties at 8-10 Durham Place and potentially 42,
43 and 44 St. Leonard’s Terrace. It would also increase the risk of flooding to nearby properties, all
of which are located close to an area of very high flood risk. The PA describes at some length how
the house and basement at 7 Durham Place would be protected from incursion by water during
construction and longer term. However, it is silent on the ongoing risk for adjoining properties
related to diverted underground water or increased runoff.
The impact of this proposed development must also be seen in the context of the basement
development that has already been approved at 5-6 Durham Place (PP/15/04516). If the 7 Durham
Place basement PA were approved, there would be basements of 8-9 metres deep being excavated
through the water table under three contiguous properties (5, 6, and 7 Durham Place). Given the
fragile condition of this historic terrace, this must surely pose an untenable risk to a precious,
irreplaceable Chelsea terrace.
In fact, the Structural Construction Method Statement filed with the PA for the approved basement
at 5-6 Durham Place (PP/15/04516) states that while the basement at that house might be
constructed without structural damage, if future additional basements were to be constructed along
the full length of the terrace, there would be major issues related to soil and structural stability, as
well as water flows.
The Basement Impact Study for the 7 Durham Place PA also identifies many risks associated with
excavating the basement at 7 Durham Place to its 8-9 metre proposed depth and the need to dig
below the water table. For example, the following quote is from Section 6.1 of the Study:
“The maximum proposed dig level for the basement excavation (understood to be at 40.80mSD)
below the minimum indicated groundwater level at 44.06mSD in BH1 and therefore groundwater
could be affected by the development. Excavation below the water table in Kempton Park Gravel is
likely to be very problematic.”
Section 6.2 of the Study recommends the ongoing monitoring of likely changes in the ground water
levels, since such variations would present significant challenges and risks to the structural stability
of 7 Durham Place and nearby properties. In light of these significant risks, a 6 month study of
ground water level variations should be required and completed by experts prior to the
consideration of the PA by RBKC.
Finally, we are very concerned about the cumulative effects of the proposed basement
developments at 5-6 and 7 Durham Place. How would they be coordinated to minimize risks and
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nuisance for the neighbours? There should be a Structural Engineering Report that analyses the
combined effect on this historic terrace of excavating three basements under adjacent buildings (5,
6, and 7 Durham Place).
This 7 Durham Place PA provides insufficient information on these matters and it assumes that the 7
Durham Place basement would be completed prior to the basement at 5-6 Durham Place. Is this
realistic? Perhaps the owners of 5-6 and 7 Durham Place should be required by RBKC to file a joint
Planning Application for the proposed basements under their properties so that the RBKC can
evaluate the entire development scheme as a whole. There are major concerns related to traffic,
noise, nuisance, dust, etc. for each basement development that are compounded by the potential of
basements being constructed under 5,6,and 7 Durham Place.
In the absence of proof that this proposed 7 Durham Place basement development would not cause
structural or flooding risk to neighbouring properties or the terrace as a whole, this PA should be
refused.
THE PROPOSED DEVELOPMENT WOULD DENIGRATE THE BEAUTY AND CHARACTER OF THE
CONSERVATION AREA AND CAUSE UNACCEPTABLE NOISE, NUISANCE AND POTENTIAL HEALTH
RISKS DURING CONSTRUCTION AND ON AN ONGOING BASIS
As noted above, the proposed development would involve the intentional felling of protected trees
and potential damage and/or death to the remaining trees. It would also reduce the green space at
the rear of the property. This would result in decreased privacy and residential amenity and
increased overlooking for many neighbours on Durham Place, St. Leonard’s Terrace and Tedworth
Square.
The PA also anticipates that there would be two new sky lights at the rear of the property associated
with the basement development. This would cause increased ongoing artificial light pollution,
especially when coupled with the new and more protruding artificial light sources associated with
the owner’s proposed new rear extension expansion and roof modifications (PP/15/07551).
The 7 Durham Place basement PA requests permission to build a more extensive vault at the front of
the building. If this would result in a deepening of the existing front light well, it would be contrary
to Planning Policy which prohibits the building of deeper front light wells in areas where other
equally deep light wells do not exist.
The Planning Documents discuss the need for controlling the adverse impacts of noise and nuisance
upon the neighbours during the building works and on an ongoing basis. However, there is
insufficient information regarding how this would be achieved. We have experienced property
damage and health issues from nearby development projects in the last several years. If any
development plans were approved at 7 Durham Place in the future, the entire building works
(scaffolding, etc.) should be encased in non-permeable plastic to eliminate airborne dust and flying
debris. The owner should be required to reach agreement with the neighbours to assure a safe and
healthy environment were maintained to protect the neighbours and their properties.
The proposed elevations show that the fumes from the swimming pool in the second basement
would be expelled to the rear garden via grilles in the garden step risers. This would be an ongoing
nuisance and would cause potential health risks to affected neighbours and should be prohibited.
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CONCLUSION
For all of the reasons discussed above, we request that the above referenced PA be refused.
Thank you for your consideration of our comments and concerns.
Sincerely,
John A. Boynton
Judith G. Boynton
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