Proposal for Northern Extension of Northolt Tunnel sift report

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INTERNAL INFORMATION 

Northern Extension of Northolt Tunnel SIFT Report  

 

 

Northern Extension of Northolt Tunnel SIFT Report  

C222-ATK-DS-REP-020-000034  

Revision – P06 

 

                         

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INTERNAL INFORMATION 

 

Location: 

Colne Valley 

OPTIONS CONSIDERED: 

Option A  

The Proposed  Scheme as submitted in the hybrid Bill 

(Northolt Tunnel to West Ruislip/ Viaduct across the Colne 

Valley/ Chiltern tunnel east of M25 between jnc 16 and 

17) 

Option B  

Above ground section between Northolt and Chiltern tunnels 

placed underground in bored tunnels with provision for 

connection spurs to Heathrow 

Option C 

As per option B but with no passive provision for a connection 

to Heathrow

 

OPTION DESCRIPTION 

 

 

 

Key Sustainability 

Issue 

Topic 

STAGE: 

Constructio

n or 

Operation 

EDA 

Considered 

(incl. Topic 

and Ref no.) 

Comment 

QUALITATIVE IMPACT DESCRIPTION 

and/or QUANTITIVE ASSESSMENT 

RATI

NG

 

QUALITATIVE IMPACT DESCRIPTION 

and/or QUANTITIVE ASSESSMENT 

RATI

NG

 

QUALITATIVE IMPACT DESCRIPTION 

and/or QUANTITIVE ASSESSMENT 

RATI

NG

 

diversions for CSP/44 and Shire Lane bridleway 

(CSP/43/2). 

990,200 2-way lorry trips. A detailed assessment would 

need to be undertaken in order to understand the 

implications these additional vehicle movements would 

have on the highway network. 

 

Op 

No impacts. 

o 

No impacts. 

o 

No impacts. 

o 

Health & 

wellbeing 

Const 

 

Not assessed at this stage 

N/A 

Not assessed at this stage 

N/A 

Not assessed at this stage 

N/A 

Op 

Not assessed at this stage 

N/A 

Not assessed at this stage 

N/A 

Not assessed at this stage 

N/A 

Socio-

economic 

factors 

Const 

 

In-combination noise and visual impacts on the De 

Vere Hotel.

 

These in-combination impacts will occur 

over a period of 15 months and are likely to have a 

significant amenity effect on this business. 

o 

The Denham Grove (De Vere Hotel) is likely to be 

impacted by noise and loss of visual amenity as a 

consequence of the construction of shaft E1 and possibly 

to a lesser extent the ‘gap’ structure. It is likely that the 

impacts would not be as great as those experienced under 

Option A. 

+ 

As Option B. 

+ 

Op 

Operational noise and visual amenity impacts on the 

De Vere Hotel.

 

Given these in combination effects 

and the high level of sensitivity, the Proposed 

Scheme is assessed to have a significant amenity 

effect on this business. 

o 

No impacts. 

+ 

As Option B. 

+ 

Sustainable 

consumption and 

production 

Agriculture, 

soil & land 

use 

Const 

 

The construction phase will result in the temporary 

disturbance of approximately 144.1ha of land of Best 

and Most Versatile (BMV) quality and of that 84.4ha 

would be lost permanently. Permanent BMV land 

loss is a consequence of areas of permanent 

infrastructure as well as land that will revert to 

landscape and ecological mitigation areas. As BMV 

land in this area is a receptor of medium sensitivity 

the effect is assessed as a moderate adverse effect 

of the Proposed Scheme, which is significant. 

 

Three holdings would be impacted during 

construction (Park Lodge Farm, Home Farm and 

Denham Park Farm) as a consequence of temporary 

land take and severance. The effects have been 

assessed as major adverse for Park Lodge Farm and 

moderate adverse for Home Farm and Denham Park 

Farm. 

o 

With the exception of the 700m gap to the south of the 

Chiltern tunnel southern portal and the National Grid 

Feeder Station to the south of Harvil Road, limited 

agricultural land would be removed permanently for the 

construction of the extended tunnel option and thus the 

permanent impact on agriculture, forestry and soil would 

be reduced if the Northolt extended tunnel options are 

constructed compared to the Proposed Scheme. 

However, the area of agricultural land that would be 

required temporarily during construction of Option B and 

C is assumed to be the virtually the same as the Proposed 

Scheme with the same areas of land required for 

sustainable placement in CFA6 and CFA7 and the same 

areas of land required for construction, logistics 

management, chalk dewatering and soil storage on the 

agricultural land below the Chiltern tunnel southern 

portal and thus the construction impacts Options B and C 

are assumed to be the same as the Proposed Scheme. 

However, there may be some benefits as a consequence 

of the avoidance of utility diversions. 

o 

As Option B. 

o 

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