**Document:** ADD Planning Statement Re Drainage Dated
**Application:** 22/01189/B — Proposed erection of two detached townhouses with associated landscaping and parking
**Decision:** Permitted
**Decision Date:** 2024-12-30
**Parish:** Braddan
**Document Type:** report / planning_statement
**Source:** https://planningportal.im/a/55304-braddan-no4-tennis-road-erection-two/documents/1099925
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# ADD Planning Statement Re Drainage Dated
Proposed bungalows adjacent to No.4 Tennis Road, Douglas, Isle of Man Planning Statement Relating to Site Drainage December 2022
## 1. Executive Summary
- 1.1. The proposed surface water drainage system is outlined to have final discharge in to an existing public combined sewer.
- 1.2. The proposed surface water flows are proposed to be attenuated at an equivalent greenfield runoff rate of 7l/s/ha. This has been agreed with the Manx Utilities Authority.
- 1.3. The attenuation design accounts for the impermeable roof, paths and driveway areas.
- 1.4. Attenuation is to be incorporated independently on each plot utilising an underground storage tank.
- 1.5. The proposed foul drainage system is outlined to have final discharge in to an existing public combined sewer
## 2. Introduction
- 2.1. This statement has been prepared by BB Consulting Engineers in support of Planning Applications for the proposed development of 2No Bungalows adjacent to No. 4 Tennis Road, Douglas, Isle of Man. This statement covers the foul and surface water drainage.
- 2.2. This statement is to be read in conjunction with all other application documents relating to this application.
## 3. Site Description
- 3.1. The proposed development is outlined within the EnviroArchitecture drawings which relate to this application.
- 3.2. The proposed development area for each bungalow is 323m2.
- 3.3. The proposed impermeable area for each bungalow 230m2.
- 3.4. The proposed attenuation tank discharge rate for each bungalow is 0.2l/s and is derived from an equivalent greenfield run-off rate of 7l/s/ha as agreed with the MUA.
## 4. Foul Drainage
4.1. A foul drainage connection to an existing public sewer is available and this is the proposed mechanism for discharge.
## 5. Surface Water Drainage
- 5.1. A surface water drainage connection to an existing public sewer is available and this is the proposed mechanism for discharge.
- 5.2. The surface water flows exiting the site are to be attenuated.
- 5.3. Attenuation has been calculated at 10m3 for each bungalow and calculations are provided within Appendix A.
## 6. MAINTENANCE OF SURFACE WATER ASSETSAttenuation TankExtract from CIRIA C753 – SUDS Manual
Proposed bungalows adjacent to No.4 Tennis Road, Douglas, Isle of Man
Planning Statement Relating to Site Drainage
APPENDIX A
Attenuation Calculation – single bungalow
A
| |B B C o n s u l n g E n g i n e ers Ltd 1 0 My rtl e Street, D o u g l a s I s l e o f Ma n , IM1 1 E D|F i l e : A e n ua o n .pfd Netw o r k : S t o r m Netw o r k Dav i d B erg i n 0 8 / 1 2 / 2 0 2 2|Page 1 2 2-1 3 1 Te n n i s Ro a d B u nga low s 1 0 m 3 A e n ua o n Ta n k s|
|---|---|---|---|
|N o d e s N a m e Are a
( h a )
T o f E ( m i n s )
C ove r L eve l ( m )
Eas n g ( m )
N o r t h i n g ( m )
D ept h ( m )
S t orage 0 . 0 2 6 5 . 0 0 1 0 0 . 0 0 0 0 . 0 0 0 0 . 0 0 0 2 . 0 0 0 S i m u la o n S e n g s R a infa l l Meth o d o l o g y
FS R Re g i o n M5-6 0 ( m m )
Ra o-R S u m m e r C V
W inte r C V
FS R E n g l a n d a n d Wa l e s 2 0 . 0 0 0 0 . 3 0 0
0 . 7 5 0
0 . 8 4 0
A n a lys i s S p e e d S k i p Ste a d y State
Dra i n Down T i m e ( m i n s ) A d d i o n a l S t orage ( m³/ h a ) C h e c k D i s c h arge Rate ( s ) C h e c k D i s c h arge Vo l u m e
N o r m a l x 2 4 0 2 0 . 0 x x
Sto r m D ura o n s 1 5 3 0 6 0 1 2 0 1 8 0 2 4 0 3 6 0 4 8 0 6 0 0 7 2 0 9 6 0 1 4 4 0
Re t u r n Pe r i o d (ye ars )
C l i mate C h a nge ( C C % )
A d d i o n a l Are a ( A % )
A d d i o n a l F l o w ( Q % ) 3 0
1 0 0
2 0 2 0
0 0
0 0
N o d e Storage O n l i n e Hydro-Brake ® C ontro l F l a p Va lve
Re p l a c e s Downstre a m L i n k Inve rt Leve l ( m ) D e s i g n D epth ( m ) D e s i g n F low ( l/s )
x
✓ 9 7 . 5 0 0 1 . 5 0 0 0 . 2
O b j e c ve
S u m p Ava i l a b l e Pro d u ct N u m b e r
Mi n O utlet D i a mete r ( m ) Mi n N o d e D i a mete r ( m m )
( H E ) Mi n i m i s e upstre a m st orage
✓ CT L-S H E-0 0 1 8-2 0 0 0-1 5 0 0-2 0 0 0
0 . 0 7 5
1 2 0 0
N o d e Storage D ept h/Are a Storage S t r u c t ure
B a s e Inf C oe c i ent ( m / h r ) S i d e Inf C oe c i ent ( m / h r )
0 . 0 0 0 0 0 0 . 0 0 0 0 0
Safety Fa c t o r Poro s ity
2 . 0 0 . 9 5
Inve rt Leve l ( m ) T i m e t o h a l f e mpty ( m i n s )
9 8 . 0 0 0
D ept h ( m )
Are a ( m ² )
Inf Are a ( m ² )
D ept h ( m )
Are a ( m ² )
Inf Are a ( m ² )
D ept h ( m )
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0 . 0 0 0 1 0 . 0 0 . 0 1 . 0 0 0 1 0 . 0 0 . 0 1 . 0 0 1 0 . 0 0 . 0
|N o d e s N a m e Are a
( h a )
T o f E ( m i n s )
C ove r L eve l ( m )
Eas n g ( m )
N o r t h i n g ( m )
D ept h ( m )
S t orage 0 . 0 2 6 5 . 0 0 1 0 0 . 0 0 0 0 . 0 0 0 0 . 0 0 0 2 . 0 0 0 S i m u la o n S e n g s R a infa l l Meth o d o l o g y
FS R Re g i o n M5-6 0 ( m m )
Ra o-R S u m m e r C V
W inte r C V
FS R E n g l a n d a n d Wa l e s 2 0 . 0 0 0 0 . 3 0 0
0 . 7 5 0
0 . 8 4 0
A n a lys i s S p e e d S k i p Ste a d y State
Dra i n Down T i m e ( m i n s ) A d d i o n a l S t orage ( m³/ h a ) C h e c k D i s c h arge Rate ( s ) C h e c k D i s c h arge Vo l u m e
N o r m a l x 2 4 0 2 0 . 0 x x
Sto r m D ura o n s 1 5 3 0 6 0 1 2 0 1 8 0 2 4 0 3 6 0 4 8 0 6 0 0 7 2 0 9 6 0 1 4 4 0
Re t u r n Pe r i o d (ye ars )
C l i mate C h a nge ( C C % )
A d d i o n a l Are a ( A % )
A d d i o n a l F l o w ( Q % ) 3 0
1 0 0
2 0 2 0
0 0
0 0
N o d e Storage O n l i n e Hydro-Brake ® C ontro l F l a p Va lve
Re p l a c e s Downstre a m L i n k Inve rt Leve l ( m ) D e s i g n D epth ( m ) D e s i g n F low ( l/s )
x
✓ 9 7 . 5 0 0 1 . 5 0 0 0 . 2
O b j e c ve
S u m p Ava i l a b l e Pro d u ct N u m b e r
Mi n O utlet D i a mete r ( m ) Mi n N o d e D i a mete r ( m m )
( H E ) Mi n i m i s e upstre a m st orage
✓ CT L-S H E-0 0 1 8-2 0 0 0-1 5 0 0-2 0 0 0
0 . 0 7 5
1 2 0 0
N o d e Storage D ept h/Are a Storage S t r u c t ure
B a s e Inf C oe c i ent ( m / h r ) S i d e Inf C oe c i ent ( m / h r )
0 . 0 0 0 0 0 0 . 0 0 0 0 0
Safety Fa c t o r Poro s ity
2 . 0 0 . 9 5
Inve rt Leve l ( m ) T i m e t o h a l f e mpty ( m i n s )
9 8 . 0 0 0
D ept h ( m )
Are a ( m ² )
Inf Are a ( m ² )
D ept h ( m )
Are a ( m ² )
Inf Are a ( m ² )
D ept h ( m )
Are a ( m ² )
Inf Are a ( m ² )
0 . 0 0 0 1 0 . 0 0 . 0 1 . 0 0 0 1 0 . 0 0 . 0 1 . 0 0 1 0 . 0 0 . 0
|N o d e s N a m e Are a
( h a )
T o f E ( m i n s )
C ove r L eve l ( m )
Eas n g ( m )
N o r t h i n g ( m )
D ept h ( m )
S t orage 0 . 0 2 6 5 . 0 0 1 0 0 . 0 0 0 0 . 0 0 0 0 . 0 0 0 2 . 0 0 0 S i m u la o n S e n g s R a infa l l Meth o d o l o g y
FS R Re g i o n M5-6 0 ( m m )
Ra o-R S u m m e r C V
W inte r C V
FS R E n g l a n d a n d Wa l e s 2 0 . 0 0 0 0 . 3 0 0
0 . 7 5 0
0 . 8 4 0
A n a lys i s S p e e d S k i p Ste a d y State
Dra i n Down T i m e ( m i n s ) A d d i o n a l S t orage ( m³/ h a ) C h e c k D i s c h arge Rate ( s ) C h e c k D i s c h arge Vo l u m e
N o r m a l x 2 4 0 2 0 . 0 x x
Sto r m D ura o n s 1 5 3 0 6 0 1 2 0 1 8 0 2 4 0 3 6 0 4 8 0 6 0 0 7 2 0 9 6 0 1 4 4 0
Re t u r n Pe r i o d (ye ars )
C l i mate C h a nge ( C C % )
A d d i o n a l Are a ( A % )
A d d i o n a l F l o w ( Q % ) 3 0
1 0 0
2 0 2 0
0 0
0 0
N o d e Storage O n l i n e Hydro-Brake ® C ontro l F l a p Va lve
Re p l a c e s Downstre a m L i n k Inve rt Leve l ( m ) D e s i g n D epth ( m ) D e s i g n F low ( l/s )
x
✓ 9 7 . 5 0 0 1 . 5 0 0 0 . 2
O b j e c ve
S u m p Ava i l a b l e Pro d u ct N u m b e r
Mi n O utlet D i a mete r ( m ) Mi n N o d e D i a mete r ( m m )
( H E ) Mi n i m i s e upstre a m st orage
✓ CT L-S H E-0 0 1 8-2 0 0 0-1 5 0 0-2 0 0 0
0 . 0 7 5
1 2 0 0
N o d e Storage D ept h/Are a Storage S t r u c t ure
B a s e Inf C oe c i ent ( m / h r ) S i d e Inf C oe c i ent ( m / h r )
0 . 0 0 0 0 0 0 . 0 0 0 0 0
Safety Fa c t o r Poro s ity
2 . 0 0 . 9 5
Inve rt Leve l ( m ) T i m e t o h a l f e mpty ( m i n s )
9 8 . 0 0 0
D ept h ( m )
Are a ( m ² )
Inf Are a ( m ² )
D ept h ( m )
Are a ( m ² )
Inf Are a ( m ² )
D ept h ( m )
Are a ( m ² )
Inf Are a ( m ² )
0 . 0 0 0 1 0 . 0 0 . 0 1 . 0 0 0 1 0 . 0 0 . 0 1 . 0 0 1 0 . 0 0 . 0
|N o d e s N a m e Are a
( h a )
T o f E ( m i n s )
C ove r L eve l ( m )
Eas n g ( m )
N o r t h i n g ( m )
D ept h ( m )
S t orage 0 . 0 2 6 5 . 0 0 1 0 0 . 0 0 0 0 . 0 0 0 0 . 0 0 0 2 . 0 0 0 S i m u la o n S e n g s R a infa l l Meth o d o l o g y
FS R Re g i o n M5-6 0 ( m m )
Ra o-R S u m m e r C V
W inte r C V
FS R E n g l a n d a n d Wa l e s 2 0 . 0 0 0 0 . 3 0 0
0 . 7 5 0
0 . 8 4 0
A n a lys i s S p e e d S k i p Ste a d y State
Dra i n Down T i m e ( m i n s ) A d d i o n a l S t orage ( m³/ h a ) C h e c k D i s c h arge Rate ( s ) C h e c k D i s c h arge Vo l u m e
N o r m a l x 2 4 0 2 0 . 0 x x
Sto r m D ura o n s 1 5 3 0 6 0 1 2 0 1 8 0 2 4 0 3 6 0 4 8 0 6 0 0 7 2 0 9 6 0 1 4 4 0
Re t u r n Pe r i o d (ye ars )
C l i mate C h a nge ( C C % )
A d d i o n a l Are a ( A % )
A d d i o n a l F l o w ( Q % ) 3 0
1 0 0
2 0 2 0
0 0
0 0
N o d e Storage O n l i n e Hydro-Brake ® C ontro l F l a p Va lve
Re p l a c e s Downstre a m L i n k Inve rt Leve l ( m ) D e s i g n D epth ( m ) D e s i g n F low ( l/s )
x
✓ 9 7 . 5 0 0 1 . 5 0 0 0 . 2
O b j e c ve
S u m p Ava i l a b l e Pro d u ct N u m b e r
Mi n O utlet D i a mete r ( m ) Mi n N o d e D i a mete r ( m m )
( H E ) Mi n i m i s e upstre a m st orage
✓ CT L-S H E-0 0 1 8-2 0 0 0-1 5 0 0-2 0 0 0
0 . 0 7 5
1 2 0 0
N o d e Storage D ept h/Are a Storage S t r u c t ure
B a s e Inf C oe c i ent ( m / h r ) S i d e Inf C oe c i ent ( m / h r )
0 . 0 0 0 0 0 0 . 0 0 0 0 0
Safety Fa c t o r Poro s ity
2 . 0 0 . 9 5
Inve rt Leve l ( m ) T i m e t o h a l f e mpty ( m i n s )
9 8 . 0 0 0
D ept h ( m )
Are a ( m ² )
Inf Are a ( m ² )
D ept h ( m )
Are a ( m ² )
Inf Are a ( m ² )
D ept h ( m )
Are a ( m ² )
Inf Are a ( m ² )
0 . 0 0 0 1 0 . 0 0 . 0 1 . 0 0 0 1 0 . 0 0 . 0 1 . 0 0 1 0 . 0 0 . 0
|
|F low+ v 1 0 . 2 C opy r i ght © 1 9 8 8-2 0 2 2 C a u seway Te c h n o l o g i e s Ltd|F low+ v 1 0 . 2 C opy r i ght © 1 9 8 8-2 0 2 2 C a u seway Te c h n o l o g i e s Ltd|F low+ v 1 0 . 2 C opy r i ght © 1 9 8 8-2 0 2 2 C a u seway Te c h n o l o g i e s Ltd|F low+ v 1 0 . 2 C opy r i ght © 1 9 8 8-2 0 2 2 C a u seway Te c h n o l o g i e s Ltd|
| |B B C o n s u l n g E n g i n e ers Ltd 1 0 My rtl e Street, D o u g l a s I s l e o f Ma n , IM1 1 E D|F i l e : A e n ua o n .pfd Netw o r k : S t o r m Netw o r k Dav i d B erg i n 0 8 / 1 2 / 2 0 2 2|Page 2 2 2-1 3 1 Te n n i s Ro a d B u nga low s 1 0 m 3 A e n ua o n Ta n k s|
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|Re s u l t s fo r 3 0 ye a r + 2 0 % C C C r i ca l Sto r m D ura o n . L owest m a s s b a l a n c e : 8 7 . 3 7 % N o d e Event U S
N o d e
Pe a k ( m i n s )
L eve l ( m )
D ept h ( m )
In o w ( l/s )
N o d e Vo l ( m ³ )
F l o o d ( m ³ )
Stat u s
L i n k Event ( Upstre a m D ept h )
U S N o d e
L i n k O u l o w ( l/s )
D i s c h arge Vo l ( m ³ )
6 0 0 m i n ute winte r S t orage 4 8 0 9 9 . 6 9 2 1 . 6 9 2 1 . 1 9 . 9 4 9 6 0 . 0 0 0 0 O K
6 0 0 m i n ute winte r S t orage Hydro-Brake ® 0 . 2 8 . 8|Re s u l t s fo r 3 0 ye a r + 2 0 % C C C r i ca l Sto r m D ura o n . L owest m a s s b a l a n c e : 8 7 . 3 7 % N o d e Event U S
N o d e
Pe a k ( m i n s )
L eve l ( m )
D ept h ( m )
In o w ( l/s )
N o d e Vo l ( m ³ )
F l o o d ( m ³ )
Stat u s
L i n k Event ( Upstre a m D ept h )
U S N o d e
L i n k O u l o w ( l/s )
D i s c h arge Vo l ( m ³ )
6 0 0 m i n ute winte r S t orage 4 8 0 9 9 . 6 9 2 1 . 6 9 2 1 . 1 9 . 9 4 9 6 0 . 0 0 0 0 O K
6 0 0 m i n ute winte r S t orage Hydro-Brake ® 0 . 2 8 . 8|Re s u l t s fo r 3 0 ye a r + 2 0 % C C C r i ca l Sto r m D ura o n . L owest m a s s b a l a n c e : 8 7 . 3 7 % N o d e Event U S
N o d e
Pe a k ( m i n s )
L eve l ( m )
D ept h ( m )
In o w ( l/s )
N o d e Vo l ( m ³ )
F l o o d ( m ³ )
Stat u s
L i n k Event ( Upstre a m D ept h )
U S N o d e
L i n k O u l o w ( l/s )
D i s c h arge Vo l ( m ³ )
6 0 0 m i n ute winte r S t orage 4 8 0 9 9 . 6 9 2 1 . 6 9 2 1 . 1 9 . 9 4 9 6 0 . 0 0 0 0 O K
6 0 0 m i n ute winte r S t orage Hydro-Brake ® 0 . 2 8 . 8|Re s u l t s fo r 3 0 ye a r + 2 0 % C C C r i ca l Sto r m D ura o n . L owest m a s s b a l a n c e : 8 7 . 3 7 % N o d e Event U S
N o d e
Pe a k ( m i n s )
L eve l ( m )
D ept h ( m )
In o w ( l/s )
N o d e Vo l ( m ³ )
F l o o d ( m ³ )
Stat u s
L i n k Event ( Upstre a m D ept h )
U S N o d e
L i n k O u l o w ( l/s )
D i s c h arge Vo l ( m ³ )
6 0 0 m i n ute winte r S t orage 4 8 0 9 9 . 6 9 2 1 . 6 9 2 1 . 1 9 . 9 4 9 6 0 . 0 0 0 0 O K
6 0 0 m i n ute winte r S t orage Hydro-Brake ® 0 . 2 8 . 8|
|F low+ v 1 0 . 2 C opy r i ght © 1 9 8 8-2 0 2 2 C a u seway Te c h n o l o g i e s Ltd|F low+ v 1 0 . 2 C opy r i ght © 1 9 8 8-2 0 2 2 C a u seway Te c h n o l o g i e s Ltd|F low+ v 1 0 . 2 C opy r i ght © 1 9 8 8-2 0 2 2 C a u seway Te c h n o l o g i e s Ltd|F low+ v 1 0 . 2 C opy r i ght © 1 9 8 8-2 0 2 2 C a u seway Te c h n o l o g i e s Ltd|
| |B B C o n s u l n g E n g i n e ers Ltd 1 0 My rtl e Street, D o u g l a s I s l e o f Ma n , IM1 1 E D|F i l e : A e n ua o n .pfd Netw o r k : S t o r m Netw o r k Dav i d B erg i n 0 8 / 1 2 / 2 0 2 2|Page 3 2 2-1 3 1 Te n n i s Ro a d B u nga low s 1 0 m 3 A e n ua o n Ta n k s|
|---|---|---|---|
|Re s u l t s fo r 1 0 0 ye a r + 2 0 % C C C r i ca l Sto r m D ura o n . L owest m a s s b a l a n c e : 8 7 . 3 7 % N o d e Event U S
N o d e
Pe a k ( m i n s )
L eve l ( m )
D ept h ( m )
In o w ( l/s )
N o d e Vo l ( m ³ )
F l o o d ( m ³ )
Stat u s
L i n k Event ( Upstre a m D ept h )
U S N o d e
L i n k O u l o w ( l/s )
D i s c h arge Vo l ( m ³ )
7 2 0 m i n ute winte r S t orage 4 2 0 1 0 0 . 0 0 0 2 . 0 0 0 1 . 3 1 0 . 0 2 9 6 3 . 7 2 6 9 FLO O D
7 2 0 m i n ute winte r S t orage Hydro-Brake ® 0 . 3 1 0 . 7|Re s u l t s fo r 1 0 0 ye a r + 2 0 % C C C r i ca l Sto r m D ura o n . L owest m a s s b a l a n c e : 8 7 . 3 7 % N o d e Event U S
N o d e
Pe a k ( m i n s )
L eve l ( m )
D ept h ( m )
In o w ( l/s )
N o d e Vo l ( m ³ )
F l o o d ( m ³ )
Stat u s
L i n k Event ( Upstre a m D ept h )
U S N o d e
L i n k O u l o w ( l/s )
D i s c h arge Vo l ( m ³ )
7 2 0 m i n ute winte r S t orage 4 2 0 1 0 0 . 0 0 0 2 . 0 0 0 1 . 3 1 0 . 0 2 9 6 3 . 7 2 6 9 FLO O D
7 2 0 m i n ute winte r S t orage Hydro-Brake ® 0 . 3 1 0 . 7|Re s u l t s fo r 1 0 0 ye a r + 2 0 % C C C r i ca l Sto r m D ura o n . L owest m a s s b a l a n c e : 8 7 . 3 7 % N o d e Event U S
N o d e
Pe a k ( m i n s )
L eve l ( m )
D ept h ( m )
In o w ( l/s )
N o d e Vo l ( m ³ )
F l o o d ( m ³ )
Stat u s
L i n k Event ( Upstre a m D ept h )
U S N o d e
L i n k O u l o w ( l/s )
D i s c h arge Vo l ( m ³ )
7 2 0 m i n ute winte r S t orage 4 2 0 1 0 0 . 0 0 0 2 . 0 0 0 1 . 3 1 0 . 0 2 9 6 3 . 7 2 6 9 FLO O D
7 2 0 m i n ute winte r S t orage Hydro-Brake ® 0 . 3 1 0 . 7|Re s u l t s fo r 1 0 0 ye a r + 2 0 % C C C r i ca l Sto r m D ura o n . L owest m a s s b a l a n c e : 8 7 . 3 7 % N o d e Event U S
N o d e
Pe a k ( m i n s )
L eve l ( m )
D ept h ( m )
In o w ( l/s )
N o d e Vo l ( m ³ )
F l o o d ( m ³ )
Stat u s
L i n k Event ( Upstre a m D ept h )
U S N o d e
L i n k O u l o w ( l/s )
D i s c h arge Vo l ( m ³ )
7 2 0 m i n ute winte r S t orage 4 2 0 1 0 0 . 0 0 0 2 . 0 0 0 1 . 3 1 0 . 0 2 9 6 3 . 7 2 6 9 FLO O D
7 2 0 m i n ute winte r S t orage Hydro-Brake ® 0 . 3 1 0 . 7|
|F low+ v 1 0 . 2 C opy r i ght © 1 9 8 8-2 0 2 2 C a u seway Te c h n o l o g i e s Ltd|F low+ v 1 0 . 2 C opy r i ght © 1 9 8 8-2 0 2 2 C a u seway Te c h n o l o g i e s Ltd|F low+ v 1 0 . 2 C opy r i ght © 1 9 8 8-2 0 2 2 C a u seway Te c h n o l o g i e s Ltd|F low+ v 1 0 . 2 C opy r i ght © 1 9 8 8-2 0 2 2 C a u seway Te c h n o l o g i e s Ltd|
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