HomeMy WebLinkAbout2560508 - F.I. Received Doc. - Infiltration Rate TestARC DESIGN SERVICES
PLANNING CONSULTANTS -SITE SUITABILITY ASSESSORS
Mountain Pole,Kells,Co.Meath.
Mob:087-9520269
arcdesignservices@gmail.com
Infiltration Rate Tests at
Tyrone Guthrie Centre,Annaghmakerrig House,Newbliss,Co.Monaghan,H18 PP70
Please find details of a soakaway tests carried out in accordance with BRE Digest 365 on
14/04/2026
1no.test hole was dug on the proposed site in the approximate area where the soakaway will
be located.
The dimensions of the hole =1.31M X 1.45M X 1.0M deep.The hole was filled with water to a
depth of 0.35m below ground level and the time was recorded when water level reached 75%
effective depth and also at 25%effective depth.
This procedure was carried out as per BRE Digest 365 and the results recorded and
the infiltration rate was calculated using the formula below.
Soil infiltration rate,f =Vp75 –25 =0.6173 =0.00000502 m/sec
ap50 X tp75 –25 1.794 x 68,520
Total Impermeable Roof Area =292.45 m2
All this information was entered into the spreadsheet attached and the size of the
soakaways were calculated at
Soakaway =11.0M wide,7.0M long and 0.7M below invert level of inflow pipe,30%
free volume.Half Empty Time of 22.53 hours
Minimum separating distances of 5m from the proposed dwelling and 3m from the
boundaries must be achieved.All driveways to be permeable paving/gravel.
Where possible,SUDS solutions should be used to lessen the hydraulic loading to
the soakaway.Samples of various methods are shown at the end of the report.RECEIVED: 19/06/2026
Design in accordance with BRE Digest 365
TABLE 1
Values of Factor Z1 for rainfall duration D and ratio r
Duration Z1
(mm)
10 0.5 I =then Inflow from the impermeable area drained to the Soakaway
15 0.61 O =the Outflow infiltrating into the soil during rainfall
30 0.78 S =the required Storage in Soakaway to Balance temporarily
Inflow &Outflow
R =the Total rainfall in a Design Storm
60 1 A =the Impermeable area drained to the soakaway
120 1.23 f =the soil infiltration rate determined in a trial pit at the sit of
the soakaway
240 1.53 D -the Storm Duration
360 1.73 a50 =the internal surface area of the soakaway to 50%effective depth
600 2.04 (this excludes the base area which is assumed to clog with fine
particles and become ineffective in the long term)
TABLE 2
30 year rainfall with
20%Climate
Change increase
Duration M100-D
min
(mm)
10 15.96
15 18.996
30 24.876
60 30.084
120 37.476
240 46.08
360 54.564
720 66.996
Impermeable Area 292.45 (m2)Soil infiltration 0.00000791 (m/sec)
soil type =
gravelly clay
(m/sec)(m3/sec)
(R)Inflow (I)
10 min Rainfall 0.01596 4.67
15 min Rainfall 0.018996 5.56
30 min Rainfall 0.024876 7.27 (I)Inflow =(Impermeable Area)x (Total Rainfall in Design Storm)
60 min Rainfall 0.030084 8.80 (O)Outflow =(a50)x(Soil Infiltration)x (Storm Duration)
120 min Rainfall 0.037476 10.96
240 min Rainfall 0.04608 13.48
360 min Rainfall 0.054564 15.96
600 min Rainfall 0.066996 19.59 RECEIVED: 19/06/2026
Length 11.0 (L)(m)=depth of Soakaway
Breath 7.0 (B)(m)=breath of Soakaway
Effective Depth 0.7 (D)(m)=depth of Soakaway below invert level of inflow pipe
A50 12.6 (as50)(m2)=(Length)*(Breadth)*(2)*(0.5)*(Effective Depth)
Effective area 16.17 (Aeff)(m3)=(Length)*(Breadth)*(Effective Depth)*(Void Ratio)
Void Ratio for Stone Filling 0.30
min m3/sec m3/sec m3 m3
Duration
(D)
Inflow
(I)
Outflow
(O)
Storage Capacity
(S)
Excess
Storage
10 4.67 5.98E-02 16.17 11.56230 0.17 hour /10Min
15 5.56 8.97E-02 16.17 10.70432 0.25 hour /15 min
30 7.27 1.79E-01 16.17 9.07441 0.5 hour /30 min
60 8.80 3.59E-01 16.17 7.73073 1 hour
120 10.96 7.18E-01 16.17 5.92774 2 hour
240 13.48 1.44E+00 16.17 4.12909 4 hour
360 15.96 2.15E+00 16.17 2.36554 6 hour
600 19.59 3.59E+00 16.17 0.16500 10 hourRECEIVED: 19/06/2026
Location of Test Hole Test Hole Before Filling
Test Hole Filled 0.35 below G.L.Test Hole after a period of drainageRECEIVED: 19/06/2026
Location of Test Hole shown by Red Arrow RECEIVED: 19/06/2026
?118.03 m
117.68 m
116.68 m
Existing Paving
115.85 m
115.18 m14439 m²
UA Kitchen 12 m²
Entrance
5 m²
UA WC6 m²
UA WC & Shower
4 m²
Storage
1 m²
El Board
73 m²
Recording Studio
101 m²
Dance Studio
34 m²
Universal Accessible
Studio 1
1 m²
ST
Proposed flower bed
116.50 m
4483925 1700 177
130010001366
1646
7647
Proposed
Paved Area
Proposed
Paved Area
1578
510551965201692221406 m²
Entrance/Lobby
8 m²
Corridor
18173590
20552560
800mm
Door Min
Clear Width
180037006000
Accessible Ramp
Gradient 1:15
Compliant with Part M
8000Accessible Ramp
Gradient 1:15
Compliant with Part M
Covered by Pergola structure
150015001600Grass area369915003698150050001800115.85 m
116.68 m
118.03 m
118.03 m
118.03 m
12002191200
1500
2305 1200 1800 7000Proposed Paved Area
(Level to Match Existing Paving)
1510
1800
2378•
•
Stepped Access Route to Comply with Part M:
Tactile hazard warning surfaces should
be incorporated at both the top and
bottom landings (in accordance with
Diagrams 4a and 4b)
All step nosings should incorporate a
permanently contrasting continuous
material on the tread
889711127306132983373
110007000
101806810
Proposed Soakaway RECEIVED: 19/06/2026
RECEIVED: 19/06/2026
RECEIVED: 19/06/2026
Raised Planter Example
Raised Planter Construction RECEIVED: 19/06/2026
Permeable Paving Cross Section
Permeable Paving Specification RECEIVED: 19/06/2026
Water Butt Example RECEIVED: 19/06/2026